In the following treatment of these crops some phases of their production are discussed for each crop separately, while other phases are discussed for all or part of them combined. Each crop is discussed separately, for instance, with reference to its importance, world production, the trend and historical development of production in the United States, factors affecting production (including soil, climate, diseases, and insects, as well as some special economic factors), and the problems of marketing, quality, domestic uses, and exports. Costs of production and crop position are discussed in special chapters after the individual crops.
