I am certainly not an expert but, because I live in Minnesota, I hear things. The current farm subsidy rules seem to discourage farming diversity by only giving subsidies for certain crops to certain areas of the country. For instance a farm subsidy for soybeans could only be had in the Midwest while a subsidy for fruit can only be had in Florida or California.
If we are to reduce our carbon emissions and, promote biodiversity, why would we not encourage a full range of crops in any area of the country where they can be grown. I worry about a disease attacking the fruit growers in the central valley of California, or bad weather in Minnesota creating great imbalances in our food resources. Why create a system where we have to ship a great percentage of everything we eat?
If we cannot encourage diversity in our agricultural system then at least let us not discourage it by only subsidizing certain crops in certain regions. I suggest that if we are to give subsidies we find a way to subsidize effective land usage rather than crop monopolies for certain regions.