Thursday, June 3, 2010
Hidroponics
Hydroponics (From the Greek words hydro, water and ponos, labor) is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk.
Researchers discovered in the 19th century that plants absorb essential mineral nutrients as inorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant's water supply artificially, soil is no longer required for the plant to thrive. Almost any terrestrial plant will grow with hydroponics. Hydroponics is also a standard technique in biology research and teaching.
History
The study of crop nutrition began thousands of years ago. Ancient history tells us that various experiments were undertaken by Theophrastus (372-287 B.C.), while several, extant botanical writings of Dioscorides date from the first century AD.[1]
The earliest published work on growing terrestrial plants without soil was the 1627 book, Sylva Sylvarum by Sir Francis Bacon, printed a year after his death. Water culture became a popular research technique after that. In 1699, John Woodward published his water culture experiments with spearmint. He found that plants in less pure water sources grew better than plants in distilled water. By 1842 a list of nine elements believed to be essential to plant growth had been made out, and the discoveries of the German botanists, Julius von Sachs and Wilhelm Knop, in the years 1859-65, resulted in a development of the technique of soilless cultivation.[1] Growth of terrestrial plants without soil in mineral nutrient solutions was called solution culture. It quickly became a standard research and teaching technique and is still widely used today. Solution culture is now considered a type of hydroponics where there is no inert medium.
In 1929, Professor William Frederick Gericke of the University of California at Berkeley began publicly promoting that solution culture be used for agricultural crop production.[2] He first termed it aquaculture but later found that aquaculture was already applied to culture of aquatic organisms. Gericke created a sensation by growing tomato vines twenty-five feet high in his back yard in mineral nutrient solutions rather than soil.[3] By analogy with the ancient Greek term for agriculture, geoponics, the science of cultivating the earth, Gericke introduced the term hydroponics in 1937 (although he asserts that the term was suggested by Dr. W. A. Setchell, of the University of California) for the culture of plants in water (from the Greek hydros, "water", and ponos, "labor").[1]
Reports of Gericke's work and his claims that hydroponics would revolutionize plant agriculture prompted a huge number of requests for further information. Gericke refused to reveal his secrets claiming he had done the work at home on his own time. This refusal eventually resulted in his leaving the University of California. In 1940, he wrote the book, Complete Guide to Soilless Gardening.
Two other plant nutritionists at the University of California were asked to research Gericke's claims. Dennis R. Hoagland and Daniel I. Arnon wrote a classic 1938 agricultural bulletin, The Water Culture Method for Growing Plants Without Soil,[4] debunking the exaggerated claims made about hydroponics. Hoagland and Arnon found that hydroponic crop yields were no better than crop yields with good quality soils. Crop yields were ultimately limited by factors other than mineral nutrients, especially light. This research, however, overlooked the fact that hydroponics has other advantages including the fact that the roots of the plant have constant access to oxygen and that the plants have access to as much or as little water as they need. This is important as one of the most common errors when growing is over- and under- watering; and hydroponics prevents this from occurring as large amounts of water can be made available to the plant and any water not used, drained away, recirculated, or actively aerated, eliminating anoxic conditions which drown root systems in soil. In soil, a grower needs to be very experienced to know exactly how much water to feed the plant. Too much and the plant will not be able to access oxygen; too little and the plant will lose the ability to transport nutrients, which are typically moved into the roots while in solution.
These two researchers developed several formulas for mineral nutrient solutions, known as Hoagland solution. Modified Hoagland solutions are still used today.
One of the early successes of hydroponics occurred on Wake Island, a rocky atoll in the Pacific Ocean used as a refueling stop for Pan American Airlines. Hydroponics was used there in the 1930s to grow vegetables for the passengers. Hydroponics was a necessity on Wake Island because there was no soil, and it was prohibitively expensive to airlift in fresh vegetables.
In the 1960s, Allen Cooper of England developed the Nutrient film technique. The Land Pavilion at Walt Disney World's EPCOT Center opened in 1982 and prominently features a variety of hydroponic techniques. In recent decades, NASA has done extensive hydroponic research for their Controlled Ecological Life Support System or CELSS. Hydroponics intended to take place on Mars are using LED lighting to grow in different color spectrum with much less heat.
In 1978, hydroponics pioneer Dr. Howard Resh published the first edition of his book "Hydroponics Food Production." This book (now updated) spurred what has become known as the 3-part base nutrients formula that is still a major component of today's hydroponics gardening. Resh later went on to publish other books, and is currently in charge of a highly advanced hydroponics research and production facility in the Caribbean.
Origin
Soilless culture
Gericke originally defined hydroponics as crop growth in mineral nutrient solutions, with no solid medium for the roots. He objected in print to people who applied the term hydroponics to other types of soilless culture such as sand culture and gravel culture. The distinction between hydroponics and soilless culture of plants has often been blurred. Soilless culture is a broader term than hydroponics; it only requires that no soils with clay or silt are used. Note that sand is a type of soil yet sand culture is considered a type of soilless culture. Hydroponics is a subset of soilless culture. Many types of soilless culture do not use the mineral nutrient solutions required for hydroponics.
Billions of container plants are produced annually, including fruit, shade and ornamental trees, shrubs, forest seedlings, vegetable seedlings, bedding plants, herbaceous perennials and vines. Most container plants are produced in soilless media, representing soilless culture. However, most are not hydroponics because the soilless medium often provides some of the mineral nutrients via slow release fertilizers, cation exchange and decomposition of the organic medium itself. Most soilless media for container plants also contain organic materials such as peat or composted bark, which provide some nitrogen to the plant. Greenhouse growth of plants in peat bags is often termed hydroponics, but technically it is not because the medium provides some of the mineral nutrients.
Advantages
Some of the reasons why hydroponics is being adapted around the world for food production are the following:
* No soil is needed
* The water stays in the system and can be reused- thus, lower water costs
* It is possible to control the nutrition levels in their entirety- thus, lower nutrition costs
* No nutrition pollution is released into the environment because of the controlled system
* Stable and high yields
* Pests and diseases are easier to get rid of than in soil because of the container's mobility
Today, hydroponics is an established branch of agronomy. Progress has been rapid, and results obtained in various countries have proved it to be thoroughly practical and to have very definite advantages over conventional methods of horticulture. The two chief merits of the soil-less cultivation of plants are, first, much higher crop yields, and second, hydroponics can be used in places where in-ground agriculture or gardening is not possible.
Thus not only is it a profitable undertaking, but one which has proved of great benefit to humanity. People living in crowded city streets, without gardens, can grow fresh vegetables and fruits in window-boxes or on rooftops. By means of hydroponics all such places can be made to yield a regular and abundant supply of fresh greens. Deserts, rocky and stony land in mountainous districts or barren and sterile areas can be made productive at relatively low cost[citation needed].
Other advantages include faster growth combined with relative freedom from soil disease, and consistency in crops, the quality of produce being excellent[citation needed]. There is also a considerable reduction in growing area. Weeds are practically non-existent, while standard methods and automatic operations mean less labor, lower cost, and less difficult manual labor. As some plants can be raised out of season, better control of crops naturally results.
Disadvantages
The hydroponic conditions (presence of fertilizer and high humidity) create an environment that stimulates salmonella growth.[5] Another disadvantage is pathogens attacks including damp-off due to Verticillium wilt caused by the high moisture levels associated with hydroponics and overwatering of soil based plants. Also, many hydroponic plants require different fertilizers and containment systems[6]
Techniques
The two main types of hydroponics are solution culture and medium culture. Solution culture does not use a solid medium for the roots, just the nutrient solution. The three main types of solution culture are static solution culture, continuous flow solution culture and aeroponics. The medium culture method has a solid medium for the roots and is named for the type of medium, e.g. sand culture, gravel culture or rockwool culture. There are two main variations for each medium, subirrigation and top irrigation. For all techniques, most hydroponic reservoirs are now built of plastic but other materials have been used including concrete, glass, metal, vegetable solids and wood. The containers should exclude light to prevent algae growth in the nutrient solution.
Static solution culture
In static solution culture, plants are grown in containers of nutrient solution, such as glass Mason jars (typically in-home applications), plastic buckets, tubs or tanks. The solution is usually gently aerated but may be unaerated. If unaerated, the solution level is kept low enough that enough roots are above the solution so they get adequate oxygen. A hole is cut in the lid of the reservoir for each plant. There can be one to many plants per reservoir. Reservoir size can be increased as plant size increases. A homemade system can be constructed from plastic food containers or glass canning jars with aeration provided by an aquarium pump, aquarium airline tubing and aquarium valves. Clear containers are covered with aluminium foil, butcher paper, black plastic or other material to exclude light, thus helping to eliminate the formation of algae. The nutrient solution is either changed on a schedule, such as once per week, or when the concentration drops below a certain level as determined with an electrical conductivity meter. Whenever the solution is depleted below a certain level, either water or fresh nutrient solution is added, A Mariotte's bottle, or a float valve, can be used to automatically maintain the solution level. In raft solution culture, plants are placed in a sheet of buoyant plastic that is floated on the surface of the nutrient solution. That way, the solution level never drops below the roots.
Continuous flow solution culture
In continuous flow solution culture the nutrient solution constantly flows past the roots. It is much easier to automate than the static solution culture because sampling and adjustments to the temperature and nutrient concentrations can be made in a large storage tank that serves potentially thousands of plants. A popular variation is the nutrient film technique or NFT whereby a very shallow stream of water containing all the dissolved nutrients required for plant growth is recirculated past the bare roots of plants in a watertight gully, also known as channels. Ideally, the depth of the recirculating stream should be very shallow, little more than a film of water, hence the name 'nutrient film'. This ensures that the thick root mat, which develops in the bottom of the channel, has an upper surface which, although moist, is in the air. Subsequently, there is an abundant supply of oxygen to the roots of the plants. A properly designed NFT system is based on using the right channel slope, the right flow rate and the right channel length. The main advantage of the NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen and nutrients. In all other forms of production there is a conflict between the supply of these requirements, since excessive or deficient amounts of one results in an imbalance of one or both of the others. NFT, because of its design, provides a system where all three requirements for healthy plant growth can be met at the same time, providing the simple concept of NFT is always remembered and practised. The result of these advantages is that higher yields of high quality produce are obtained over an extended period of cropping. A downside of NFT is that it has very little buffering against interruptions in the flow e.g. power outages, but overall, it is probably one of the more productive techniques.
The same design characteristics apply to all conventional NFT systems. While slopes along channels of 1:100 have been recommended, in practice it is difficult to build a base for channels that is sufficiently true to enable nutrient films to flow without ponding in locally depressed areas. Consequently, it is recommended that slopes of 1:30 to 1:40 are used. This allows for minor irregularities in the surface but, even with these slopes, ponding and waterlogging may occur. The slope may be provided by the floor, or benches or racks may hold the channels and provide the required slope. Both methods are used and depend on local requirements, often determined by the site and crop requirements.
As a general guide, flow rates for each gully should be 1 liter per minute. At planting, rates may be half this and the upper limit of 2L/min appears about the maximum. Flow rates beyond these extremes are often associated with nutritional problems. Depressed growth rates of many crops have been observed when channels exceed 12 metres in length. On rapidly growing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen may be depleted over the length of the gully. Consequently, channel length should not exceed 10–15 metres. In situations where this is not possible, the reductions in growth can be eliminated by placing another nutrient feed half way along the gully and reducing flow rates to 1L/min through each outlet.
Aeroponics
Main article: Aeroponics
Aeroponics is a system where roots are continuously or discontinuously kept in an environment saturated with fine drops (a mist or aerosol) of nutrient solution. The method requires no substrate and entails growing plants with their roots suspended in a deep air or growth chamber with the roots periodically wetted with a fine mist of atomized nutrients. Excellent aeration is the main advantage of aeroponics.
Aeroponic techniques have proved to be commercially successful for propagation, seed germination, seed potato production, tomato production, leaf crops and micro-greens.[7] Since inventor Richard Stoner commercialized aeroponic technology in 1983, aeroponics has been implemented as an alternative to water intensive hydroponic systems worldwide.[8] The limitation of hydroponics is the fact that 1 kg of water can only hold 8 mg of air, no matter if aerators are utilized or not.
Another distinct advantage of aeroponics over hydroponics is that any species of plants can be grown in a true aeroponic system because the micro environment of an aeroponic can be finely controlled. The limitation of hydroponics is that only certain species of plants can survive for so long in water before they become water logged. The advantage of aeroponics is due to the fact that suspended aeroponic plants receive 100% of the available oxygen and CO2 to the roots zone, stems and leaves,[9] thus accelerating biomass growth and reducing rooting times. NASA research has shown that aeroponically grown plants have an 80% increase in dry weight biomass (essential minerals) compared to hydroponically grown plants. Aeroponics used 65% less water than hydroponics. NASA also concluded that aeroponically grown plants requires ¼ the nutrient input compared to hydroponics. Unlike hydroponically grown plants, aeroponically plants will not suffer transplant shock when transplanted to soil. Unlike hydroponics, aeroponics also offers growers the ability to reduce the spread of disease and pathogens.[10] Aeroponics is also widely used in laboratory studies of plant physiology and plant pathology. Aeroponic techniques have been given special attention from NASA since a mist is easier to handle than a liquid in a zero gravity environment.
Passive subirrigation
Main article: Passive hydroponics
Passive subirrigation, also known as passive hydroponics or semi-hydroponics, is a method where plants are grown in an inert porous medium that transports water and fertilizer to the roots by capillary action from a separate reservoir as necessary, reducing labor and providing a constant supply of water to the roots. In the simplest method, the pot sits in a shallow solution of fertilizer and water or on a capillary mat saturated with nutrient solution. The various hydroponic media available, such as expanded clay and coconut husk, contain more air space than more traditional potting mixes, delivering increased oxygen to the roots, which is important in epiphytic plants such as orchids and bromeliads, whose roots are exposed to the air in nature. Additional advantages of passive hydroponics are the reduction of root rot and the additional ambient humidity provided through evaporation.
Ebb and flow / Flood and drain subirrigation
Main article: Ebb and flow
In its simplest form, there is a tray above a reservoir of nutrient solution. The tray is either filled with growing medium (clay granules being the most common) and planted directly, or pots of medium stand in the tray. At regular intervals, a simple timer causes a pump to fill the upper tray with nutrient solution, after which the solution drains back down into the reservoir. This keeps the medium regularly flushed with nutrients and air. Once the upper tray fills past the drain stop it begins recirculating the water until the pump is turned off and the water in the upper tray drains back into the reservoir.
Run to Waste
In a Run to Waste type system, nutrient and water solution is periodically applied to the medium surface. This may be done in its simplest form, by manually applying a nutrient and water solution once or more times per day in a container of inert growing media, such as rockwool, perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automated with a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a delivery frequency that is governed by the key parameters of plant size, plant growing stage, climate, substrate, and substrate conductivity, pH, and water content.
In a commercial setting, watering frequency is multi factorial and governed by pc or plc based controllers.
Commercial hydroponics production of large plants like tomatoes, cucumber and peppers, use one form or another of run to waste hydroponics.
In environmentally responsible uses, the nutrient rich waste is collected and processed through an on site filtration system to be used many times, making the system very productive.
Deep water culture
Main article: Deep water culture
The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient rich, oxygenated water. Traditional methods favor the use of plastic buckets and large containers with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. The solution is super oxygenised from an air pump combined with porous stones. With this method the plants grow much faster because of the high amount of oxygen that the roots receive.
Media
One of the most obvious decisions hydroponic farmers have to make is which medium they should use. Different media are appropriate for different growing techniques.
