Organic farming is any system of agriculture in which crops, food animals, or both are grown using natural methods of maintaining fertility of the soil, Page 3158 | Top of Articleincluding methods of pest control other than synthetic pesticides and fertilizers. Compared with industrial agricultural systems, which intensively use manufactured fertilizers and pesticides, smaller environmental costs and damages are associated with organic systems. However, yields tend to be smaller in organic agriculture than are obtained using more intensively managed systems. Scientific tracking of the results of organic agriculture over the last several decades has shown that that compared with more industrialized forms of agriculture, organic farming is better able to retain soil, ecological integrity, biodiversity, and energy and material resources. It is also, at this time, more labor-intensive and therefore more expensive, at least in industrialized countries.
Organic methods of maintaining soil tilth and fertility
Soil fertility is a function of two major characteristics: the tilth of the soil, and the ability of the soil to supply essential nutrients to crop plants.
Tilth refers to the physical structure of soil, and is strongly influenced by the concentration of humified organic matter. In soils with good tilth the ability to hold water is great, so that excessively rapid drainage is avoided and rainwater can be used more effectively by growing plants. The organic matter also helps to bind nutrients, thereby preventing them from being lost by leaching, and releasing them slowly for more efficient uptake by growing plants. In addition, soils with good tilth have their sand-sized and smaller inorganic particles loosely aggregated into lumpy structures, which improves soil aeration and eases the growth and penetration of plant roots.
Typically, soil tilth becomes badly degraded in conventional, intensively managed agricultural systems. This happens because soil organic matter is progressively lost through plowing and decomposition, while inputs with plant debris are relatively small. Compaction by heavy vehicles also helps to degrade soil tilth. In contrast, a major goal of organic agriculture is to maintain or increase the concentration of organic matter in the soil (using methods that are described below, in regard to nutrients).
Plants require more than 20 nutrients for proper growth. Some of these nutrients are obtained primarily from the soil, especially compounds of nitrogen, phosphorus, potassium, calcium, magnesium, and Page 3159 | Top of Articlesulfur. These nutrients are primarily taken up by plants as inorganic compounds. For example, nitrogen is mostly assimilated from soil as nitrate or ammonium, while phosphorus is taken up as phosphate. In natural ecosystems, these inorganic compounds are steadily recycled by microorganisms from dead organic matter such as plant litter. The microorganisms have the ability to metabolize complex organic forms of nutrients and convert them to simple, inorganic forms, such as the ones just listed. As they perform this function, the microorganisms gain access to the fixed energy and nutrients of dead biomass that they require for their own growth and reproduction. Therefore, soil fertility in natural ecosystems is largely associated with organic matter, from which inorganic nutrients are slowly released from complex, organic forms. These are then efficiently taken up by plants, so that little of these precious nutrients is lost to ground or surface waters or to the atmosphere.
However, in intensively managed agricultural systems, inorganic nutrients are usually added directly, in the form of manufactured fertilizers of various sorts. Synthetic inorganic fertilizers are manufactured industrially from raw materials. For example, rock phosphate mined in Florida or elsewhere is manufactured into super- and triple-superphosphate fertilizers. Inorganic nitrogen fertilizers such as urea and ammonium nitrate are manufactured by combining atmospheric dinitrogen (or nitrogen gas) with hydrogen obtained from methane (or natural gas). Inorganic potassium is obtained from potash, a mined material rich in that chemical, while calcium and magnesium are obtained from limestone (calcium carbonate) or dolomite (calcium, magnesium carbonate). Sulfur fertilizers are manufactured from elemental sulfur or sulfuric acid obtained from sour natural gas or from air-pollution control at metal smelters. The manufacturing of all of these fertilizers has large costs in terms of energy and the depletion of nonrenewable material resources.
Often, the rates of fertilization in intensively managed agriculture are intended to satiate the needs of crop plants for these chemicals, so their productivity will not be limited by nutrient availability. However, excessive rates of fertilization have important environmental costs. These include: the contamination of ground water with nitrate; eutrophication of surface waters caused by nutrient inputs (especially phosphate); acidification of soil because of the nitrification of ammonium to nitrate; large emissions of nitrous oxide and other nitrogen gases to the atmosphere, with implications for acid rain and Earth's greenhouse effect; and the need to use herbicides to control the weeds that flourish under artificially nutrient-rich conditions.
