At least back when I lived in a farm community, a lot of subsidies involved letting a percentage of the farmers fields lay fallow and being paid as if it were producing. Fallow fields prevent crop boom-and-bust cycles as well as resist salinization of the soil, soil erosion, promote the micro-biotic health of the soil, etcetcetc. Also, there have been many subsidies in the US historically (enacted after the dust bowl) for doing things like building what were called 'property line wind breaks'. IE- farmers planting certain types of trees like weeping willows along property line divisions. Terracing, also once received gov't support.

Historically, exactly these types of subsidies have been attacked by the right as 'paying the farmers to sit on their ass', and may not exist anymore. They were on their way out when I was a kid, if I recall, in favor of more of the 'minimum price' type subsidy. The restructuring in farm subsidies is one of the main reason you see the death of the family farm- it really is more of a myth now days. Agribiz with farms over a thousand acres or dairies with thousands of cows, pig farms with thousands of pigs packed onto 40 acre plots- these are the norm now days. Anyone who has lived out west can tell you what these do for the environment. You know when you are withing 10 miles of a pig factory.

With minimum price subsidy, the more you produce, the more subsidy and guaranteed profit you make. Do the math. The small guy can't stay in business.

Yeti

Anyway- yes- soil erosion is a problem... So too is salinization and aquifer depletion. Serious problems.