Diahydro
Sedimentary rock medium that consists of the fossilized remains of diatoms. Diahydro is extremely high in Silica (87-94%), an essential component for the growth of plants and strengthening of cell walls.
[edit] Expanded clay
Hydroton brand expanded clay pebbles.
Baked clay pellets, also known under the trademarks 'Hydroton' or 'Hydrokorrels' or LECA (light expanded clay aggregate), are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution. The clay pellets are inert, pH neutral and do not contain any nutrient value.
The clay is formed into round pellets and fired in rotary kilns at 1,200 °C (2,192 °F). This causes the clay to expand, like popcorn, and become porous. It is light in weight, and does not compact over time. Shape of individual pellet can be irregular or uniform depending on brand and manufacturing process. The manufacturers consider expanded clay to be an ecologically sustainable and re-usable growing medium because of its ability to be cleaned and sterilized, typically by washing in solutions of white vinegar, chlorine bleach or hydrogen peroxide (H2O2), and rinsing completely.
A less popular view is that clay pebbles are best not re-used even when they are cleaned, due to root growth which may enter the medium. Breaking open a clay pebble after a crop has been grown will reveal this growth.
[edit] Rock wool
Rock wool (mineral wool) is probably the most widely used medium in hydroponics. Rock Wool is an inert substrate for both 'free drainage' and recirculating systems. It is made from molten rock spun into cotton candy-like fibers, resulting in a fibrous medium accessible to capillary action that is not degraded by microbiological activity. Higher density also improves the wicking and dispersion of moisture and nutrients, enticing roots into more areas of the medium, and therefore increasing nutrient fueled sites for premium plant production.
Coir
Coco Peat, also known as coir or coco, is the leftover material after the fibres have been removed from the outermost shell (bolster) of the coconut. Coir is a 100% natural grow and flowering medium.
Perlite
Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in potting soil mixes to decrease soil density. Perlite has similar properties and uses to vermiculite but generally holds more air and less water. If not contained, it can float if flood and drain feeding is used. It is a fusion of granite, obsidian, pumice and basalt. This volcanic rock is naturally fused at high temperatures undergoing what is called "Fusionic Metamorphosis".
Vermiculite
Like perlite, vermiculite is another mineral that has been superheated until it has expanded into light pebbles. Vermiculite holds more water than perlite and has a natural "wicking" property that can draw water and nutrients in a passive hydroponic system. If too much water and not enough air surrounds the plants roots, it's possible to gradually lower the medium's water-retention capability by mixing in increasing quantities of perlite.
Sand
Sand is cheap and easily available. However, it is heavy, does not hold water very well, and it must be sterilized between use.
Gravel
The same type that is used in aquariums, though any small gravel can be used, provided it is washed first. Indeed, plants growing in a typical traditional gravel filter bed, with water circulated using electric powerhead pumps, are in effect being grown using gravel hydroponics. Gravel is inexpensive, easy to keep clean, drains well and won't become waterlogged. However, it is also heavy, and if the system doesn't provide continuous water, the plant roots may dry out.
Brick shards
Brick shards have similar properties to gravel. They have the added disadvantages of possibly altering the pH and requiring extra cleaning before reuse.
Polystyrene packing peanuts
Polystyrene packing peanuts are inexpensive, readily available, and have excellent drainage. However, they can be too lightweight for some uses. They are mainly used in closed tube systems. Note that polystyrene peanuts must be used; biodegradable packing peanuts will decompose into a sludge. Plants may absorb styrene and pass it to their consumers; this is a possible health risk.
Wood fiber
Wood fiber, produced from steam friction of wood, is a very efficient organic substrate for hydroponics. It has the advantage that it keeps its structure for a very long time.
Nutrient solutions
Plant nutrients are dissolved in the water used in hydroponics and are mostly in inorganic and ionic form. Primary among the dissolved cations (positively-charged ions) are Ca2+ (calcium), Mg2+ (magnesium), and K+ (potassium); the major nutrient anions in nutrient solutions are NO3-− (nitrate), SO42− (sulfate), and H2PO4− (dihydrogen phosphate).
Numerous 'recipes' for hydroponic solutions are available. Many use different combinations of chemicals to reach similar total final compositions. Commonly-used chemicals for the macronutrients include potassium nitrate, calcium nitrate, potassium phosphate, and magnesium sulfate. Various micronutrients are typically added to hydroponic solutions to supply essential elements; among them are Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), B (boron), Cl (chlorine), and Ni (nickel). Chelating agents are sometimes used to keep Fe soluble. Many variations of the nutrient solutions used by Arnon and Hoagland (see above) have been styled 'modified Hoagland solutions' and are widely used. Variation of different mixes throughout the plant life cycle, further optimizes its nutritional value.[14] Plants will change the composition of the nutrient solutions upon contact by depleting specific nutrients more rapidly than others, removing water from the solution, and altering the pH by excretion of either acidity or alkalinity. Care is required not to allow salt concentrations to become too high, nutrients to become too depleted, or pH to wander far from the desired value.
Commercial
An Aerogarden using hydroponics and aeroponics.
The largest commercial hydroponics facility in the world is Eurofresh Farms in Willcox, Arizona, which sold 125 million pounds of tomatoes in 2005.[15] Eurofresh has 318 acres (1.29 km2) under glass and represents about a third of the commercial hydroponic greenhouse area in the U.S.[16] Eurofresh does not consider its tomatoes organic, but they are pesticide-free. They are grown in rockwool using the run to waste technique.
Some commercial installations use no pesticides or herbicides, preferring integrated pest management techniques. There is often a price premium willingly paid by consumers for produce which is labeled "organic". Some states in the USA require soil as an essential to obtain organic certification. There are also overlapping and somewhat contradictory rules established by the US Federal Government, so some food grown with hydroponics can be certified organic.
Hydroponics also saves water; it uses as little as 1/20 the amount as a regular farm to produce the same amount of food. The water table can be impacted by the water use and run-off of chemicals from farms, but hydroponics may minimize impact as well as having the advantage that water use and water returns are easier to measure. This can save the farmer money by allowing reduced water use and the ability to measure consequences to the land around a farm.
To increase plant growth, lighting systems such as metal halide for growing stage only or high pressure sodium for growing/flowering/blooming stage are used to lengthen the day or to supplement natural sunshine if it is scarce. Metal halide emits more light in the blue spectrum, making it ideal for plant growth but is harmful to unprotected skin and can cause skin cancer. High pressure sodium emits more light in the red spectrum, meaning that it is best suited for supplementing natural sunshine and can be used throughout the growing cycle. However, these lighting systems require large amounts of electricity to operate.
AgriHouse Inc under NASA grants researched and developed a high-efficiency low-wattage lighting array that eliminates insects from eating hydroponically and aeroponically grown crops. AgriHouse's low-wattage light array system has only a 2 °F (1.11 °C) heat transfer from the bulb to the crop, allowing the light source to be extremely close to the growing crop. The NASA lighting system allows Grow-Anywhere LLC, Denver, Colorado, to grow mass volumes of leaf crops and micro-greens using aeroponics in an industrial warehouse space without sunlight. According, Dr. Larry Forrest, owner, this type of operation could not have been achieved with metal halide or high pressure sodium bulbs due to their high energy cost of operation
The environment in a hydroponics greenhouse is tightly controlled for maximum efficiency and this new mindset is called Soil-less/Controlled Environment Agriculture (S/CEA). With this growers can make ultra-premium foods anywhere in the world, regardless of temperature and growing seasons. Growers monitor the temperature, humidity, and pH level constantly.
Hydroponics have been used to enhance vegetables to provide more nutritional value. A hydroponic farmer in Virginia has developed a calcium and potassium enriched head of lettuce, scheduled to be widely available in April 2007. Grocers in test markets have said that the lettuce sells "very well", and the farmers claim that their hydroponic lettuce uses 90% less water than traditional soil farming.
Advancements
With pest problems reduced, and nutrients constantly fed to the roots, productivity in hydroponics is high, although plant growth can be limited by the low levels of carbon dioxide in the atmosphere, or limited light exposure. To increase yield further, some sealed greenhouses inject carbon dioxide into their environment to help growth (CO2 enrichment), add lights to lengthen the day, or control vegetative growth etc.(from wikepedia article)
hydroculture
Hydroculture is a type of hydroponics in which plants are grown in a media that allows the distribution of water and nutrients through capillary action.
Clay aggregate such as LECA and Hydroton can be used to anchor plants when growing with hydroponics.
Advantages include ease of maintenance as watering and feeding involve just topping up the reservoir of growing solution. Soil borne pests don't affect plants grown using hydroculture.
What is Hydroculture?
Hydroculture is a method of growing plants without the use of soil. With the method I use, and detail on this page, plants are grown in an absorbent aggregate and nutrients. Some of the advantages of houseplants grown in hydroculture are the water reservoir makes it easy to see when the plant requires water, the aggregate is open therefore allowing air to circulate around the roots, and the reservoir coupled with using absorbent aggregate helps create humidity around the plant. This method of hydroculture is sometimes referred to as 'passive hydroponics'.
There is another method, which uses nutrient solution, called 'active hydroponics' or often referred to just as hydroponics. This system often uses a form of nutrient delivery system to deliver the nutrients to the roots. I will only be detailing the method of houseplant hydroculture I use on this page, however there are other web sites which detail active hydroponics and also various other methods of hydroculture.
The word "hydro" derives its name from the Greek word "hudor" meaning water, hence hydroculture = water culture.
Wikipedia entry for hydroponics (inc. passive hydroponics).
Aggregates
I use expanded clay pebbles which are specifically sold for hydroculture. I get my expanded clay pebbles from a hydroponics stockist who stocks them in 10 litre and 50 litre bags. These are made of clay which has been fired to a high temperature to create a hard outer shell and a honeycomb-like centre that allows for water absorption. I clean these as described in the cleaning section of this page.
Aggregate performs a similar role to that of soil in that it supports the plants. Expanded clay pebbles have the ability to absorb nutrient solution and transferring it through the aggregate via a capillary action from a reservoir to the plant roots.
A search on the internet for hydroculture, passive hydroponics or hydroponics usually leads to various suppliers sites who stock suitable aggregates, some offer it in various sizes and I usually use the smaller pebbles for fine rooted plants and the larger sizes for all others. You can use the search box below if you like.
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Nutrient Solution
This is the 'food and water' for the plants. Special nutrients are available for hydroculture, these usually come in either powder or liquid form which are added to water to make a solution, or in a resin or tablet form which is added to the aggregate or reservoir. With the resin form the food is slowly released over long periods of time, often months.
Hydroculture nutrients differ from some houseplant foods in that they contain extra trace elements. Some nutrient solutions may not be suitable for indoor houseplant hydroculture, I always check the suitability with the manufacturer first. Instructions on the use of nutrients should be supplied with them.
Nutrients are available in many different NPK (N=Nitrogen, P=Phosphorus, K=Potassium) formulations, these are expressed as percentages. By selecting different NPK formulations the growth, flowering or crop of the plant can be controlled to a certain degree. I use a general purpose nutrient for all my plants but some plants may appreciate a different formulation.
Converting Plants
The easiest method I have found for converting a houseplant to hydroculture is to use one that has been water rooted because the root system seems to be slightly different to one that has been grown in soil. The method I use is to take a soft stemmed cutting and suspending it in a container full of water, this can be done by placing a piece of cardboard on the top of the container and putting the cutting through a hole in the centre. The cutting is put somewhere where it will get light but not direct sunlight and also somewhere that is not too hot. The water in the container is changed every few days to stop it becoming stagnent. When a good root system has developed the cardboard is carefully removed from the plant avoiding damaging the plant, the plant is then transferred to hydroculture as described in the containers section. Then I place the plant into a propagator or place a transparent plastic bag, with air holes, over it to keep the humidity high for up to 1 month and I also use only water, not nutrient solution, for this time.
Hydroculture - Water Rooting
Although water rooting is possibly the most reliable method of getting a houseplant into hydroculture, it is not my preferred method. I'm a little impatient and I like to see quick results, therefore I prefer to convert a soil (compost) rooted houseplant. I always use young houseplants as large or established ones may be more difficult to convert to hydroculture. The method I use is detailed below:
I soak the plant, in its pot, in room temperature tapwater up to the height of the top of the soil for approximately one hour. This helps soften the soil from around the roots.
Remove the plant from the pot, place the plant roots back into a bucket of clean room temperature water and agitate to remove most of the soil.
Remove the plant from the bucket and run room temperaure clean water over the roots until all the soil is removed. It is important to remove ALL the soil.
Cut off any dead roots. Trimming the roots a little seems to help the plant establish better.
The plant is place into a hydroculture pot as described in the containers section.
Water only is added, no nutrients.
I don't add nutrient solution for approximately 4 weeks, only water. The plant will be very sensitive until it has grown a new root system so it will need nurturing for a few weeks, to do this I place the plant into a propagator or place a transparent plastic bag, with air holes, over it to keep the humidity high.
Containers
I currently use the pot and saucer method. This uses pots made of an inert material such as plastic. Plants need converting before they are used in hydroculture.
Pot and Saucer:
This method uses a standard plant pot, with bottom drainage holes, which is placed into a large plant pot saucer. A saucer which is larger than the usual size for the pot is chosen so that it can work as a reservoir, I try to select one that will hold enough nutrient solution for approximately 1 week. The nutrient solution is stored in the saucer. It is possible to get transparent saucers and these make the checking of the nutrient solution level even easier. If several plants are grown in close proximity then, instead of using a seperate saucer for each plant, a large watertight tray can be used to house several pots. A tray without drainage holes is used such as a garden tray or a gravel tray, this is filled with enough nutrient solution to last for approximately 1 week.
Hydroculture - Pot and Saucer
Pot in Pot Method:
This is very similar to the pot and saucer method above except that the plant pot is placed into an watertight pot container instead of a saucer. A plastic pot container which is slightly larger internally than the plant pot, by approximately 1cm all round, is chosen. This allows space which will act as the reservoir. With this method it is more difficult to see the nutrient level, so the pot either needs taking out or a level indicator needs to be used in order to check the nutrient level. Alternatively a transparent plastic pot container can be used but this possibly defeats one of the reason for using a pot container i.e. it does not disguise the plant pot. With this method I try to get a nutrient level height of approximately 1/4 of the inner pot. The level is measured when the system is assembled, i.e. when the fully potted plant pot is placed inside the plant pot container.
Level Indicator:
It's possible to make a level indicator. I've tried several methods over the years and one of the most successful uses plastic tube, such as 20/22mm rigid plastic water pipe or rigid plastic conduit, and a plastic drinking straw. The plastic tube goes in the inner pot and sits on the bottom. There's a small notch in the bottom of the tube to ensure that water can enter and exit it, making sure that the notch isn't large enough to allow aggregate to enter the tube. The straw has the bottom end sealed, if it's not sealed then it will not float. Two marks are drawn on the straw to indicate minimum and maximum nutrient level. To set the marks, I assemble the inner and outer pot without any aggregate and put the plastic tube in place. Put the straw into the tube and draw a line around it level with the top of the tube, this is the minimum level. Now I put water in to approximately 1/4 of the height of the pots and draw another mark around the straw, this is the maximum level.
Hydroculture - Level Indicator
Commercial Kits:
There are commercial hydroculture kits available which use an outer watertight pot and an inner pot which has drainage holes or slots. These kits usually come with a nutrient level indicator which makes it very easy to see exactly when they need topping up. The manufacturers/suppliers of these kits can usually supply nutrients too.
