to conventional farming. In the developing world, on small organic farms, tools are normally constrained to hand tools and diesel powered water pumps. Standards Standards regulate production methods and in some cases final output for organic agriculture. Standards may be voluntary or legislated. As early as the 1970s private associations certified organic producers. In the 1980s, governments began to produce organic production guidelines. In the 1990s, a trend toward legislated standards began, most notably with the 1991 EU-Eco-regulation developed for European Union, which set standards for 12 countries, and a 1993 UK program. The EU's program was followed by a Japanese program in 2001, and in 2002 the U.S. created the National Organic Program (NOP). As of 2007 over 60 countries regulate organic farming (IFOAM 2007:11). In 2005 IFOAM created the Principles of Organic Agriculture, an international guideline for certification criteria. Typically the agencies accredit certification groups rather than individual farms. Production materials used for the creation of USDA Organic certified foods require the approval of a NOP accredited certifier. EU-organic production-regulation on "organic" food labels define "organic" primarily in terms of whether "natural" or "artificial" substances were allowed as inputs in the food production process. Composting Using manure as a fertilizer risks contaminating food with animal gut bacteria, including pathogenic strains of E. coli that have caused fatal poisoning from eating organic food. To combat this risk, USDA organic standards require that manure must be sterilized through high temperature thermophilic composting. If raw animal manure is used, 120 days must pass before the crop is harvested if the final product comes into direct contact with the soil. For products that do not directly contact soil, 90 days must pass prior to harvest. In the US, the Organic Food Production Act of 1990 (OFPA,) as amended, specifies that a farm can not be certified as organic if the compost being used contains any synthetic ingredients. The OFPA singles out commercially blended fertilizers [composts] disallowing the use of any fertilizer [compost] that contains prohibited materials. Economics The economics of organic farming, a subfield of agricultural economics, encompasses the entire process and effects of organic farming in terms of human society, including social costs, opportunity costs, unintended consequences, information asymmetries, and economies of scale. Labour input, carbon and methane emissions, energy use, eutrophication, acidification, soil quality, effect on biodiversity, and overall land use vary considerably between individual farms and between crops, making