In the United States, for example, the government attempts to support bio-fuels resulted in price supports for corn grown for bio-fuel use. The consequence has been a glut of bio-fuel corn, and rising prices for feed corn as land is switched to bio-fuel corn. Rising prices for feed corn result in rising prices for beef in our supermarkets.
There is such a glut of price-supported agricultural products available (Canadian wheat, for example), that many countries divert their surpluses into foreign aid. And the result of dumping low cost wheat into the agricultural markets of Africa is to depress the price that local farmers can get for their own products. Hence local farmers in Africa are starving, and being driven off their farms. They simply can’t compete.