Potting
Houseplants need converting prior to being used in hydroculture, refer to the converting plants section on this page. Potting is done in a similar way to potting in soil except that aggregate is used. Aggregate is place in the bottom of the pot to approximately 1/3 the height of the pot, the plant roots are held suspended in the pot then aggregate is poured around the roots to the same height as the plant was originally potted. I waggle the plant and tap the pot to ensure that the aggregate fully surrounds the roots then run room temperature tap water through it.
When a plant is first transferred to hydroculture the roots sit in the clay pebbles and not the water/nutrient solution, the plants roots will receive moisture from the reservoir through the capillary action of the aggregate. This is why the base of the pot is filled with clay pebbles and the roots are placed on top of them. It is also necessary to ensure that the reservoir is not too deep as this will also cause the roots to sit in the water/nutrient solution. When the plant is established it may grow roots downwards into the reservoir, this seems to be OK with the plants I have grown.
Nutrient Level
A nutrient solution is made following the manufacturers instructions and this is then added to the pot and allowed to drain through into the reservoir, being careful to not overfill the reservoir. I allow the level to fall until no nutrient solution is in contact with the bottom of the pot before adding more. Some plant pots have feet on the bottom of them which stand the base of the pot off of the reservoir by a few millimetres, with these I don't let the reservoir empty, I top it up when the nutrient level falls to the top of the feet. When the reservoir has emptied the aggregate can dry out quickly, especially on hot days. Some plants are not tolerant of dry aggregate so I add nutrient solution as soon as the reservoir empties.
As mentioned there are slow release resin nutrients available, these are usually added to the aggregate or reservoir, depending on the manufacturers instructions, and will release nutrients slowly for several months. If these are used then it is only necessary to add water to the plants. The resin will need re-adding when they are exhausted.
Tapwater is used for making the nutrient solution. I allow this to stand for several hours to reach room temperature.
Suitable Plants
Click here for a list of plants reported to be suitable for hydroculture which was kindly supplied by PurLec Hydroculture. This is not a definitive list and I will add to it when I find other suitable plants or I'm informed of such. If you know of any suitable plants for hydroculture that you would like to tell me about then I can be contacted via the feedback form on my FAQs & Contact page.
I tend to experiment with commonly available plants and see if they will convert to hydroculture. The majority of the plants I have tried convert successfully but I have had a few failures. It's impossible for me to say if the failures are due to the plant not liking hydroculture or whether it's because I tend to experiment with techniques and may get it wrong sometimes.
Light
Nothing special here. Hydroculture plants seem to have the same light requirements as soil grown plants. I follow the recommendations on the plant label or use a houseplant reference book.
Cleaning
Cleanliness of the equipment helps to reduce the risk of plant disease. The hydroculture equipment I use is cleaned, before it is used, using the following methods:
Cleaning Aggregate:
Thoroughly rinse with clean water until the water is clear.
Place aggregate into a bucket.
Fill the bucket with tapwater
Leave to soak for approximately 1hour.
Cleaning Pots:
Place pots into a bucket containing clean water and a small amount of washing-up liquid (hand dishwashing liquid).
Using a small soft clean brush scrub the inside and outside of the pots.
Thoroughly rinse the pots with clean water.
Aftercare
Hydroculture - Flushing
Apart from ensuring that the plant receives nutrient solution, when required, there is very little aftercare involved.
The plants appreciate being washed from time to time, this helps to remove any dust which has settled on the leafs and salt or nutrient build-up in the aggregate, I also wash out the saucer/pot container at the same time. I do this once a month. The pot is removed from the reservoir and placed under a room temperaure running shower or slow running tap. After cleaning is finished excess water is allowed to drain then the pot is placed back into the reservoir and nutrient solution is added.
Plants need repotting into larger pots as they mature. I do this when the roots start to grow through the drainage holes in the pot. Care is taken when removing the plant from the pot to avoid ripping or breaking too many roots.
Extended Watering
If it's necessary to extend the watering period then I use a larger reservoir such as a garden or gravel tray without drainage holes. The pot is removed from the reservoir and placed in the tray, the tray is then filled with water up to the height that nutrient solution is usually added. It's best to not do this too often as the larger reservoir means that the aggregate will stay wet for longer and some plants like to dry out slightly between watering.
Links
Regal Orchids
A supplier of orchid plants and related products, based in Scotland. Regal Orchids stock 'Hydropots' which consist of an outer pot (vase), inner pot (culture pot) and water level indicator. So, if you're keen to try hydroculture but not keen on the homemade methods described above then these kits may be the solution.
PurLec Hydroculture
A very friendly company who supplied me with a list of plants suitable for hydroculture. Their site contains lots of hydroculture products and very useful information.
Water Roots
A very informative and well laid out site with many photos of plants in hydroculture. The author of this site uses glass containers to contain the aggregate and nutrients. This method provides a very attractive alternative to pots while allowing easy checking of water level. Check out "The Hydro Log" page while you're there, I find it a great read.
How to grow house plants in water
A lens site written by a fellow hydroculture enthusiast. This lens explains hydroculture, helps you get started, and provides valuable resources.
Wikipedia
Hydroponics information on Wikipedia [opens a new browser window].
Answers.com
Hydroponics information on Answers.com
The Flowers & Plants Association
Although not a hydroculture site, this site contains a lot of information on houseplants, including facts, care tips, plant trends and decor. There is also a section on the health benefits of plants.
Clay aggregate such as LECA and Hydroton can be used to anchor plants when growing with hydroponics.
Advantages include ease of maintenance as watering and feeding involve just topping up the reservoir of growing solution. Soil borne pests don't affect plants grown using hydroculture.
What is Hydroculture?
Hydroculture is a method of growing plants without the use of soil. With the method I use, and detail on this page, plants are grown in an absorbent aggregate and nutrients. Some of the advantages of houseplants grown in hydroculture are the water reservoir makes it easy to see when the plant requires water, the aggregate is open therefore allowing air to circulate around the roots, and the reservoir coupled with using absorbent aggregate helps create humidity around the plant. This method of hydroculture is sometimes referred to as 'passive hydroponics'.
There is another method, which uses nutrient solution, called 'active hydroponics' or often referred to just as hydroponics. This system often uses a form of nutrient delivery system to deliver the nutrients to the roots. I will only be detailing the method of houseplant hydroculture I use on this page, however there are other web sites which detail active hydroponics and also various other methods of hydroculture.
The word "hydro" derives its name from the Greek word "hudor" meaning water, hence hydroculture = water culture.
Wikipedia entry for hydroponics (inc. passive hydroponics).
Aggregates
I use expanded clay pebbles which are specifically sold for hydroculture. I get my expanded clay pebbles from a hydroponics stockist who stocks them in 10 litre and 50 litre bags. These are made of clay which has been fired to a high temperature to create a hard outer shell and a honeycomb-like centre that allows for water absorption. I clean these as described in the cleaning section of this page.
Aggregate performs a similar role to that of soil in that it supports the plants. Expanded clay pebbles have the ability to absorb nutrient solution and transferring it through the aggregate via a capillary action from a reservoir to the plant roots.
A search on the internet for hydroculture, passive hydroponics or hydroponics usually leads to various suppliers sites who stock suitable aggregates, some offer it in various sizes and I usually use the smaller pebbles for fine rooted plants and the larger sizes for all others. You can use the search box below if you like.
Enter your search terms Submit search form
Nutrient Solution
This is the 'food and water' for the plants. Special nutrients are available for hydroculture, these usually come in either powder or liquid form which are added to water to make a solution, or in a resin or tablet form which is added to the aggregate or reservoir. With the resin form the food is slowly released over long periods of time, often months.
Hydroculture nutrients differ from some houseplant foods in that they contain extra trace elements. Some nutrient solutions may not be suitable for indoor houseplant hydroculture, I always check the suitability with the manufacturer first. Instructions on the use of nutrients should be supplied with them.
Nutrients are available in many different NPK (N=Nitrogen, P=Phosphorus, K=Potassium) formulations, these are expressed as percentages. By selecting different NPK formulations the growth, flowering or crop of the plant can be controlled to a certain degree. I use a general purpose nutrient for all my plants but some plants may appreciate a different formulation.
Converting Plants
The easiest method I have found for converting a houseplant to hydroculture is to use one that has been water rooted because the root system seems to be slightly different to one that has been grown in soil. The method I use is to take a soft stemmed cutting and suspending it in a container full of water, this can be done by placing a piece of cardboard on the top of the container and putting the cutting through a hole in the centre. The cutting is put somewhere where it will get light but not direct sunlight and also somewhere that is not too hot. The water in the container is changed every few days to stop it becoming stagnent. When a good root system has developed the cardboard is carefully removed from the plant avoiding damaging the plant, the plant is then transferred to hydroculture as described in the containers section. Then I place the plant into a propagator or place a transparent plastic bag, with air holes, over it to keep the humidity high for up to 1 month and I also use only water, not nutrient solution, for this time.
Hydroculture - Water Rooting
Although water rooting is possibly the most reliable method of getting a houseplant into hydroculture, it is not my preferred method. I'm a little impatient and I like to see quick results, therefore I prefer to convert a soil (compost) rooted houseplant. I always use young houseplants as large or established ones may be more difficult to convert to hydroculture. The method I use is detailed below:
I soak the plant, in its pot, in room temperature tapwater up to the height of the top of the soil for approximately one hour. This helps soften the soil from around the roots.
Remove the plant from the pot, place the plant roots back into a bucket of clean room temperature water and agitate to remove most of the soil.
Remove the plant from the bucket and run room temperaure clean water over the roots until all the soil is removed. It is important to remove ALL the soil.
Cut off any dead roots. Trimming the roots a little seems to help the plant establish better.
The plant is place into a hydroculture pot as described in the containers section.
Water only is added, no nutrients.
I don't add nutrient solution for approximately 4 weeks, only water. The plant will be very sensitive until it has grown a new root system so it will need nurturing for a few weeks, to do this I place the plant into a propagator or place a transparent plastic bag, with air holes, over it to keep the humidity high.
Containers
I currently use the pot and saucer method. This uses pots made of an inert material such as plastic. Plants need converting before they are used in hydroculture.
Pot and Saucer:
This method uses a standard plant pot, with bottom drainage holes, which is placed into a large plant pot saucer. A saucer which is larger than the usual size for the pot is chosen so that it can work as a reservoir, I try to select one that will hold enough nutrient solution for approximately 1 week. The nutrient solution is stored in the saucer. It is possible to get transparent saucers and these make the checking of the nutrient solution level even easier. If several plants are grown in close proximity then, instead of using a seperate saucer for each plant, a large watertight tray can be used to house several pots. A tray without drainage holes is used such as a garden tray or a gravel tray, this is filled with enough nutrient solution to last for approximately 1 week.
Hydroculture - Pot and Saucer
Pot in Pot Method:
This is very similar to the pot and saucer method above except that the plant pot is placed into an watertight pot container instead of a saucer. A plastic pot container which is slightly larger internally than the plant pot, by approximately 1cm all round, is chosen. This allows space which will act as the reservoir. With this method it is more difficult to see the nutrient level, so the pot either needs taking out or a level indicator needs to be used in order to check the nutrient level. Alternatively a transparent plastic pot container can be used but this possibly defeats one of the reason for using a pot container i.e. it does not disguise the plant pot. With this method I try to get a nutrient level height of approximately 1/4 of the inner pot. The level is measured when the system is assembled, i.e. when the fully potted plant pot is placed inside the plant pot container.
Level Indicator:
It's possible to make a level indicator. I've tried several methods over the years and one of the most successful uses plastic tube, such as 20/22mm rigid plastic water pipe or rigid plastic conduit, and a plastic drinking straw. The plastic tube goes in the inner pot and sits on the bottom. There's a small notch in the bottom of the tube to ensure that water can enter and exit it, making sure that the notch isn't large enough to allow aggregate to enter the tube. The straw has the bottom end sealed, if it's not sealed then it will not float. Two marks are drawn on the straw to indicate minimum and maximum nutrient level. To set the marks, I assemble the inner and outer pot without any aggregate and put the plastic tube in place. Put the straw into the tube and draw a line around it level with the top of the tube, this is the minimum level. Now I put water in to approximately 1/4 of the height of the pots and draw another mark around the straw, this is the maximum level.
Hydroculture - Level Indicator
Commercial Kits:
There are commercial hydroculture kits available which use an outer watertight pot and an inner pot which has drainage holes or slots. These kits usually come with a nutrient level indicator which makes it very easy to see exactly when they need topping up. The manufacturers/suppliers of these kits can usually supply nutrients too.
Potting
Houseplants need converting prior to being used in hydroculture, refer to the converting plants section on this page. Potting is done in a similar way to potting in soil except that aggregate is used. Aggregate is place in the bottom of the pot to approximately 1/3 the height of the pot, the plant roots are held suspended in the pot then aggregate is poured around the roots to the same height as the plant was originally potted. I waggle the plant and tap the pot to ensure that the aggregate fully surrounds the roots then run room temperature tap water through it.
When a plant is first transferred to hydroculture the roots sit in the clay pebbles and not the water/nutrient solution, the plants roots will receive moisture from the reservoir through the capillary action of the aggregate. This is why the base of the pot is filled with clay pebbles and the roots are placed on top of them. It is also necessary to ensure that the reservoir is not too deep as this will also cause the roots to sit in the water/nutrient solution. When the plant is established it may grow roots downwards into the reservoir, this seems to be OK with the plants I have grown.
Nutrient Level
A nutrient solution is made following the manufacturers instructions and this is then added to the pot and allowed to drain through into the reservoir, being careful to not overfill the reservoir. I allow the level to fall until no nutrient solution is in contact with the bottom of the pot before adding more. Some plant pots have feet on the bottom of them which stand the base of the pot off of the reservoir by a few millimetres, with these I don't let the reservoir empty, I top it up when the nutrient level falls to the top of the feet. When the reservoir has emptied the aggregate can dry out quickly, especially on hot days. Some plants are not tolerant of dry aggregate so I add nutrient solution as soon as the reservoir empties.
As mentioned there are slow release resin nutrients available, these are usually added to the aggregate or reservoir, depending on the manufacturers instructions, and will release nutrients slowly for several months. If these are used then it is only necessary to add water to the plants. The resin will need re-adding when they are exhausted.
Tapwater is used for making the nutrient solution. I allow this to stand for several hours to reach room temperature.
Suitable Plants
Click here for a list of plants reported to be suitable for hydroculture which was kindly supplied by PurLec Hydroculture. This is not a definitive list and I will add to it when I find other suitable plants or I'm informed of such. If you know of any suitable plants for hydroculture that you would like to tell me about then I can be contacted via the feedback form on my FAQs & Contact page.
I tend to experiment with commonly available plants and see if they will convert to hydroculture. The majority of the plants I have tried convert successfully but I have had a few failures. It's impossible for me to say if the failures are due to the plant not liking hydroculture or whether it's because I tend to experiment with techniques and may get it wrong sometimes.
Light
Nothing special here. Hydroculture plants seem to have the same light requirements as soil grown plants. I follow the recommendations on the plant label or use a houseplant reference book.
Cleaning
Cleanliness of the equipment helps to reduce the risk of plant disease. The hydroculture equipment I use is cleaned, before it is used, using the following methods:
Cleaning Aggregate:
Thoroughly rinse with clean water until the water is clear.
Place aggregate into a bucket.
Fill the bucket with tapwater
Leave to soak for approximately 1hour.
Cleaning Pots:
Place pots into a bucket containing clean water and a small amount of washing-up liquid (hand dishwashing liquid).
Using a small soft clean brush scrub the inside and outside of the pots.
