Two ways in which world war ii affected agriculture.

at the end of World War II, the farm economy once again faced the challenge of overproduction. Technological advances, such as the introduction of gasoline- and electric-powered machinery and the widespread use of pesticides and chemical fertilizers, meant production per hectare was higher than ever. To help consume surplus crops, which were depressing prices and costing taxpayers money, Congress in 1954 created a Food for Peace program that exported U.S. farm goods to needy countries. Policy-makers reasoned that food shipments could promote the economic growth of developing countries. Humanitarians saw the program as a way for America to share its abundance. 
In the 1960s, the government decided to use surplus food to feed America's own poor as well. During President Lyndon Johnson's War on Poverty, the government launched the federal Food Stamp program, giving low-income persons coupons that could be accepted as payment for food by grocery stores. Other programs using surplus goods, such as for school meals for needy children, followed. These food programs helped sustain urban support for farm subsidies for many years, and the programs remain an important form of public welfare -- for the poor and, in a sense, for farmers as well. 

But as farm production climbed higher and higher through the 1950s, 1960s, and 1970s, the cost of the government price support system rose dramatically. Politicians from non-farm states questioned the wisdom of encouraging farmers to produce more when there was already enough -- especially when surpluses were depressing prices and thereby requiring greater government assistance. 

The government tried a new tack. In 1973, U.S. farmers began receiving assistance in the form of federal "deficiency" payments, which were designed to work like the parity price system. To receive these payments, farmers had to remove some of their land from production, thereby helping to keep market prices up. A new Payment-in-Kind program, begun in the early 1980s with the goal of reducing costly government stocks of grains, rice, and cotton, and strengthening market prices, idled about 25 percent of cropland. 

Price supports and deficiency payments applied only to certain basic commodities such as grains, rice, and cotton. Many other producers were not subsidized. A few crops, such as lemons and oranges, were subject to overt marketing restrictions. Under so-called marketing orders, the amount of a crop that a grower could market as fresh was limited week by week. By restricting sales, such orders were intended to increase the prices that farmers received.