 Such rents are according to Marx, part of the total cost-structure of capitalist production, and a component of the value of agricultural output.Suppose for example that the ruling world market price for quality wheat is about US$350 per metric tonne f.o.b.Even if two investors have the exactly same amount of capital to invest in wheat production, the economics of producing wheat at that price are going to be quite different, depending on the actual yields (the productivity) of the land they use.