Thoroughly rinse the pots with clean water.
Aftercare
Hydroculture - Flushing
Apart from ensuring that the plant receives nutrient solution, when required, there is very little aftercare involved.
The plants appreciate being washed from time to time, this helps to remove any dust which has settled on the leafs and salt or nutrient build-up in the aggregate, I also wash out the saucer/pot container at the same time. I do this once a month. The pot is removed from the reservoir and placed under a room temperaure running shower or slow running tap. After cleaning is finished excess water is allowed to drain then the pot is placed back into the reservoir and nutrient solution is added.
Plants need repotting into larger pots as they mature. I do this when the roots start to grow through the drainage holes in the pot. Care is taken when removing the plant from the pot to avoid ripping or breaking too many roots.
Extended Watering
If it's necessary to extend the watering period then I use a larger reservoir such as a garden or gravel tray without drainage holes. The pot is removed from the reservoir and placed in the tray, the tray is then filled with water up to the height that nutrient solution is usually added. It's best to not do this too often as the larger reservoir means that the aggregate will stay wet for longer and some plants like to dry out slightly between watering.
Links
Regal Orchids
A supplier of orchid plants and related products, based in Scotland. Regal Orchids stock 'Hydropots' which consist of an outer pot (vase), inner pot (culture pot) and water level indicator. So, if you're keen to try hydroculture but not keen on the homemade methods described above then these kits may be the solution.
PurLec Hydroculture
A very friendly company who supplied me with a list of plants suitable for hydroculture. Their site contains lots of hydroculture products and very useful information.
Water Roots
A very informative and well laid out site with many photos of plants in hydroculture. The author of this site uses glass containers to contain the aggregate and nutrients. This method provides a very attractive alternative to pots while allowing easy checking of water level. Check out "The Hydro Log" page while you're there, I find it a great read.
How to grow house plants in water
A lens site written by a fellow hydroculture enthusiast. This lens explains hydroculture, helps you get started, and provides valuable resources.
Wikipedia
Hydroponics information on Wikipedia [opens a new browser window].
Answers.com
Hydroponics information on Answers.com
The Flowers & Plants Association
Although not a hydroculture site, this site contains a lot of information on houseplants, including facts, care tips, plant trends and decor. There is also a section on the health benefits of plants.
Agriculture
Agriculture is the production of food and goods through farming. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants (i.e. crops) creating food surpluses that enabled the development of more densely populated and stratified societies. The study of agriculture is known as agricultural science. Agriculture is also observed in certain species of ant and termite.
Agriculture encompasses a wide variety of specialties and techniques, including ways to expand the lands suitable for plant raising, by digging water-channels and other forms of irrigation. Cultivation of crops on arable land and the pastoral herding of livestock on rangeland remain at the foundation of agriculture. In the past century there has been increasing concern to identify and quantify various forms of agriculture. In the developed world the range usually extends between sustainable agriculture (e.g. permaculture or organic agriculture) and intensive farming (e.g. industrial agriculture).
Modern agronomy, plant breeding, pesticides and fertilizers, and technological improvements have sharply increased yields from cultivation, and at the same time have caused widespread ecological damage and negative human health effects.Selective breeding and modern practices in animal husbandry such as intensive pig farming (and similar practices applied to the chicken) have similarly increased the output of meat, but have raised concerns about animal cruelty and the health effects of the antibiotics, growth hormones, and other chemicals commonly used in industrial meat production.
The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. In the 2000s, plants have been used to grow biofuels, biopharmaceuticals, bioplastics, and pharmaceuticals.Specific foods include cereals, vegetables, fruits, and meat. Fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo. Other useful materials are produced by plants, such as resins. Biofuels include methane from biomass, ethanol, and biodiesel. Cut flowers, nursery plants, tropical fish and birds for the pet trade are some of the ornamental products.
In 2007, about one third of the world's workers were employed in agriculture. The services sector has overtaken agriculture as the economic sector employing the most people worldwide. Despite the size of its workforce, agricultural production accounts for less than five percent of the gross world product (an aggregate of all gross domestic products).
Etymology
The word agriculture is the English adaptation of Latin agricultūra, from ager, "a field", and cultūra, "cultivation" in the strict sense of "tillage of the soil". Thus, a literal reading of the word yields "tillage of a field / of fields"...
[edit] Overview
Agriculture has played a key role in the development of human civilization. Until the Industrial Revolution, the vast majority of the human population labored in agriculture. Development of agricultural techniques has steadily increased agricultural productivity, and the widespread diffusion of these techniques during a time period is often called an agricultural revolution. A remarkable shift in agricultural practices has occurred over the past century in response to new technologies. In particular, the Haber-Bosch method for synthesizing ammonium nitrate made the traditional practice of recycling nutrients with crop rotation and animal manure less necessary.
The percent of the human population working in agriculture has decreased over time.
Synthetic nitrogen, along with mined rock phosphate, pesticides and mechanization, have greatly increased crop yields in the early 20th century. Increased supply of grains has led to cheaper livestock as well. Further, global yield increases were experienced later in the 20th century when high-yield varieties of common staple grains such as rice, wheat, and corn (maize) were introduced as a part of the Green Revolution. The Green Revolution exported the technologies (including pesticides and synthetic nitrogen) of the developed world to the developing world. Thomas Malthus famously predicted that the Earth would not be able to support its growing population, but technologies such as the Green Revolution have allowed the world to produce a surplus of food.
Agricultural output in 2005.
Many governments have subsidized agriculture to ensure an adequate food supply. These agricultural subsidies are often linked to the production of certain commodities such as wheat, corn (maize), rice, soybeans, and milk. These subsidies, especially when instituted by developed countries have been noted as protectionist, inefficient, and environmentally damaging. In the past century agriculture has been characterized by enhanced productivity, the use of synthetic fertilizers and pesticides, selective breeding, mechanization, water contamination, and farm subsidies. Proponents of organic farming such as Sir Albert Howard argued in the early 1900s that the overuse of pesticides and synthetic fertilizers damages the long-term fertility of the soil. While this feeling lay dormant for decades, as environmental awareness has increased in the 2000s there has been a movement towards sustainable agriculture by some farmers, consumers, and policymakers. In recent years there has been a backlash against perceived external environmental effects of mainstream agriculture, particularly regarding water pollution, resulting in the organic movement. One of the major forces behind this movement has been the European Union, which first certified organic food in 1991 and began reform of its Common Agricultural Policy (CAP) in 2005 to phase out commodity-linked farm subsidies, also known as decoupling. The growth of organic farming has renewed research in alternative technologies such as integrated pest management and selective breeding. Recent mainstream technological developments include genetically modified food.
In late 2007, several factors pushed up the price of grains consumed by humans as well as used to feed poultry and dairy cows and other cattle, causing higher prices of wheat (up 58%), soybean (up 32%), and maize (up 11%) over the year. Food riots took place in several countries across the world. Contributing factors included drought in Australia and elsewhere, increasing demand for grain-fed animal products from the growing middle classes of countries such as China and India, diversion of foodgrain to biofuel production and trade restrictions imposed by several countries.
An epidemic of stem rust on wheat caused by race Ug99 is currently spreading across Africa and into Asia and is causing major concern. Approximately 40% of the world's agricultural land is seriously degraded.In Africa, if current trends of soil degradation continue, the continent might be able to feed just 25% of its population by 2025, according to UNU's Ghana-based Institute for Natural Resources in Africa.
[edit] History
Main article: History of agriculture
A Sumerian harvester's sickle made from baked clay (ca. 3000 BC).
Since its development roughly 10,000 years ago,agriculture has expanded vastly in geographical coverage and yields. Throughout this expansion, new technologies and new crops were integrated. Even then crops were modified through cross-breeding for better yields. Agricultural practices such as irrigation, crop rotation, fertilizers, and pesticides were developed long ago, but have made great strides in the past century. The history of agriculture has played a major role in human history, as agricultural progress has been a crucial factor in worldwide socio-economic change. Wealth-concentration and militaristic specializations rarely seen in hunter-gatherer cultures are commonplace in societies which practice agriculture. So, too, are arts such as epic literature and monumental architecture, as well as codified legal systems. When farmers became capable of producing food beyond the needs of their own families, others in their society were freed to devote themselves to projects other than food acquisition. Historians and anthropologists have long argued that the development of agriculture made civilization possible.
[edit] Ancient origins
Further information: Neolithic Revolution
The Fertile Crescent of Western Asia, Egypt, and India were sites of the earliest planned sowing and harvesting of plants that had previously been gathered in the wild. Independent development of agriculture occurred in northern and southern China, Africa's Sahel, New Guinea and several regions of the Americas. The eight so-called Neolithic founder crops of agriculture appear: first emmer wheat and einkorn wheat, then hulled barley, peas, lentils, bitter vetch, chick peas and flax.
By 7000 BC, small-scale agriculture reached Egypt. From at least 7000 BC the Indian subcontinent saw farming of wheat and barley, as attested by archaeological excavation at Mehrgarh in Balochistan. By 6000 BC, mid-scale farming was entrenched on the banks of the Nile. About this time, agriculture was developed independently in the Far East, with rice, rather than wheat, as the primary crop. Chinese and Indonesian farmers went on to domesticate taro and beans including mung, soy and azuki. To complement these new sources of carbohydrates, highly organized net fishing of rivers, lakes and ocean shores in these areas brought in great volumes of essential protein. Collectively, these new methods of farming and fishing inaugurated a human population boom that dwarfed all previous expansions and continues today.
By 5000 BC, the Sumerians had developed core agricultural techniques including large-scale intensive cultivation of land, monocropping, organized irrigation, and the use of a specialized labor force, particularly along the waterway now known as the Shatt al-Arab, from its Persian Gulf delta to the confluence of the Tigris and Euphrates. Domestication of wild aurochs and mouflon into cattle and sheep, respectively, ushered in the large-scale use of animals for food/fiber and as beasts of burden. The shepherd joined the farmer as an essential provider for sedentary and seminomadic societies. Maize, manioc, and arrowroot were first domesticated in the Americas as far back as 5200 BC.[25] The potato, tomato, pepper, squash, several varieties of bean, tobacco, and several other plants were also developed in the New World, as was extensive terracing of steep hillsides in much of Andean South America. The Greeks and Romans built on techniques pioneered by the Sumerians, but made few fundamentally new advances. Southern Greeks struggled with very poor soils, yet managed to become a dominant society for years. The Romans were noted for an emphasis on the cultivation of crops for trade.
The Harvesters. Pieter Bruegel. 1565.
In the Americas, a parallel agricultural revolution occurred, resulting in some of the most important crops grown today. In Mesoamerica wild teosinte was transformed through human selection into the ancestor of modern maize, more than 6000 years ago. It gradually spread across North America and was the major crop of Native Americans at the time of European exploration. Other Mesoamerican crops include hundreds of varieties of squash and beans. Cocoa was also a major crop in domesticated Mexico and Central America. The turkey, one of the most important meat birds, was probably domesticated in Mexico or the U.S. Southwest. In the Andes region of South America the major domesticated crop was potatoes, domesticated perhaps 5000 years ago. Large varieties of beans were domesticated, in South America, as well as animals, including llamas, alpacas, and guinea pigs. Coca, still a major crop, was also domesticated in the Andes. A minor center of domestication, the indigenous people of the Eastern U.S. appear to have domesticated numerous crops. Sunflowers, tobacco, varieties of squash and Chenopodium, as well as crops no longer grown, including marshelder and little barley were domesticated. Other wild foods may have undergone some selective cultivation, including wild rice and maple sugar. The most common varieties of strawberry were domesticated from Eastern North America.
Middle Ages
During the Middle Ages, farmers in North Africa, the Near East, and Europe began making use of agricultural technologies including irrigation systems based on hydraulic and hydrostatic principles, machines such as norias, water-raising machines, dams, and reservoirs. This combined with the invention of a three-field system of crop rotation and the moldboard plow greatly improved agricultural efficiency.
Modern era
Further information: British Agricultural Revolution and Green Revolution
This photo from a 1921 encyclopedia shows a tractor ploughing an alfalfa field.
Satellite image of farming in Minnesota.
Infrared image of the above farms. To the untrained eye, this image appears a hodge-podge of colours without any apparent purpose. But farmers are now trained to see yellows where crops are infested, shades of red indicating crop health, black where flooding occurs, and brown where unwanted pesticides land on chemical-free crops.
After 1492, a global exchange of previously local crops and livestock breeds occurred. Key crops involved in this exchange included the tomato, maize, potato, manioc, cocoa bean and tobacco going from the New World to the Old, and several varieties of wheat, spices, coffee, and sugar cane going from the Old World to the New. The most important animal exportation from the Old World to the New were those of the horse and dog (dogs were already present in the pre-Columbian Americas but not in the numbers and breeds suited to farm work). Although not usually food animals, the horse (including donkeys and ponies) and dog quickly filled essential production roles on western-hemisphere farms.
The potato became an important staple crop in northern Europe.Since being introduced by Portuguese in the 16th century, maize and manioc have replaced traditional African crops as the continent's most important staple food crops.
By the early 1800s, agricultural techniques, implements, seed stocks and cultivated plants selected and given a unique name because of its decorative or useful characteristics had so improved that yield per land unit was many times that seen in the Middle Ages. With the rapid rise of mechanization in the late 19th and 20th centuries, particularly in the form of the tractor, farming tasks could be done with a speed and on a scale previously impossible. These advances have led to efficiencies enabling certain modern farms in the United States, Argentina, Israel, Germany, and a few other nations to output volumes of high-quality produce per land unit at what may be the practical limit. The Haber-Bosch method for synthesizing ammonium nitrate represented a major breakthrough and allowed crop yields to overcome previous constraints. In the past century agriculture has been characterized by enhanced productivity, the substitution of labor for synthetic fertilizers and pesticides, water pollution, and farm subsidies. In recent years there has been a backlash against the external environmental effects of conventional agriculture, resulting in the organic movement.
The cereals rice, corn, and wheat provide 60% of human food supply.Between 1700 and 1980, "the total area of cultivated land worldwide increased 466%" and yields increased dramatically, particularly because of selectively bred high-yielding varieties, fertilizers, pesticides, irrigation, and machinery.For example, irrigation increased corn yields in eastern Colorado by 400 to 500% from 1940 to 1997
However, concerns have been raised over the sustainability of intensive agriculture. Intensive agriculture has become associated with decreased soil quality in India and Asia, and there has been increased concern over the effects of fertilizers and pesticides on the environment, particularly as population increases and food demand expands. The monocultures typically used in intensive agriculture increase the number of pests, which are controlled through pesticides. Integrated pest management (IPM), which "has been promoted for decades and has had some notable successes" has not significantly affected the use of pesticides because policies encourage the use of pesticides and IPM is knowledge-intensive.Although the "Green Revolution" significantly increased rice yields in Asia, yield increases have not occurred in the past 15–20 years. The genetic "yield potential" has increased for wheat, but the yield potential for rice has not increased since 1966, and the yield potential for maize has "barely increased in 35 years". It takes a decade or two for herbicide-resistant weeds to emerge, and insects become resistant to insecticides within about a decade. Crop rotation helps to prevent resistances.
Agricultural exploration expeditions, since the late nineteenth century, have been mounted to find new species and new agricultural practices in different areas of the world. Two early examples of expeditions include Frank N. Meyer's fruit- and nut-collecting trip to China and Japan from 1916-1918 and the Dorsett-Morse Oriental Agricultural Exploration Expedition to China, Japan, and Korea from 1929-1931 to collect soybean germplasm to support the rise in soybean agriculture in the United States.
