Agriculture is not currently sustainable. Pesticides, much irrigation, artificial fertilizers and other farming techniques destroy the soil on which all civilization is dependent. The runoff of the pesticides and fertilizer contaminate fresh water and large parts of the oceans. The foods grown with these techniques lead to myriad health problems, while factory farming of livestock leads to super bacteria and unhealthy meat. Oil is required to run farm equipment and to move food thousands of miles.
The goal of a sustainable agricultural system would be to make each city region almost self-reliant in food, with farm belts around the major city or cities, and encouragement of urban gardens. These farm belts would be grow food without pesticides or artificial fertilizer. Such a system would require a much higher amount of labor, using intensive agricultural techniques, so that the main methods of farming would be closer to gardening than farming. If grains like wheat, rice and corn could be grown better in the Midwest, then we would want to switch to perennial varieties being pioneered by the Land Institute. Livestock should be raised according to the techniques being developed by people such as Joel Salatin, but fish aquaculture should be encouraged, and the revival of the oceans must become a top priority.
On average, it seems that 15% more labor is required for organic farming methods than for conventional approaches, according to Pimental et al from Cornell (p.11) . Organic food now constitutes about 4% of the food market . If, ideally, all food was grown organically, then we would theoretically require 15% more workers than the number of individuals currently employed, or about 270,000 more farmers.
There are more radical possibilities for the increase in employment that would result from a truly sustainable agricultural system. According to Richard Heinberg, up to 20% of the population could be required to grow everybody's food, up from 2% now, without the use of fossil fuels. Such a huge increase in agricultural work would require a truly world-class infrastructure in order to make transportation easy and efficient, as well as storage and tooling, and the Federal government would have to finance the bulk of the setup costs for such a system.