In contrast, organic methods of maintaining site fertility focus on soil organic matter. Much action is expended on maintaining or increasing the amount of organic matter in the soil, because this is the reservoir from which inorganic nutrients are slowly made available to growing crop plants. Organic matter is also critical to soil tilth, as was previously described. Organic farmers add nutrient-containing organic matter to their soils in three major ways.
First, as dung and urine of animals, which contains both organic matter and large concentrations of nutrients. However, care must be taken to avoid the contamination of surface and ground waters with pathogenic bacteria. This method of organic fertilization also causes local air pollution with ammonia and distasteful smells.
Second, as green manure, which is growing or recently harvested plant material that is directly incorporated into the soil, usually by plowing. The most fertile green manures are the biomass of plants in the legume family, such as alfalfa or clovers. This is because legumes have a symbiosis with a bacterium that can fix atmospheric dinitrogen (N 2) into biologically useful nitrogen. Consequently, legume-derived green manure is a commonly used organic means of fertilization with nitrogen.
Finally as compost, or partially decomposed and humified organic material. Composting is an aerobic process by which microorganisms aided by soil animals break down and metabolize organic material, eventually forming complex, large molecular-weight materials known as humic substances. These are resistant to further decay, and are very useful as a soil conditioner and to a lesser degree as an organic fertilizer.
It is important to understand that growing plants take up the same, simple, inorganic forms of nutrients from soil (for example, nitrate, ammonium, or phosphate), regardless of whether these are supplied by organic matter or manufactured fertilizer. The important difference between fertilization using organic or synthetic materials is in the role of ecological processes versus manufacturing ones. Organic methods rely more heavily on renewable sources of energy and materials, rather than on non-renewable materials and fossil fuels. Overall, the longer-term environmental implications of maintaining soil tilth and fertility using organic methods are much softer than those associated with conventional, intensive agriculture.
Organic methods of managing pests
In agriculture, pests are any organisms that significantly interfere with the productivity of crop plants or animals. This can occur when insects eat foliage or stored produce, when bacteria or fungi cause plant or animal diseases, or when weeds interfere excessively with the growth of crop plants. In conventional agriculture, these negative influences of pests are usually managed using various types of pesticides, such as insecticides, herbicides, and fungicides. On the shorter term, these methods can be effective in reducing the influence of pests on agricultural productivity. However, important environmental damages can be associated with the use of pesticides.
Organic farmers do not use synthetic, manufactured pesticides to manage their pest problems. Rather, reliance is placed on other methods of pest management, the most important of which are:
- The use of varieties of crop species that are resistant to pests and diseases. If the crop species has genetically based variations of tolerance to the pest or disease, then resistant varieties can be developed using standard breeding techniques;
- Attacking the pest biologically, by introducing or enhancing populations of its natural predators, parasites, or diseases;
- Changing other ecological conditions to make the habitat less suitable for the pest. Depending on the pest, this may be possible by growing plants in mixed culture rather than in monoculture; by rotating crops or by using a fallow period so that pest populations do not build up in particular fields; by managing the overwintering microhabitat of certain pests; by using mechanical methods of weed control such as handpulling or shallow plowing; and by other means. Obviously, use of these techniques requires knowledge of the ecological requirements and vulnerabilities of important pest species.
- Undertaking careful monitoring of the abundance of pests, so that specific control strategies are used only when required. Note that this may include the use of certain pesticides, but these must be based on a natural product. For example, an insecticide based on the bacterium Bacillus thuringiensis (or B.t.) may be acceptable, as may one based on pyrethrum, a chemical extracted from several species of plants related to the daisy. However, synthetic analogues of these, such as genetically engineered B.t. or synthesized pyrethroids are not considered acceptable in organic agriculture.
Note that many of these pest-control practices are important components of a system known as integrated pest management. However, in that system pesticides are often used as a last resort, when other methods do not work effectively enough. In organic agriculture, pesticides are not used (other than the “natural” ones just referred to).
In addition, organic farmers, and the consumers of the goods that they produce, must be relatively tolerant of some of the damages and lower yields that pests cause. Consumers, for example, may have to be satisfied with apples that have some degree of blemishing associated with scab, a fungal-caused problem that does not affect the nutritional quality or safety of the apple, but has become associated with poor aesthetics. In conventional agriculture, this cosmetic damage is managed through the use of pesticides, in order to supply consumers with apples of an aesthetic quality that they have become conditioned to expect.