In 2005, the agricultural output of China was the largest in the world, accounting for almost one-sixth of world share, followed by the EU, India and the USA, according to the International Monetary Fund.[citation needed] More than 40 million Chinese farmers have been displaced from their land in recent years, usually for economic development, contributing to the 87,000 demonstrations and riots across China in 2005. Economists measure the total factor productivity of agriculture and by this measure agriculture in the United States is roughly 2.6 times more productive than it was in 1948.
Six countries - the US, Canada, France, Australia, Argentina and Thailand - supply 90% of grain exports.The United States controls almost half of world grain exports. Water deficits, which are already spurring heavy grain imports in numerous middle-sized countries, including Algeria, Iran, Egypt, and Mexico,may soon do the same in larger countries, such as China or India.
Crop production systems
Farmers work inside a rice field in Andhra Pradesh, India.
Cropping systems vary among farms depending on the available resources and constraints; geography and climate of the farm; government policy; economic, social and political pressures; and the philosophy and culture of the farmer. Shifting cultivation (or slash and burn) is a system in which forests are burnt, releasing nutrients to support cultivation of annual and then perennial crops for a period of several years. Then the plot is left fallow to regrow forest, and the farmer moves to a new plot, returning after many more years (10-20). This fallow period is shortened if population density grows, requiring the input of nutrients (fertilizer or manure) and some manual pest control. Annual cultivation is the next phase of intensity in which there is no fallow period. This requires even greater nutrient and pest control inputs. Further industrialization lead to the use of monocultures, when one cultivar is planted on a large acreage. Because of the low biodiversity, nutrient use is uniform and pests tend to build up, necessitating the greater use of pesticides and fertilizers.[44] Multiple cropping, in which several crops are grown sequentially in one year, and intercropping, when several crops are grown at the same time are other kinds of annual cropping systems known as polycultures.
In tropical environments, all of these cropping systems are practiced. In subtropical and arid environments, the timing and extent of agriculture may be limited by rainfall, either not allowing multiple annual crops in a year, or requiring irrigation. In all of these environments perennial crops are grown (coffee, chocolate) and systems are practiced such as agroforestry. In temperate environments, where ecosystems were predominantly grassland or prairie, highly productive annual cropping is the dominant farming system.
The last century has seen the intensification, concentration and specialization of agriculture, relying upon new technologies of agricultural chemicals (fertilizers and pesticides), mechanization, and plant breeding (hybrids and GMO's). In the past few decades, a move towards sustainability in agriculture has also developed, integrating ideas of socio-economic justice and conservation of resources and the environment within a farming system. This has led to the development of many responses to the conventional agriculture approach, including organic agriculture, urban agriculture, community supported agriculture, ecological or biological agriculture, integrated farming and holistic management, as well as an increased trend towards agricultural diversification.
Crop statistics
Important categories of crops include grains and pseudograins, pulses (legumes), forage, and fruits and vegetables. Specific crops are cultivated in distinct growing regions throughout the world. In millions of metric tons, based on FAO estimate.
Top agricultural products, by crop types
(million metric tons) 2004 data
Cereals 2,263
Vegetables and melons 866
Roots and Tubers 715
Milk 619
Fruit 503
Meat 259
Oilcrops 133
Fish (2001 estimate) 130
Eggs 63
Pulses 60
Vegetable Fiber 30
Source:
Food and Agriculture Organization (FAO)[48]
Top agricultural products, by individual crops
(million metric tons) 2004 data
Sugar Cane 1,324
Maize 721
Wheat 627
Rice 605
Potatoes 328
Sugar Beet 249
Soybean 204
Oil Palm Fruit 162
Barley 154
Tomato 120
Source:
Food and Agriculture Organization (FAO)
Livestock production systems
Main article: Livestock
Ploughing rice paddies with water buffalo, in Indonesia.
Animals, including horses, mules, oxen, camels, llamas, alpacas, and dogs, are often used to help cultivate fields, harvest crops, wrangle other animals, and transport farm products to buyers. Animal husbandry not only refers to the breeding and raising of animals for meat or to harvest animal products (like milk, eggs, or wool) on a continual basis, but also to the breeding and care of species for work and companionship. Livestock production systems can be defined based on feed source, as grassland - based, mixed, and landless.Grassland based livestock production relies upon plant material such as shrubland, rangeland, and pastures for feeding ruminant animals. Outside nutrient inputs may be used, however manure is returned directly to the grassland as a major nutrient source. This system is particularly important in areas where crop production is not feasible because of climate or soil, representing 30-40 million pastoralists. Mixed production systems use grassland, fodder crops and grain feed crops as feed for ruminant and monogastic (one stomach; mainly chickens and pigs) livestock. Manure is typically recycled in mixed systems as a fertilizer for crops. Approximately 68% of all agricultural land is permanent pastures used in the production of livestock.[50] Landless systems rely upon feed from outside the farm, representing the de-linking of crop and livestock production found more prevalently in OECD member countries. In the U.S., 70% of the grain grown is fed to animals on feedlots.[45] Synthetic fertilizers are more heavily relied upon for crop production and manure utilization becomes a challenge as well as a source for pollution.
[edit] Production practices
Road leading across the farm allows machinery access to the farm for production practices.
Tillage is the practice of plowing soil to prepare for planting or for nutrient incorporation or for pest control. Tillage varies in intensity from conventional to no-till. It may improve productivity by warming the soil, incorporating fertilizer and controlling weeds, but also renders soil more prone to erosion, triggers the decomposition of organic matter releasing CO2, and reduces the abundance and diversity of soil organisms.
Pest control includes the management of weeds, insects/mites, and diseases. Chemical (pesticides), biological (biocontrol), mechanical (tillage), and cultural practices are used. Cultural practices include crop rotation, culling, cover crops, intercropping, composting, avoidance, and resistance. Integrated pest management attempts to use all of these methods to keep pest populations below the number which would cause economic loss, and recommends pesticides as a last resort.
Nutrient management includes both the source of nutrient inputs for crop and livestock production, and the method of utilization of manure produced by livestock. Nutrient inputs can be chemical inorganic fertilizers, manure, green manure, compost and mined minerals.Crop nutrient use may also be managed using cultural techniques such as crop rotation or a fallow period.Manure is used either by holding livestock where the feed crop is growing, such as in managed intensive rotational grazing, or by spreading either dry or liquid formulations of manure on cropland or pastures.
Water management is where rainfall is insufficient or variable, which occurs to some degree in most regions of the world. Some farmers use irrigation to supplement rainfall. In other areas such as the Great Plains in the U.S. and Canada, farmers use a fallow year to conserve soil moisture to use for growing a crop in the following year. Agriculture represents 70% of freshwater use worldwide.
Processing, distribution, and marketing
Main article: Food processing
Main article: Agricultural marketing
In the United States, food costs attributed to processing, distribution, and marketing have risen while the costs attributed to farming have declined. This is related to the greater efficiency of farming, combined with the increased level of value addition (e.g. more highly processed products) provided by the supply chain. From 1960 to 1980 the farm share was around 40%, but by 1990 it had declined to 30% and by 1998, 22.2%. Market concentration has increased in the sector as well, with the top 20 food manufacturers accounting for half the food-processing value in 1995, over double that produced in 1954. As of 2000 the top six US supermarket groups had 50% of sales compared to 32% in 1992. Although the total effect of the increased market concentration is likely increased efficiency, the changes redistribute economic surplus from producers (farmers) and consumers, and may have negative implications for rural communities.
Crop alteration and biotechnology
Main article: Plant breeding
Tractor and Chaser bin.
Crop alteration has been practiced by humankind for thousands of years, since the beginning of civilization. Altering crops through breeding practices changes the genetic make-up of a plant to develop crops with more beneficial characteristics for humans, for example, larger fruits or seeds, drought-tolerance, or resistance to pests. Significant advances in plant breeding ensued after the work of geneticist Gregor Mendel. His work on dominant and recessive alleles gave plant breeders a better understanding of genetics and brought great insights to the techniques utilized by plant breeders. Crop breeding includes techniques such as plant selection with desirable traits, self-pollination and cross-pollination, and molecular techniques that genetically modify the organism. Domestication of plants has, over the centuries increased yield, improved disease resistance and drought tolerance, eased harvest and improved the taste and nutritional value of crop plants. Careful selection and breeding have had enormous effects on the characteristics of crop plants. Plant selection and breeding in the 1920s and 1930s improved pasture (grasses and clover) in New Zealand. Extensive X-ray an ultraviolet induced mutagenesis efforts (i.e. primitive genetic engineering) during the 1950s produced the modern commercial varieties of grains such as wheat, corn (maize) and barley.
The green revolution popularized the use of conventional hybridization to increase yield many folds by creating "high-yielding varieties". For example, average yields of corn (maize) in the USA have increased from around 2.5 tons per hectare (t/ha) (40 bushels per acre) in 1900 to about 9.4 t/ha (150 bushels per acre) in 2001. Similarly, worldwide average wheat yields have increased from less than 1 t/ha in 1900 to more than 2.5 t/ha in 1990. South American average wheat yields are around 2 t/ha, African under 1 t/ha, Egypt and Arabia up to 3.5 to 4 t/ha with irrigation. In contrast, the average wheat yield in countries such as France is over 8 t/ha. Variations in yields are due mainly to variation in climate, genetics, and the level of intensive farming techniques (use of fertilizers, chemical pest control, growth control to avoid lodging).
Genetic Engineering
Main article: Genetic Engineering
Genetically Modified Organisms (GMO) are organisms whose genetic material has been altered by genetic engineering techniques generally known as recombinant DNA technology. Genetic engineering has expanded the genes available to breeders to utilize in creating desired germlines for new crops. After mechanical tomato-harvesters were developed in the early 1960s, agricultural scientists genetically modified tomatoes to be more resistant to mechanical handling. More recently, genetic engineering is being employed in various parts of the world, to create crops with other beneficial traits.
[edit] Herbicide-tolerant GMO Crops
Roundup Ready seed has a herbicide resistant gene implanted into its genome that allows the plants to tolerate exposure to glyphosate. Roundup is a trade name for a glyphosate-based product, which is a systemic, nonselective herbicide used to kill weeds. Roundup Ready seeds allow the farmer to grow a crop that can be sprayed with glyphosate to control weeds without harming the resistant crop. Herbicide-tolerant crops are used by farmers worldwide. Today, 92% of soybean acreage in the US is planted with genetically modified herbicide-tolerant plants.[66] With the increasing use of herbicide-tolerant crops, comes an increase in the use of glyphosate-based herbicide sprays. In some areas glyphosate resistant weeds have developed, causing farmers to switch to other herbicides.[67][68] Some studies also link widespread glyphosate usage to iron deficiencies in some crops, which is both a crop production and a nutritional quality concern, with potential economic and health implications.
Insect-Resistant GMO Crops
Other GMO crops used by growers include insect-resistant crops, which have a gene from the soil bacterium Bacillus thuringiensis (Bt), which produces a toxin specific to insects. These crops protect plants from damage by insects; one such crop is Starlink. Another is cotton, which accounts for 63% of US cotton acreage.
Some believe that similar or better pest-resistance traits can be acquired through traditional breeding practices, and resistance to various pests can be gained through hybridization or cross-pollination with wild species. In some cases, wild species are the primary source of resistance traits; some tomato cultivars that have gained resistance to at least nineteen diseases did so through crossing with wild populations of tomatoes.
Costs and Benefits of GMOs
Genetic engineers may someday develop transgenic plants which would allow for irrigation, drainage, conservation, sanitary engineering, and maintaining or increasing yields while requiring fewer fossil fuel derived inputs than conventional crops. Such developments would be particularly important in areas which are normally arid and rely upon constant irrigation, and on large scale farms. However, genetic engineering of plants has proven to be controversial. Many issues surrounding food security and environmental impacts have risen regarding GMO practices. For example, GMOs are questioned by some ecologists and economists concerned with GMO practices such as terminator seeds, which is a genetic modification that creates sterile seeds. Terminator seeds are currently under strong international opposition and face continual efforts of global bans. Another controversial issue is the patent protection given to companies that develop new types of seed using genetic engineering. Since companies have intellectual ownership of their seeds, they have the power to dictate terms and conditions of their patented product. Currently, ten seed companies control over two-thirds of the global seed sales. Vandana Shiva argues that these companies are guilty of biopiracy by patenting life and exploiting organisms for profit Farmers using patented seed are restricted from saving seed for subsequent plantings, which forces farmers to buy new seed every year. Since seed saving is a traditional practice for many farmers in both developing and developed countries, GMO seeds legally bind farmers to change their seed saving practices to buying new seed every year.
Locally adapted seeds are an essential hertitage that has the potential to be lost with current hybridized crops and GMOs. Locally adapted seeds, also called land races or crop eco-types, are important because they have adapted over time to the specific microclimates, soils, other environmental conditions, field designs, and ethnic preference indigenous to the exact area of cultivation. Introducing GMOs and hybridized commercial seed to an area brings the risk of cross-pollination with local land races Therefore, GMOs pose a threat to the sustainability of land races and the ethnic heritage of cultures. Once seed contains transgenic material, it becomes subject to the conditions of the seed company that owns the patent of the transgenic material.
There is also concern that GMOs will cross-pollinate with wild species and permanently alter native populations’ genetic integrity; there are already identified populations of wild plants with transgenic genes. GMO gene flow to related weed species is a concern, as well as cross-pollination with non-transgenic crops. Since many GMO crops are harvested for their seed, such as rapeseed, seed spillage in is problematic for volunteer plants in rotated fields, as well as seed-spillage during transportation.
Food safety and labeling
Food security issues also coincide with food safety and food labeling concerns. Currently a global treaty, the BioSafety Protocol, regulates the trade of GMOs. The EU currently requires all GMO foods to be labeled, whereas the US does not require transparent labeling of GMO foods. Since there are still questions regarding the safety and risks associated with GMO foods, some believe the public should have the freedom to choose and know what they are eating and require all GMO products to be labeled.
Environmental impact
Main article: Environmental issues with agriculture
Agriculture imposes external costs upon society through pesticides, nutrient runoff, excessive water usage, and assorted other problems. A 2000 assessment of agriculture in the UK determined total external costs for 1996 of £2,343 million, or £208 per hectare.[81] A 2005 analysis of these costs in the USA concluded that cropland imposes approximately $5 to 16 billion ($30 to $96 per hectare), while livestock production imposes $714 million.[82] Both studies concluded that more should be done to internalize external costs, and neither included subsidies in their analysis, but noted that subsidies also influence the cost of agriculture to society. Both focused on purely fiscal impacts. The 2000 review included reported pesticide poisonings but did not include speculative chronic effects of pesticides, and the 2004 review relied on a 1992 estimate of the total impact of pesticides.
A key player who is credited to saving billions of lives because of his revolutionary work in developing new agricultural techniques is Norman Borlaug. His transformative work brought high-yield crop varieties to developing countries and earned him an unofficial title as the father of the Green Revolution.
Livestock issues
A senior UN official and co-author of a UN report detailing this problem, Henning Steinfeld, said "Livestock are one of the most significant contributors to today's most serious environmental problems".[83] Livestock production occupies 70% of all land used for agriculture, or 30% of the land surface of the planet. It is one of the largest sources of greenhouse gases, responsible for 18% of the world's greenhouse gas emissions as measured in CO2 equivalents. By comparison, all transportation emits 13.5% of the CO2. It produces 65% of human-related nitrous oxide (which has 296 times the global warming potential of CO2,) and 37% of all human-induced methane (which is 23 times as warming as CO2. It also generates 64% of the ammonia, which contributes to acid rain and acidification of ecosystems. Livestock expansion is cited as a key factor driving deforestation, in the Amazon basin 70% of previously forested area is now occupied by pastures and the remainder used for feedcrops.[84] Through deforestation and land degradation, livestock is also driving reductions in biodiversity.
