Radical, perhaps, though the US government had intervened to regulate surpluses through monetary policy before. As far as "un-American," I suppose that would depend on who you asked. The Supreme Court ruled that the Agricultural Adjustment Act, which contained many of the elements of the Domestic Allotment Act, unconstitutional, so I guess you could say they thought so.
The Domestic Allotment Act was an attempt to get around some of the stipulations made in that decision, as well as curbing abuses by landowners who often kept the checks their tenants received from the government for cutting production. Farm subsidies are regularly used to regulate supply of agricultural goods today.
I think it was an aggressive plan, but to be honest, the times probably called for it. What was needed was systematic reform in farming techniques as well as stablization of prices, and the Domestic Allotment Act as well as the conservation education legislation that went along with it may have been the only way to make it happen.