Substantially transforming structural policy alone will be difficult considering various social, historical, cultural and geographical conditions. This category comprises large-scale agriculture like that in the United States. It is difficult to perform as mixed agriculture, but, because it requires energy obtained from biomass, it can produce grains on the most fertile land if high-yield technologies are implemented. On low-fertility marginal land, the zoning of food and bioenergy will progress as types of vegetation are planted that produce large quantities of biomass and do not require fertilization.