Land transformation and degradation
Land transformation, the use of land to yield goods and services, is the most substantial way humans alter the Earth's ecosystems, and is considered the driving force in the loss of biodiversity. Estimates of the amount of land transformed by humans vary from 39–50%. Land degradation, the long-term decline in ecosystem function and productivity, is estimated to be occurring on 24% of land worldwide, with cropland overrepresented.[86] The UN-FAO report cites land management as the driving factor behind degradation and reports that 1.5 billion people rely upon the degrading land. Degradation can be deforestation, desertification, soil erosion, mineral depletion, or chemical degradation (acidification and salinization).
Eutrophication
Eutrophication, excessive nutrients in aquatic ecosystems resulting in algal blooms and anoxia, leads to fish kills, loss of biodiversity, and renders water unfit for drinking and other industrial uses. Excessive fertilization and manure application to cropland, as well as high livestock stocking densities cause nutrient (mainly nitrogen and phosphorus) runoff and leaching from agricultural land. These nutrients are major nonpoint pollutants contributing to eutrophication of aquatic ecosystems.
Pesticides
Pesticide use has increased since 1950 to 2.5 million tons annually worldwide, yet crop loss from pests has remained relatively constant. The World Health Organization estimated in 1992 that 3 million pesticide poisonings occur annually, causing 220,000 deaths.[89] Pesticides select for pesticide resistance in the pest population, leading to a condition termed the 'pesticide treadmill' in which pest resistance warrants the development of a new pesticide.An alternative argument is that the way to 'save the environment' and prevent famine is by using pesticides and intensive high yield farming, a view exemplified by a quote heading the Center for Global Food Issues website: 'Growing more per acre leaves more land for nature'. However, critics argue that a trade-off between the environment and a need for food is not inevitable,and that pesticides simply replace good agronomic practices such as crop rotation.
Climate Change
Climate change has the potential to affect agriculture through changes in temperature, rainfall (timing and quantity), CO2, solar radiation and the interaction of these elements. Agriculture can both mitigate or worsen global warming. Some of the increase in CO2 in the atmosphere comes from the decomposition of organic matter in the soil, and much of the methane emitted into the atmosphere is caused by the decomposition of organic matter in wet soils such as rice paddies.[95] Further, wet or anaerobic soils also lose nitrogen through denitrification, releasing the greenhouse gas nitric oxide. Changes in management can reduce the release of these greenhouse gases, and soil can further be used to sequester some of the CO2 in the atmosphere.
Distortions in modern global agriculture
See also: Agricultural subsidy
Differences in economic development, population density and culture mean that the farmers of the world operate under very different conditions.
A US cotton farmer may receive US$230 in government subsidies per acre planted (in 2003), while farmers in Mali and other third-world countries do without. When prices decline, the heavily subsidised US farmer is not forced to reduce his output, making it difficult for cotton prices to rebound, but his Mali counterpart may go broke in the meantime.
A livestock farmer in South Korea can calculate with a (highly subsidized) sales price of US$1300 for a calf produced. A South American Mercosur country rancher calculates with a calf's sales price of US$120–200 (both 2008 figures). With the former, scarcity and high cost of land is compensated with public subsidies, the latter compensates absence of subsidies with economics of scale and low cost of land.
In the Peoples Republic of China, a rural household's productive asset may be one hectare of farmland.In Brazil, Paraguay and other countries where local legislature allows such purchases, international investors buy thousands of hectares of farmland or raw land at prices of a few hundred US$ per hectare.
Energy and agriculture
Since the 1940s, agricultural productivity has increased dramatically, due largely to the increased use of energy-intensive mechanization, fertilizers and pesticides. The vast majority of this energy input comes from fossil fuel sources. Between 1950 and 1984, the Green Revolution transformed agriculture around the globe, with world grain production increasing by 250% as world population doubled. Modern agriculture's heavy reliance on petrochemicals and mechanization has raised concerns that oil shortages could increase costs and reduce agricultural output, causing food shortages.
Agriculture and food system share (%) of total energy
consumption by three industrialized nations
Country Year Agriculture
(direct & indirect) Food
system
United Kingdom 2005 1.9 11
United States of America 1996 2.1 10
Sweden 2000 2.5 13
Modern or industrialized agriculture is dependent on fossil fuels in two fundamental ways: 1) direct consumption on the farm and 2) indirect consumption to manufacture inputs used on the farm. Direct consumption includes the use of lubricants and fuels to operate farm vehicles and machinery; and use of gas, liquid propane, and electricity to power dryers, pumps, lights, heaters, and coolers. American farms directly consumed about 1.2 exajoules (1.1 quadrillion BTU) in 2002, or just over 1 percent of the nation's total energy.Indirect consumption is mainly oil and natural gas used to manufacture fertilizers and pesticides, which accounted for 0.6 exajoules (0.6 quadrillion BTU) in 2002.The energy used to manufacture farm machinery is also a form of indirect agricultural energy consumption, but it is not included in USDA estimates of U.S. agricultural energy use. Together, direct and indirect consumption by U.S. farms accounts for about 2 percent of the nation's energy use. Direct and indirect energy consumption by U.S. farms peaked in 1979, and has gradually declined over the past 30 years.
Food systems encompass not just agricultural production, but also off-farm processing, packaging, transporting, marketing, consumption, and disposal of food and food-related items. Agriculture accounts for approximately one-fifth of food system energy use in the United States.
Oil shortages could impact this food supply. Some farmers using modern organic-farming methods have reported yields as high as those available from conventional farming without the use of synthetic fertilizers and pesticides. However, the reconditioning of soil to restore nutrients lost during the use of monoculture agriculture techniques made possible by petroleum-based technology takes time.
Unbalanced scales.svg
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In 2007, higher incentives for farmers to grow non-food biofuel cropscombined with other factors (such as over-development of former farm lands, rising transportation costs, climate change, growing consumer demand in China and India, and population growth) to cause food shortages in Asia, the Middle East, Africa, and Mexico, as well as rising food prices around the globe.As of December 2007, 37 countries faced food crises, and 20 had imposed some sort of food-price controls. Some of these shortages resulted in food riots and even deadly stampedes.
The biggest fossil fuel input to agriculture is the use of natural gas as a hydrogen source for the Haber-Bosch fertilizer-creation process.Natural gas is used because it is the cheapest currently available source of hydrogen. When oil production becomes so scarce that natural gas is used as a partial stopgap replacement, and hydrogen use in transportation increases, natural gas will become much more expensive. If the Haber Process is unable to be commercialized using renewable energy (such as by electrolysis) or if other sources of hydrogen are not available to replace the Haber Process, in amounts sufficient to supply transportation and agricultural needs, this major source of fertilizer would either become extremely expensive or unavailable. This would either cause food shortages or dramatic rises in food prices.
Mitigation of effects of petroleum shortages
One effect oil shortages could have on agriculture is a full return to organic agriculture. In light of peak-oil concerns, organic methods are more sustainable than contemporary practices because they use no petroleum-based pesticides, herbicides, or fertilizers. Some farmers using modern organic-farming methods have reported yields as high as those available from conventional farming.Organic farming may however be more labor-intensive and would require a shift of the workforce from urban to rural areas.
It has been suggested that rural communities might obtain fuel from the biochar and synfuel process, which uses agricultural waste to provide charcoal fertilizer, some fuel and food, instead of the normal food vs fuel debate. As the synfuel would be used on-site, the process would be more efficient and might just provide enough fuel for a new organic-agriculture fusion.
It has been suggested that some transgenic plants may some day be developed which would allow for maintaining or increasing yields while requiring fewer fossil-fuel-derived inputs than conventional crops. The possibility of success of these programs is questioned by ecologists and economists concerned with unsustainable GMO practices such as terminator seeds, and a January 2008 report shows that GMO practices "fail to deliver environmental, social and economic benefits." While there has been some research on sustainability using GMO crops, at least one hyped and prominent multi-year attempt by Monsanto Company has been unsuccessful, though during the same period traditional breeding techniques yielded a more sustainable variety of the same crop.[128] Additionally, a survey by the bio-tech industry of subsistence farmers in Africa to discover what GMO research would most benefit sustainable agriculture only identified non-transgenic issues as areas needing to be addressed. Nevertheless, some governments in Africa continue to view investments in new transgenic technologies as an essential component of efforts to improve sustainability.
Electrical energy efficiency on farms
Main article: Electrical energy efficiency on United States farms
Policy
Main article: Agricultural policy
Agricultural policy focuses on the goals and methods of agricultural production. At the policy level, common goals of agriculture include:
* Conservation
* Economic stability
* Environmental impact
* Food quality: Ensuring that the food supply is of a consistent and known quality.
* Food safety: Ensuring that the food supply is free of contamination.
* Food security: Ensuring that the food supply meets the population's needs.
* Poverty Reduction
Agriculture encompasses a wide variety of specialties and techniques, including ways to expand the lands suitable for plant raising, by digging water-channels and other forms of irrigation. Cultivation of crops on arable land and the pastoral herding of livestock on rangeland remain at the foundation of agriculture. In the past century there has been increasing concern to identify and quantify various forms of agriculture. In the developed world the range usually extends between sustainable agriculture (e.g. permaculture or organic agriculture) and intensive farming (e.g. industrial agriculture).
Modern agronomy, plant breeding, pesticides and fertilizers, and technological improvements have sharply increased yields from cultivation, and at the same time have caused widespread ecological damage and negative human health effects.Selective breeding and modern practices in animal husbandry such as intensive pig farming (and similar practices applied to the chicken) have similarly increased the output of meat, but have raised concerns about animal cruelty and the health effects of the antibiotics, growth hormones, and other chemicals commonly used in industrial meat production.
The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. In the 2000s, plants have been used to grow biofuels, biopharmaceuticals, bioplastics, and pharmaceuticals.Specific foods include cereals, vegetables, fruits, and meat. Fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo. Other useful materials are produced by plants, such as resins. Biofuels include methane from biomass, ethanol, and biodiesel. Cut flowers, nursery plants, tropical fish and birds for the pet trade are some of the ornamental products.
In 2007, about one third of the world's workers were employed in agriculture. The services sector has overtaken agriculture as the economic sector employing the most people worldwide. Despite the size of its workforce, agricultural production accounts for less than five percent of the gross world product (an aggregate of all gross domestic products).
Etymology
The word agriculture is the English adaptation of Latin agricultūra, from ager, "a field", and cultūra, "cultivation" in the strict sense of "tillage of the soil". Thus, a literal reading of the word yields "tillage of a field / of fields"...
[edit] Overview
Agriculture has played a key role in the development of human civilization. Until the Industrial Revolution, the vast majority of the human population labored in agriculture. Development of agricultural techniques has steadily increased agricultural productivity, and the widespread diffusion of these techniques during a time period is often called an agricultural revolution. A remarkable shift in agricultural practices has occurred over the past century in response to new technologies. In particular, the Haber-Bosch method for synthesizing ammonium nitrate made the traditional practice of recycling nutrients with crop rotation and animal manure less necessary.
The percent of the human population working in agriculture has decreased over time.
Synthetic nitrogen, along with mined rock phosphate, pesticides and mechanization, have greatly increased crop yields in the early 20th century. Increased supply of grains has led to cheaper livestock as well. Further, global yield increases were experienced later in the 20th century when high-yield varieties of common staple grains such as rice, wheat, and corn (maize) were introduced as a part of the Green Revolution. The Green Revolution exported the technologies (including pesticides and synthetic nitrogen) of the developed world to the developing world. Thomas Malthus famously predicted that the Earth would not be able to support its growing population, but technologies such as the Green Revolution have allowed the world to produce a surplus of food.
Agricultural output in 2005.
Many governments have subsidized agriculture to ensure an adequate food supply. These agricultural subsidies are often linked to the production of certain commodities such as wheat, corn (maize), rice, soybeans, and milk. These subsidies, especially when instituted by developed countries have been noted as protectionist, inefficient, and environmentally damaging. In the past century agriculture has been characterized by enhanced productivity, the use of synthetic fertilizers and pesticides, selective breeding, mechanization, water contamination, and farm subsidies. Proponents of organic farming such as Sir Albert Howard argued in the early 1900s that the overuse of pesticides and synthetic fertilizers damages the long-term fertility of the soil. While this feeling lay dormant for decades, as environmental awareness has increased in the 2000s there has been a movement towards sustainable agriculture by some farmers, consumers, and policymakers. In recent years there has been a backlash against perceived external environmental effects of mainstream agriculture, particularly regarding water pollution, resulting in the organic movement. One of the major forces behind this movement has been the European Union, which first certified organic food in 1991 and began reform of its Common Agricultural Policy (CAP) in 2005 to phase out commodity-linked farm subsidies, also known as decoupling. The growth of organic farming has renewed research in alternative technologies such as integrated pest management and selective breeding. Recent mainstream technological developments include genetically modified food.
In late 2007, several factors pushed up the price of grains consumed by humans as well as used to feed poultry and dairy cows and other cattle, causing higher prices of wheat (up 58%), soybean (up 32%), and maize (up 11%) over the year. Food riots took place in several countries across the world. Contributing factors included drought in Australia and elsewhere, increasing demand for grain-fed animal products from the growing middle classes of countries such as China and India, diversion of foodgrain to biofuel production and trade restrictions imposed by several countries.
An epidemic of stem rust on wheat caused by race Ug99 is currently spreading across Africa and into Asia and is causing major concern. Approximately 40% of the world's agricultural land is seriously degraded.In Africa, if current trends of soil degradation continue, the continent might be able to feed just 25% of its population by 2025, according to UNU's Ghana-based Institute for Natural Resources in Africa.
[edit] History
Main article: History of agriculture
A Sumerian harvester's sickle made from baked clay (ca. 3000 BC).
Since its development roughly 10,000 years ago,agriculture has expanded vastly in geographical coverage and yields. Throughout this expansion, new technologies and new crops were integrated. Even then crops were modified through cross-breeding for better yields. Agricultural practices such as irrigation, crop rotation, fertilizers, and pesticides were developed long ago, but have made great strides in the past century. The history of agriculture has played a major role in human history, as agricultural progress has been a crucial factor in worldwide socio-economic change. Wealth-concentration and militaristic specializations rarely seen in hunter-gatherer cultures are commonplace in societies which practice agriculture. So, too, are arts such as epic literature and monumental architecture, as well as codified legal systems. When farmers became capable of producing food beyond the needs of their own families, others in their society were freed to devote themselves to projects other than food acquisition. Historians and anthropologists have long argued that the development of agriculture made civilization possible.
[edit] Ancient origins
Further information: Neolithic Revolution
The Fertile Crescent of Western Asia, Egypt, and India were sites of the earliest planned sowing and harvesting of plants that had previously been gathered in the wild. Independent development of agriculture occurred in northern and southern China, Africa's Sahel, New Guinea and several regions of the Americas. The eight so-called Neolithic founder crops of agriculture appear: first emmer wheat and einkorn wheat, then hulled barley, peas, lentils, bitter vetch, chick peas and flax.