Use of antibiotics and growth regulating hormones
In some types of intensive culture of agricultural livestock, animals are kept together under very crowded conditions, often inside large buildings in a poorly ventilated and smelly environment, and often continuously exposed to their manure and urine. Under these sorts of conditions animals are highly vulnerable to developing infections of various sorts, which ultimately cause reductions of growth, and may result in their death. To manage this problem, intensive agriculture typically relies on antibiotics. These may be given to animals when they are actually sick, or they may be added continuously to their food as a prophylactic (or preventive) treatment. Ultimately, humans are exposed to small residues of antibiotics in products of these animals that they consume. It has not been scientifically established that this exposure poses an unacceptable risk to humans, potentially occurring, for example, through the evolution of resistant varieties of antibiotic-resistant pathogens. Nevertheless, there is controversy about the antibiotic contamination of foodstuffs from intensive agriculture.
Organic farmers might also use antibiotics to treat an infection in a particular sick animal, but they do not continuously add those chemicals to food that is fed to livestock. In addition, many organic farmers attempt to keep their animals under more open and sanitary conditions than are often conventionally used to intensively rear livestock under dense, industrial Page 3161 | Top of Articleconditions. Animals that are relatively free of the stresses of crowding and constant exposure to manure are more resistant to diseases, and have less of a need of antibiotics.
In addition, some industrial systems of raising livestock use synthetic growth hormones, such as bovine growth hormone, to increase the productivity of their animals, or of animal products such as milk. Inevitably, these hormones persist in a trace contamination in the animal products that humans consume. Although no significant risk to humans has been convincingly demonstrated from these exposures, there is controversy about the potential effects. Organic farmers do not use synthetic growth hormones to enhance the productivity of their livestock.
Organic and non-organic foods
Many people believe that organically grown foods are safer or more nutritious than the same foods grown using conventional agricultural systems. In large part, these beliefs are influenced by the occurrence of trace contamination of non-organic foods with pesticides, antibiotics, and growth hormones. Although this topic is highly controversial, scientific studies have not convincingly demonstrated that organically grown foods are indeed safer or more nutritious than conventional agricultural produce. There have been some notable exceptions, such as the spread of bovine encephalopathy (mad cow disease) through beef, which was only made possible by the industrial-agricultural practice of grinding up dead livestock to feed to livestock. Organically grown beef cannot spread mad cow disease. Moreover, many persons who buy organic food are not operating under the (possible) illusion that they are primarily protecting their personal health by eating organic foods; they are concerned that their relationship to the food-production system, and to the Earth on which that system depends, be one that they can contemplate with satisfaction rather than dismay. In this regard, there is no scientific doubt that organic agriculture results in lessened soil loss and other impacts on the natural world as compared to industrial agriculture. Organic agricultural systems use less of non-renewable resources of energy and materials, keep the agricultural ecosystem in better health, and enhance the sustainability of the agriculture.
The popularity of organic culture
The environmental damage and resource use associated with organic agriculture are much less than those of conventional agricultural systems. However, yields tend to be smaller, and the organically grown produce is often relatively expensive to the consumer. Overall, the balance of these two considerations suggests that society receives a positive net benefit from the use of organic agricultural systems.
Organic agricultural systems will not become more widely adopted unless a number of socioeconomic conditions change. First, larger numbers of consumers will have to be willing to pay the somewhat higher costs of organically grown food, and they will have to modify some of their perceptions about the aesthetic qualities of certain foods (e.g., apple blemishes). This appears to have been happening in some industrialized countries; in the United States, for example, sales of organic food increased by over 16 percent in 2005 alone, to a total of $13.8 billion in consumer sales. By 2012, organic food sales had doubled to $27 billion. Second, vested agricultural interests in big business, government, and universities will have to become more sympathetic to the goals and softer environmental effects of organic agriculture. These institutions will have to support more research into organic agriculture, and promote the use of those systems. Lastly, it will be necessary that the practitioners of intensive agricultural systems be made to deal more directly and sensibly with the environmental damage associated with their activities, especially the use of manufactured pesticides and fertilizers. As with many other industries, agriculture is presently allowed to “externalize” environmental damages that Page 3162 | Top of Articleit causes—that is, to make profits in the present while letting other people, downwind or downstream or in the future, suffer the costs.
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Reed, Matthew. Rebels for the Soil: The Rise of the Global Organic Food and Farming Movement. New York: Routledge, 2010.
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Taji, Acram, and John Reganold, eds. Organic Agriculture: A Global Perspective. Collingwood, Canada: CSIRO Publishing, 2006.
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