The document discusses economic theories of land use and agriculture from the 18th and 19th centuries. It summarizes Ricardo's law of rent from 1817, which states that rent is determined by the productivity of marginal land. It then discusses Von Thunen's model from 1826 of concentric crop zones around a central market based on transport costs, with more profitable crops closer to market. However, the model makes unrealistic assumptions and its predictions do not fully reflect today's dynamic agricultural system with changing technologies, markets, and farmer behaviors.