By 7000 BC, small-scale agriculture reached Egypt. From at least 7000 BC the Indian subcontinent saw farming of wheat and barley, as attested by archaeological excavation at Mehrgarh in Balochistan. By 6000 BC, mid-scale farming was entrenched on the banks of the Nile. About this time, agriculture was developed independently in the Far East, with rice, rather than wheat, as the primary crop. Chinese and Indonesian farmers went on to domesticate taro and beans including mung, soy and azuki. To complement these new sources of carbohydrates, highly organized net fishing of rivers, lakes and ocean shores in these areas brought in great volumes of essential protein. Collectively, these new methods of farming and fishing inaugurated a human population boom that dwarfed all previous expansions and continues today.
By 5000 BC, the Sumerians had developed core agricultural techniques including large-scale intensive cultivation of land, monocropping, organized irrigation, and the use of a specialized labor force, particularly along the waterway now known as the Shatt al-Arab, from its Persian Gulf delta to the confluence of the Tigris and Euphrates. Domestication of wild aurochs and mouflon into cattle and sheep, respectively, ushered in the large-scale use of animals for food/fiber and as beasts of burden. The shepherd joined the farmer as an essential provider for sedentary and seminomadic societies. Maize, manioc, and arrowroot were first domesticated in the Americas as far back as 5200 BC.[25] The potato, tomato, pepper, squash, several varieties of bean, tobacco, and several other plants were also developed in the New World, as was extensive terracing of steep hillsides in much of Andean South America. The Greeks and Romans built on techniques pioneered by the Sumerians, but made few fundamentally new advances. Southern Greeks struggled with very poor soils, yet managed to become a dominant society for years. The Romans were noted for an emphasis on the cultivation of crops for trade.
The Harvesters. Pieter Bruegel. 1565.
In the Americas, a parallel agricultural revolution occurred, resulting in some of the most important crops grown today. In Mesoamerica wild teosinte was transformed through human selection into the ancestor of modern maize, more than 6000 years ago. It gradually spread across North America and was the major crop of Native Americans at the time of European exploration. Other Mesoamerican crops include hundreds of varieties of squash and beans. Cocoa was also a major crop in domesticated Mexico and Central America. The turkey, one of the most important meat birds, was probably domesticated in Mexico or the U.S. Southwest. In the Andes region of South America the major domesticated crop was potatoes, domesticated perhaps 5000 years ago. Large varieties of beans were domesticated, in South America, as well as animals, including llamas, alpacas, and guinea pigs. Coca, still a major crop, was also domesticated in the Andes. A minor center of domestication, the indigenous people of the Eastern U.S. appear to have domesticated numerous crops. Sunflowers, tobacco, varieties of squash and Chenopodium, as well as crops no longer grown, including marshelder and little barley were domesticated. Other wild foods may have undergone some selective cultivation, including wild rice and maple sugar. The most common varieties of strawberry were domesticated from Eastern North America.
Middle Ages
During the Middle Ages, farmers in North Africa, the Near East, and Europe began making use of agricultural technologies including irrigation systems based on hydraulic and hydrostatic principles, machines such as norias, water-raising machines, dams, and reservoirs. This combined with the invention of a three-field system of crop rotation and the moldboard plow greatly improved agricultural efficiency.
Modern era
Further information: British Agricultural Revolution and Green Revolution
This photo from a 1921 encyclopedia shows a tractor ploughing an alfalfa field.
Satellite image of farming in Minnesota.
Infrared image of the above farms. To the untrained eye, this image appears a hodge-podge of colours without any apparent purpose. But farmers are now trained to see yellows where crops are infested, shades of red indicating crop health, black where flooding occurs, and brown where unwanted pesticides land on chemical-free crops.
After 1492, a global exchange of previously local crops and livestock breeds occurred. Key crops involved in this exchange included the tomato, maize, potato, manioc, cocoa bean and tobacco going from the New World to the Old, and several varieties of wheat, spices, coffee, and sugar cane going from the Old World to the New. The most important animal exportation from the Old World to the New were those of the horse and dog (dogs were already present in the pre-Columbian Americas but not in the numbers and breeds suited to farm work). Although not usually food animals, the horse (including donkeys and ponies) and dog quickly filled essential production roles on western-hemisphere farms.
The potato became an important staple crop in northern Europe.Since being introduced by Portuguese in the 16th century, maize and manioc have replaced traditional African crops as the continent's most important staple food crops.
By the early 1800s, agricultural techniques, implements, seed stocks and cultivated plants selected and given a unique name because of its decorative or useful characteristics had so improved that yield per land unit was many times that seen in the Middle Ages. With the rapid rise of mechanization in the late 19th and 20th centuries, particularly in the form of the tractor, farming tasks could be done with a speed and on a scale previously impossible. These advances have led to efficiencies enabling certain modern farms in the United States, Argentina, Israel, Germany, and a few other nations to output volumes of high-quality produce per land unit at what may be the practical limit. The Haber-Bosch method for synthesizing ammonium nitrate represented a major breakthrough and allowed crop yields to overcome previous constraints. In the past century agriculture has been characterized by enhanced productivity, the substitution of labor for synthetic fertilizers and pesticides, water pollution, and farm subsidies. In recent years there has been a backlash against the external environmental effects of conventional agriculture, resulting in the organic movement.
The cereals rice, corn, and wheat provide 60% of human food supply.Between 1700 and 1980, "the total area of cultivated land worldwide increased 466%" and yields increased dramatically, particularly because of selectively bred high-yielding varieties, fertilizers, pesticides, irrigation, and machinery.For example, irrigation increased corn yields in eastern Colorado by 400 to 500% from 1940 to 1997
However, concerns have been raised over the sustainability of intensive agriculture. Intensive agriculture has become associated with decreased soil quality in India and Asia, and there has been increased concern over the effects of fertilizers and pesticides on the environment, particularly as population increases and food demand expands. The monocultures typically used in intensive agriculture increase the number of pests, which are controlled through pesticides. Integrated pest management (IPM), which "has been promoted for decades and has had some notable successes" has not significantly affected the use of pesticides because policies encourage the use of pesticides and IPM is knowledge-intensive.Although the "Green Revolution" significantly increased rice yields in Asia, yield increases have not occurred in the past 15–20 years. The genetic "yield potential" has increased for wheat, but the yield potential for rice has not increased since 1966, and the yield potential for maize has "barely increased in 35 years". It takes a decade or two for herbicide-resistant weeds to emerge, and insects become resistant to insecticides within about a decade. Crop rotation helps to prevent resistances.
Agricultural exploration expeditions, since the late nineteenth century, have been mounted to find new species and new agricultural practices in different areas of the world. Two early examples of expeditions include Frank N. Meyer's fruit- and nut-collecting trip to China and Japan from 1916-1918 and the Dorsett-Morse Oriental Agricultural Exploration Expedition to China, Japan, and Korea from 1929-1931 to collect soybean germplasm to support the rise in soybean agriculture in the United States.
In 2005, the agricultural output of China was the largest in the world, accounting for almost one-sixth of world share, followed by the EU, India and the USA, according to the International Monetary Fund.[citation needed] More than 40 million Chinese farmers have been displaced from their land in recent years, usually for economic development, contributing to the 87,000 demonstrations and riots across China in 2005. Economists measure the total factor productivity of agriculture and by this measure agriculture in the United States is roughly 2.6 times more productive than it was in 1948.
Six countries - the US, Canada, France, Australia, Argentina and Thailand - supply 90% of grain exports.The United States controls almost half of world grain exports. Water deficits, which are already spurring heavy grain imports in numerous middle-sized countries, including Algeria, Iran, Egypt, and Mexico,may soon do the same in larger countries, such as China or India.
Crop production systems
Farmers work inside a rice field in Andhra Pradesh, India.
Cropping systems vary among farms depending on the available resources and constraints; geography and climate of the farm; government policy; economic, social and political pressures; and the philosophy and culture of the farmer. Shifting cultivation (or slash and burn) is a system in which forests are burnt, releasing nutrients to support cultivation of annual and then perennial crops for a period of several years. Then the plot is left fallow to regrow forest, and the farmer moves to a new plot, returning after many more years (10-20). This fallow period is shortened if population density grows, requiring the input of nutrients (fertilizer or manure) and some manual pest control. Annual cultivation is the next phase of intensity in which there is no fallow period. This requires even greater nutrient and pest control inputs. Further industrialization lead to the use of monocultures, when one cultivar is planted on a large acreage. Because of the low biodiversity, nutrient use is uniform and pests tend to build up, necessitating the greater use of pesticides and fertilizers.[44] Multiple cropping, in which several crops are grown sequentially in one year, and intercropping, when several crops are grown at the same time are other kinds of annual cropping systems known as polycultures.
In tropical environments, all of these cropping systems are practiced. In subtropical and arid environments, the timing and extent of agriculture may be limited by rainfall, either not allowing multiple annual crops in a year, or requiring irrigation. In all of these environments perennial crops are grown (coffee, chocolate) and systems are practiced such as agroforestry. In temperate environments, where ecosystems were predominantly grassland or prairie, highly productive annual cropping is the dominant farming system.
The last century has seen the intensification, concentration and specialization of agriculture, relying upon new technologies of agricultural chemicals (fertilizers and pesticides), mechanization, and plant breeding (hybrids and GMO's). In the past few decades, a move towards sustainability in agriculture has also developed, integrating ideas of socio-economic justice and conservation of resources and the environment within a farming system. This has led to the development of many responses to the conventional agriculture approach, including organic agriculture, urban agriculture, community supported agriculture, ecological or biological agriculture, integrated farming and holistic management, as well as an increased trend towards agricultural diversification.
Crop statistics
Important categories of crops include grains and pseudograins, pulses (legumes), forage, and fruits and vegetables. Specific crops are cultivated in distinct growing regions throughout the world. In millions of metric tons, based on FAO estimate.
Top agricultural products, by crop types
(million metric tons) 2004 data
Cereals 2,263
Vegetables and melons 866
Roots and Tubers 715
Milk 619
Fruit 503
Meat 259
Oilcrops 133
Fish (2001 estimate) 130
Eggs 63
Pulses 60
Vegetable Fiber 30
Source:
Food and Agriculture Organization (FAO)[48]
Top agricultural products, by individual crops
(million metric tons) 2004 data
Sugar Cane 1,324
Maize 721
Wheat 627
Rice 605
Potatoes 328
Sugar Beet 249
Soybean 204
Oil Palm Fruit 162
Barley 154
Tomato 120
Source:
Food and Agriculture Organization (FAO)
Livestock production systems
Main article: Livestock
Ploughing rice paddies with water buffalo, in Indonesia.
Animals, including horses, mules, oxen, camels, llamas, alpacas, and dogs, are often used to help cultivate fields, harvest crops, wrangle other animals, and transport farm products to buyers. Animal husbandry not only refers to the breeding and raising of animals for meat or to harvest animal products (like milk, eggs, or wool) on a continual basis, but also to the breeding and care of species for work and companionship. Livestock production systems can be defined based on feed source, as grassland - based, mixed, and landless.Grassland based livestock production relies upon plant material such as shrubland, rangeland, and pastures for feeding ruminant animals. Outside nutrient inputs may be used, however manure is returned directly to the grassland as a major nutrient source. This system is particularly important in areas where crop production is not feasible because of climate or soil, representing 30-40 million pastoralists. Mixed production systems use grassland, fodder crops and grain feed crops as feed for ruminant and monogastic (one stomach; mainly chickens and pigs) livestock. Manure is typically recycled in mixed systems as a fertilizer for crops. Approximately 68% of all agricultural land is permanent pastures used in the production of livestock.[50] Landless systems rely upon feed from outside the farm, representing the de-linking of crop and livestock production found more prevalently in OECD member countries. In the U.S., 70% of the grain grown is fed to animals on feedlots.[45] Synthetic fertilizers are more heavily relied upon for crop production and manure utilization becomes a challenge as well as a source for pollution.
[edit] Production practices
Road leading across the farm allows machinery access to the farm for production practices.
Tillage is the practice of plowing soil to prepare for planting or for nutrient incorporation or for pest control. Tillage varies in intensity from conventional to no-till. It may improve productivity by warming the soil, incorporating fertilizer and controlling weeds, but also renders soil more prone to erosion, triggers the decomposition of organic matter releasing CO2, and reduces the abundance and diversity of soil organisms.
Pest control includes the management of weeds, insects/mites, and diseases. Chemical (pesticides), biological (biocontrol), mechanical (tillage), and cultural practices are used. Cultural practices include crop rotation, culling, cover crops, intercropping, composting, avoidance, and resistance. Integrated pest management attempts to use all of these methods to keep pest populations below the number which would cause economic loss, and recommends pesticides as a last resort.
Nutrient management includes both the source of nutrient inputs for crop and livestock production, and the method of utilization of manure produced by livestock. Nutrient inputs can be chemical inorganic fertilizers, manure, green manure, compost and mined minerals.Crop nutrient use may also be managed using cultural techniques such as crop rotation or a fallow period.Manure is used either by holding livestock where the feed crop is growing, such as in managed intensive rotational grazing, or by spreading either dry or liquid formulations of manure on cropland or pastures.
Water management is where rainfall is insufficient or variable, which occurs to some degree in most regions of the world. Some farmers use irrigation to supplement rainfall. In other areas such as the Great Plains in the U.S. and Canada, farmers use a fallow year to conserve soil moisture to use for growing a crop in the following year. Agriculture represents 70% of freshwater use worldwide.
Processing, distribution, and marketing
Main article: Food processing
Main article: Agricultural marketing
In the United States, food costs attributed to processing, distribution, and marketing have risen while the costs attributed to farming have declined. This is related to the greater efficiency of farming, combined with the increased level of value addition (e.g. more highly processed products) provided by the supply chain. From 1960 to 1980 the farm share was around 40%, but by 1990 it had declined to 30% and by 1998, 22.2%. Market concentration has increased in the sector as well, with the top 20 food manufacturers accounting for half the food-processing value in 1995, over double that produced in 1954. As of 2000 the top six US supermarket groups had 50% of sales compared to 32% in 1992. Although the total effect of the increased market concentration is likely increased efficiency, the changes redistribute economic surplus from producers (farmers) and consumers, and may have negative implications for rural communities.
Crop alteration and biotechnology
Main article: Plant breeding
Tractor and Chaser bin.
Crop alteration has been practiced by humankind for thousands of years, since the beginning of civilization. Altering crops through breeding practices changes the genetic make-up of a plant to develop crops with more beneficial characteristics for humans, for example, larger fruits or seeds, drought-tolerance, or resistance to pests. Significant advances in plant breeding ensued after the work of geneticist Gregor Mendel. His work on dominant and recessive alleles gave plant breeders a better understanding of genetics and brought great insights to the techniques utilized by plant breeders. Crop breeding includes techniques such as plant selection with desirable traits, self-pollination and cross-pollination, and molecular techniques that genetically modify the organism. Domestication of plants has, over the centuries increased yield, improved disease resistance and drought tolerance, eased harvest and improved the taste and nutritional value of crop plants. Careful selection and breeding have had enormous effects on the characteristics of crop plants. Plant selection and breeding in the 1920s and 1930s improved pasture (grasses and clover) in New Zealand. Extensive X-ray an ultraviolet induced mutagenesis efforts (i.e. primitive genetic engineering) during the 1950s produced the modern commercial varieties of grains such as wheat, corn (maize) and barley.
The green revolution popularized the use of conventional hybridization to increase yield many folds by creating "high-yielding varieties". For example, average yields of corn (maize) in the USA have increased from around 2.5 tons per hectare (t/ha) (40 bushels per acre) in 1900 to about 9.4 t/ha (150 bushels per acre) in 2001. Similarly, worldwide average wheat yields have increased from less than 1 t/ha in 1900 to more than 2.5 t/ha in 1990. South American average wheat yields are around 2 t/ha, African under 1 t/ha, Egypt and Arabia up to 3.5 to 4 t/ha with irrigation. In contrast, the average wheat yield in countries such as France is over 8 t/ha. Variations in yields are due mainly to variation in climate, genetics, and the level of intensive farming techniques (use of fertilizers, chemical pest control, growth control to avoid lodging).
