Organic foods are crops which have been produced without the use of synthetic pesticides and fertilizers, as well as genetic modification and certain preservation techniques such as food irradiation. The term also encompasses meat and other animal products (milk, cheese, honey) which have been produced without the use of antibiotics and growth hormones. Organic farming was pioneered by alternative medicine promoter Jerome Rodale (né Cohen) in the early part of the 20th century based on the idea that synthetic fertilizers and pesticides damaged the flavor and nutritional value of foods, and has become big business as consumers seek to reduce the environmental impact of food consumption and eliminate food safety issues such as pesticide persistence in food ingredients.
Governments usually set standards along these lines which must be adhered to in order for food to be legally sold as "organic." However, the scientific definition of an "organic" compound is any which contains carbon-hydrogen or carbon-carbon bonds, which applies to the overwhelming majority of carbon compounds as well as pretty much everything and anything of biological origin. In some countries, the regulatory role is taken on by non-governmental agencies. The Soil Association performs such a function in the UK In the United States, the USDA does have a certification program (which still allows pesticides), but so long as the food does not use the USDA Certified Organic logo, it can be sold as "organic" without any regulation.
Methods and benefits
Studies have found that organic farming can, if properly implemented, have environmental benefits over conventional farming. One of the earliest scientific verifications of organic productivity was demonstrated in a 22 year study by Cornell University, which found yields of organic to be equal or better and had the added benefit of omitting chemicals. 
Sustainability - the ability to leave the soil and growing environment fertile enough to grow more crops without major chemical or other intervention - is a major goal of many organic farmers; avoiding pesticides is another major issue, since many pesticides are also toxic to humans and other animal life. Common methods used to achieve these goals include:
- Crop rotation: the replanting of fields with different crops between seasons to repair damage done by a crop in the previous season; for example, swapping maize (a very soil-damaging crop requiring massive intervention by the farmer) with legumes such as soybeans or alfalfa (which live in symbiosis with "nitrogen-fixing" bacteria that can convert inert atmospheric nitrogen into bioavailable forms in the soil).
- Composting and "Natural" fertilizers: Instead of using inorganic salts and substances such as anhydrous ammonia, organic agriculture prefers fertilizers such as compost, manure, fermented fish guts (similar to the old New England native American practice of burying dead fish under maize plantings) and "green manure" (i.e. cover crops as mentioned above, plowed into the soil to decay and provide organic matter for the next growing season).
- Integrated pest management: a "defense in depth" method of dealing with pests, where blanket pesticide use is replaced with intercropping (planting of less-valuable, more-attractive barrier crops between plots of more valuable crops to attract pests), predators such as ladybugs and lacewings, pest traps, and more precisely targeted applications of biodegradable pesticides.
- Companion planting: Placing plants with common care needs in close proximity. The iconic "Three Sisters" combination used by North American Indians to raise beans, squash, and corn is one famous example; the beans use the corn stalk as support while enriching the soil with nitrogen-fixing bacteria, while the crawling squash plant provides a sort of mulch effect to protect the area from weeds. From there, entire books have been written on the subject.
Organically-raised meats are usually taken only from animals fed only plant matter (thus preventing the transmission of prion diseases and other illnesses carried in livestock feed containing animal by-products) and generally raised in less-stressful surroundings than the factory farms commonly used by meat producers.
Organic farming practices are generally not evidence-based, but rather arbitrarily decided upon based on a vague notion of what is "natural". As such, it is a form of appeal to nature. It may very well be that certain techniques used in organic farming have positive results, but other organic techniques have no impact or even negative results, but there's no way to tell without testing each technique (or specific technique-combination) on its own -- and that happens only rarely. Proponents and producers of organic food also engage in other pseudoscientific actions, such as scare campaigns against genetic engineering, food irradiation and other provably safe methods.
Part of the biggest issue with organic agriculture is that it cannot usually measure up in productivity to "Green Revolution" techniques of intensive agriculture. Organic food does sometimes taste better due to less emphasis on things such as fruit size and yield over quality; however, this is often at the cost of higher risk of insect damage and other cosmetic blemishes.
While organic agriculture has definite benefits to the producer, the consumer, and the environment, it is generally sold with vague, unsubstantiated claims that organic food is "safer," "healthier," or "more natural," leading organic food to become a fad diet and a form of nature woo. A more extreme form is biodynamic agriculture, which is broadly similar in its application to organic agriculture, but is based on the writings of Rudolf Steiner and his Anthroposophy religion, an offshoot of Theosophy; this particular species of woo (popular in the wine industry for some reason) is highly ritualistic, including aspects of homeopathy and possibly feng shui in its required techniques.
Organic food is not necessarily any healthier or more nutritious than conventional food. Indeed, a huge market exists for prepared organic foods that aren't drastically different from their conventional equivalents, and certainly aren't inherently a whole lot healthier for you just because they're certified organic (though they do tend to use no preservatives and less saturated fat).
A common misconception among dirty hippies is that buying organic means you are supporting local farmers and more sustainable agriculture. This is in fact false, as much of the organic food in your local supermarket is likely provided by big agribusiness corporations such as Dean, Cargill, and ConAgra. In this context, organic food preference shouldn't be confused with focused locavorism, which instead targets food grown locally, with organic preparation often a secondary aim.
- USDA publications on organic food
- Is Organic Food the Answer?
- Hoefkens, C., Verbeke, W., Aertsens, J., Mondelaers, K., Van Camp, J. (2009). The nutritional and toxicological value of organic vegetables : consumer perception versus scientific evidence. British Food Journal 111 (10), 1062‐1077. Full text
- Gillman, Jeff, The Truth about Organic Gardening. Portland, OR: Timber Press, 2008, ISBN 978-0881928624. Written by a horticulture professor at the University of Minnesota, this book is guardedly pro-organic, but warns the reader not to assume that "natural" means safe.
- Cornell 22 Year Study - Organic farming produces same corn and soybean yields as conventional farms, but consumes less energy and no pesticides, study finds- http://www.news.cornell.edu/stories/July05/organic.farm.vs.other.ssl.html
- Skeptoid dissects a lot of the myths surrounding organic food
- ↑ according to Wikipedia
- ↑ 
- ↑ Nutritional quality of organic foods: a systematic review
- ↑ Should I Buy Organic Foods? USDA
- ↑ Organic Processing Industry Structure, Philip H. Howard, Michigan State University
- ↑ Lockie et al. Eating Green: Motivations behind organic food consumption in Australia. Sociologia Ruralis, Volume 42, Issue 1, pages 23–40, January 2002
- ↑ The organic woo propaganda documentary Food Matters is a big offender in this area as it mixes legitimate criticisms of corporate influence over the food supply and food security with cancer woo like Gerson's quackery and raw foodism. See also the review by the Pike's Peak Skeptics Society.