Most agricultural policy or subsidy has purposes other than profit. A very strong evidence for this is that huge amounts of excess food are often disposed of very cheaply, e.g. by export to developing nations as foreign aid[?], or as part of local food bank or food stamp[?] programs. Agricultural economics[?] studies these 'other purposes' to see what insights they provide into economics, and to help set such policies in the context of a larger economy in which most activity is not agricultural.
A key stated goal of agricultural subsidies is food self-suffiency[?] to prevent the shock of rapid price rises in essential groceries. To submit the entire food supply of a nation to the whims of commodity markets is considered a poor idea. Another goal is to improve biosecurity by minimizing the amount of overall organic material imported, e.g. recent United States Food and Drug Administration rules applied to foreign exporters of food to the US.
Another stated goal is to encourage organic farming and precision agriculture, often combined in the idea of the "garden economy[?]". When the USSR was unable to feed itself it was often observed that over half of the local food supply was coming from small private gardens growing native varieties with organic means, despite the fact that the government had done everything in its power to discourage such small-scale organic entrepreneurs.
However, many political observers argue that the true purpose of agricultural subsidies is in the end to protect farmers so that they will continue to vote for the politicians that vote for these subsidies. Many economists regard farm subsidies as objectionable because they cause the economy to be less efficient than they would otherwise be, the primary beneficiaries of these subsidies are large corporations who do not deserve much sympathy, and that these subsidies prevent farmers in the third world from competing in local and export markets, thereby creating third world poverty.
Most green economists argue that such measures ought to be strongly encouraged, and so consider agricultural policy that exempts small gardens and greenhouses from regulations to be desirable, especially if produce is consumed locally. They argue for tax, tariff and trade rules to exempt such production for local use, especially family farm or farm co-op[?] production, and strongly deny that agricultural and industrial policy should be linked, or should be subject to the same law. One rationale is that local production of organic produce by families in their own gardens for their own consumption is not taxed or regulated, and that little or no use of the energy-and-land-intensive transport system, or energy-and-labor intensive regulation system is required for these same people to sell the same product to neighbors.
Rules for rural land ownership typically affect both agricultural policy and family farms. Some economists, e.g. de Soto[?], Joseph Stiglitz, argue that comprehensive land reform is more likely than any amount of tax, tariff and trade system, and more likely than any specifically agricultural policy, to improve life in developing nations.
Immigration policy in some developed nations has exceptions specifically to enable agricultural policy, e.g. migrant farm workers in Canada and the US.
The United States has almost ended farm subsidies several times, most recently with the enactment of the "Freedom to Farm" act, which was intended to provide diminishing payments to farmers over a period of years in lieu of price supports and production subsidies. It was supplanted in 2002 by new legislation that contained direct subsidies and countercyclical payments designed to limit the effects of poor prices and yields in bad years. Grain crops are most heavily subsidized.
Another major U.S. subsidy program is the "conservation reserve program" (CRP) which pays producers to take marginal land out of production. In addition, there are major regulatory frameworks that have environmental, safety, and food quality goals.
Other, more subtle measures enacted by the states and local governments affect farming, such as zoning and tax policy.
Since imported/exported agricultural produce is mostly traded and entirely priced on commodity markets, but presents special biosafety and biosecurity risks, there is a strong bias in all agricultural markets to compromise safety to achieve low prices.
Two initiatives in global trade tend to focus clearly on changing nations' agricultural policy:
Plans to reduce or remove agricultural subsidies have led often to violent confrontations even in developed nations, e.g. very often in France. The issue is very politically loaded and there are strong constituencies both for and against agricultural reforms.