Genetic Engineering
Main article: Genetic Engineering
Genetically Modified Organisms (GMO) are organisms whose genetic material has been altered by genetic engineering techniques generally known as recombinant DNA technology. Genetic engineering has expanded the genes available to breeders to utilize in creating desired germlines for new crops. After mechanical tomato-harvesters were developed in the early 1960s, agricultural scientists genetically modified tomatoes to be more resistant to mechanical handling. More recently, genetic engineering is being employed in various parts of the world, to create crops with other beneficial traits.
[edit] Herbicide-tolerant GMO Crops
Roundup Ready seed has a herbicide resistant gene implanted into its genome that allows the plants to tolerate exposure to glyphosate. Roundup is a trade name for a glyphosate-based product, which is a systemic, nonselective herbicide used to kill weeds. Roundup Ready seeds allow the farmer to grow a crop that can be sprayed with glyphosate to control weeds without harming the resistant crop. Herbicide-tolerant crops are used by farmers worldwide. Today, 92% of soybean acreage in the US is planted with genetically modified herbicide-tolerant plants.[66] With the increasing use of herbicide-tolerant crops, comes an increase in the use of glyphosate-based herbicide sprays. In some areas glyphosate resistant weeds have developed, causing farmers to switch to other herbicides.[67][68] Some studies also link widespread glyphosate usage to iron deficiencies in some crops, which is both a crop production and a nutritional quality concern, with potential economic and health implications.
Insect-Resistant GMO Crops
Other GMO crops used by growers include insect-resistant crops, which have a gene from the soil bacterium Bacillus thuringiensis (Bt), which produces a toxin specific to insects. These crops protect plants from damage by insects; one such crop is Starlink. Another is cotton, which accounts for 63% of US cotton acreage.
Some believe that similar or better pest-resistance traits can be acquired through traditional breeding practices, and resistance to various pests can be gained through hybridization or cross-pollination with wild species. In some cases, wild species are the primary source of resistance traits; some tomato cultivars that have gained resistance to at least nineteen diseases did so through crossing with wild populations of tomatoes.
Costs and Benefits of GMOs
Genetic engineers may someday develop transgenic plants which would allow for irrigation, drainage, conservation, sanitary engineering, and maintaining or increasing yields while requiring fewer fossil fuel derived inputs than conventional crops. Such developments would be particularly important in areas which are normally arid and rely upon constant irrigation, and on large scale farms. However, genetic engineering of plants has proven to be controversial. Many issues surrounding food security and environmental impacts have risen regarding GMO practices. For example, GMOs are questioned by some ecologists and economists concerned with GMO practices such as terminator seeds, which is a genetic modification that creates sterile seeds. Terminator seeds are currently under strong international opposition and face continual efforts of global bans. Another controversial issue is the patent protection given to companies that develop new types of seed using genetic engineering. Since companies have intellectual ownership of their seeds, they have the power to dictate terms and conditions of their patented product. Currently, ten seed companies control over two-thirds of the global seed sales. Vandana Shiva argues that these companies are guilty of biopiracy by patenting life and exploiting organisms for profit Farmers using patented seed are restricted from saving seed for subsequent plantings, which forces farmers to buy new seed every year. Since seed saving is a traditional practice for many farmers in both developing and developed countries, GMO seeds legally bind farmers to change their seed saving practices to buying new seed every year.
Locally adapted seeds are an essential hertitage that has the potential to be lost with current hybridized crops and GMOs. Locally adapted seeds, also called land races or crop eco-types, are important because they have adapted over time to the specific microclimates, soils, other environmental conditions, field designs, and ethnic preference indigenous to the exact area of cultivation. Introducing GMOs and hybridized commercial seed to an area brings the risk of cross-pollination with local land races Therefore, GMOs pose a threat to the sustainability of land races and the ethnic heritage of cultures. Once seed contains transgenic material, it becomes subject to the conditions of the seed company that owns the patent of the transgenic material.
There is also concern that GMOs will cross-pollinate with wild species and permanently alter native populations’ genetic integrity; there are already identified populations of wild plants with transgenic genes. GMO gene flow to related weed species is a concern, as well as cross-pollination with non-transgenic crops. Since many GMO crops are harvested for their seed, such as rapeseed, seed spillage in is problematic for volunteer plants in rotated fields, as well as seed-spillage during transportation.
Food safety and labeling
Food security issues also coincide with food safety and food labeling concerns. Currently a global treaty, the BioSafety Protocol, regulates the trade of GMOs. The EU currently requires all GMO foods to be labeled, whereas the US does not require transparent labeling of GMO foods. Since there are still questions regarding the safety and risks associated with GMO foods, some believe the public should have the freedom to choose and know what they are eating and require all GMO products to be labeled.
Environmental impact
Main article: Environmental issues with agriculture
Agriculture imposes external costs upon society through pesticides, nutrient runoff, excessive water usage, and assorted other problems. A 2000 assessment of agriculture in the UK determined total external costs for 1996 of £2,343 million, or £208 per hectare.[81] A 2005 analysis of these costs in the USA concluded that cropland imposes approximately $5 to 16 billion ($30 to $96 per hectare), while livestock production imposes $714 million.[82] Both studies concluded that more should be done to internalize external costs, and neither included subsidies in their analysis, but noted that subsidies also influence the cost of agriculture to society. Both focused on purely fiscal impacts. The 2000 review included reported pesticide poisonings but did not include speculative chronic effects of pesticides, and the 2004 review relied on a 1992 estimate of the total impact of pesticides.
A key player who is credited to saving billions of lives because of his revolutionary work in developing new agricultural techniques is Norman Borlaug. His transformative work brought high-yield crop varieties to developing countries and earned him an unofficial title as the father of the Green Revolution.
Livestock issues
A senior UN official and co-author of a UN report detailing this problem, Henning Steinfeld, said "Livestock are one of the most significant contributors to today's most serious environmental problems".[83] Livestock production occupies 70% of all land used for agriculture, or 30% of the land surface of the planet. It is one of the largest sources of greenhouse gases, responsible for 18% of the world's greenhouse gas emissions as measured in CO2 equivalents. By comparison, all transportation emits 13.5% of the CO2. It produces 65% of human-related nitrous oxide (which has 296 times the global warming potential of CO2,) and 37% of all human-induced methane (which is 23 times as warming as CO2. It also generates 64% of the ammonia, which contributes to acid rain and acidification of ecosystems. Livestock expansion is cited as a key factor driving deforestation, in the Amazon basin 70% of previously forested area is now occupied by pastures and the remainder used for feedcrops.[84] Through deforestation and land degradation, livestock is also driving reductions in biodiversity.
Land transformation and degradation
Land transformation, the use of land to yield goods and services, is the most substantial way humans alter the Earth's ecosystems, and is considered the driving force in the loss of biodiversity. Estimates of the amount of land transformed by humans vary from 39–50%. Land degradation, the long-term decline in ecosystem function and productivity, is estimated to be occurring on 24% of land worldwide, with cropland overrepresented.[86] The UN-FAO report cites land management as the driving factor behind degradation and reports that 1.5 billion people rely upon the degrading land. Degradation can be deforestation, desertification, soil erosion, mineral depletion, or chemical degradation (acidification and salinization).
Eutrophication
Eutrophication, excessive nutrients in aquatic ecosystems resulting in algal blooms and anoxia, leads to fish kills, loss of biodiversity, and renders water unfit for drinking and other industrial uses. Excessive fertilization and manure application to cropland, as well as high livestock stocking densities cause nutrient (mainly nitrogen and phosphorus) runoff and leaching from agricultural land. These nutrients are major nonpoint pollutants contributing to eutrophication of aquatic ecosystems.
Pesticides
Pesticide use has increased since 1950 to 2.5 million tons annually worldwide, yet crop loss from pests has remained relatively constant. The World Health Organization estimated in 1992 that 3 million pesticide poisonings occur annually, causing 220,000 deaths.[89] Pesticides select for pesticide resistance in the pest population, leading to a condition termed the 'pesticide treadmill' in which pest resistance warrants the development of a new pesticide.An alternative argument is that the way to 'save the environment' and prevent famine is by using pesticides and intensive high yield farming, a view exemplified by a quote heading the Center for Global Food Issues website: 'Growing more per acre leaves more land for nature'. However, critics argue that a trade-off between the environment and a need for food is not inevitable,and that pesticides simply replace good agronomic practices such as crop rotation.
Climate Change
Climate change has the potential to affect agriculture through changes in temperature, rainfall (timing and quantity), CO2, solar radiation and the interaction of these elements. Agriculture can both mitigate or worsen global warming. Some of the increase in CO2 in the atmosphere comes from the decomposition of organic matter in the soil, and much of the methane emitted into the atmosphere is caused by the decomposition of organic matter in wet soils such as rice paddies.[95] Further, wet or anaerobic soils also lose nitrogen through denitrification, releasing the greenhouse gas nitric oxide. Changes in management can reduce the release of these greenhouse gases, and soil can further be used to sequester some of the CO2 in the atmosphere.
Distortions in modern global agriculture
See also: Agricultural subsidy
Differences in economic development, population density and culture mean that the farmers of the world operate under very different conditions.
A US cotton farmer may receive US$230 in government subsidies per acre planted (in 2003), while farmers in Mali and other third-world countries do without. When prices decline, the heavily subsidised US farmer is not forced to reduce his output, making it difficult for cotton prices to rebound, but his Mali counterpart may go broke in the meantime.
A livestock farmer in South Korea can calculate with a (highly subsidized) sales price of US$1300 for a calf produced. A South American Mercosur country rancher calculates with a calf's sales price of US$120–200 (both 2008 figures). With the former, scarcity and high cost of land is compensated with public subsidies, the latter compensates absence of subsidies with economics of scale and low cost of land.
In the Peoples Republic of China, a rural household's productive asset may be one hectare of farmland.In Brazil, Paraguay and other countries where local legislature allows such purchases, international investors buy thousands of hectares of farmland or raw land at prices of a few hundred US$ per hectare.
Energy and agriculture
Since the 1940s, agricultural productivity has increased dramatically, due largely to the increased use of energy-intensive mechanization, fertilizers and pesticides. The vast majority of this energy input comes from fossil fuel sources. Between 1950 and 1984, the Green Revolution transformed agriculture around the globe, with world grain production increasing by 250% as world population doubled. Modern agriculture's heavy reliance on petrochemicals and mechanization has raised concerns that oil shortages could increase costs and reduce agricultural output, causing food shortages.
Agriculture and food system share (%) of total energy
consumption by three industrialized nations
Country Year Agriculture
(direct & indirect) Food
system
United Kingdom 2005 1.9 11
United States of America 1996 2.1 10
Sweden 2000 2.5 13
Modern or industrialized agriculture is dependent on fossil fuels in two fundamental ways: 1) direct consumption on the farm and 2) indirect consumption to manufacture inputs used on the farm. Direct consumption includes the use of lubricants and fuels to operate farm vehicles and machinery; and use of gas, liquid propane, and electricity to power dryers, pumps, lights, heaters, and coolers. American farms directly consumed about 1.2 exajoules (1.1 quadrillion BTU) in 2002, or just over 1 percent of the nation's total energy.Indirect consumption is mainly oil and natural gas used to manufacture fertilizers and pesticides, which accounted for 0.6 exajoules (0.6 quadrillion BTU) in 2002.The energy used to manufacture farm machinery is also a form of indirect agricultural energy consumption, but it is not included in USDA estimates of U.S. agricultural energy use. Together, direct and indirect consumption by U.S. farms accounts for about 2 percent of the nation's energy use. Direct and indirect energy consumption by U.S. farms peaked in 1979, and has gradually declined over the past 30 years.
Food systems encompass not just agricultural production, but also off-farm processing, packaging, transporting, marketing, consumption, and disposal of food and food-related items. Agriculture accounts for approximately one-fifth of food system energy use in the United States.
Oil shortages could impact this food supply. Some farmers using modern organic-farming methods have reported yields as high as those available from conventional farming without the use of synthetic fertilizers and pesticides. However, the reconditioning of soil to restore nutrients lost during the use of monoculture agriculture techniques made possible by petroleum-based technology takes time.
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In 2007, higher incentives for farmers to grow non-food biofuel cropscombined with other factors (such as over-development of former farm lands, rising transportation costs, climate change, growing consumer demand in China and India, and population growth) to cause food shortages in Asia, the Middle East, Africa, and Mexico, as well as rising food prices around the globe.As of December 2007, 37 countries faced food crises, and 20 had imposed some sort of food-price controls. Some of these shortages resulted in food riots and even deadly stampedes.
The biggest fossil fuel input to agriculture is the use of natural gas as a hydrogen source for the Haber-Bosch fertilizer-creation process.Natural gas is used because it is the cheapest currently available source of hydrogen. When oil production becomes so scarce that natural gas is used as a partial stopgap replacement, and hydrogen use in transportation increases, natural gas will become much more expensive. If the Haber Process is unable to be commercialized using renewable energy (such as by electrolysis) or if other sources of hydrogen are not available to replace the Haber Process, in amounts sufficient to supply transportation and agricultural needs, this major source of fertilizer would either become extremely expensive or unavailable. This would either cause food shortages or dramatic rises in food prices.
Mitigation of effects of petroleum shortages
One effect oil shortages could have on agriculture is a full return to organic agriculture. In light of peak-oil concerns, organic methods are more sustainable than contemporary practices because they use no petroleum-based pesticides, herbicides, or fertilizers. Some farmers using modern organic-farming methods have reported yields as high as those available from conventional farming.Organic farming may however be more labor-intensive and would require a shift of the workforce from urban to rural areas.
It has been suggested that rural communities might obtain fuel from the biochar and synfuel process, which uses agricultural waste to provide charcoal fertilizer, some fuel and food, instead of the normal food vs fuel debate. As the synfuel would be used on-site, the process would be more efficient and might just provide enough fuel for a new organic-agriculture fusion.
It has been suggested that some transgenic plants may some day be developed which would allow for maintaining or increasing yields while requiring fewer fossil-fuel-derived inputs than conventional crops. The possibility of success of these programs is questioned by ecologists and economists concerned with unsustainable GMO practices such as terminator seeds, and a January 2008 report shows that GMO practices "fail to deliver environmental, social and economic benefits." While there has been some research on sustainability using GMO crops, at least one hyped and prominent multi-year attempt by Monsanto Company has been unsuccessful, though during the same period traditional breeding techniques yielded a more sustainable variety of the same crop.[128] Additionally, a survey by the bio-tech industry of subsistence farmers in Africa to discover what GMO research would most benefit sustainable agriculture only identified non-transgenic issues as areas needing to be addressed. Nevertheless, some governments in Africa continue to view investments in new transgenic technologies as an essential component of efforts to improve sustainability.
Electrical energy efficiency on farms
Main article: Electrical energy efficiency on United States farms
Policy
Main article: Agricultural policy
Agricultural policy focuses on the goals and methods of agricultural production. At the policy level, common goals of agriculture include:
* Conservation
* Economic stability
* Environmental impact
* Food quality: Ensuring that the food supply is of a consistent and known quality.
* Food safety: Ensuring that the food supply is free of contamination.
* Food security: Ensuring that the food supply meets the population's needs.
* Poverty Reduction
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