Knowledge of the biology of crops, their production processes, and relations with environment is a central issue in crop ecology. Placing this knowledge into practical farming systems is another. At this point we give attention to how farm management joins ecological principles and technology in the design of cropping practices. Given the possibility to select a portion of the annual cycle for production, to choose appropriate cultivars and spacings, and to modify environment by tillage, drainage, fertilization, weed control, correction of soil pH, and other means, the range of management options is extremely broad. Ecological factors determine what may be grown and where, but human decisions about labor supply, economics, and available technology are equally important in management.

We attempt to bridge this gap by considering technologies for soil management in Chapter 12, how cropping practices may be adapted to supplies of water in Chapter 13, and how water supply may be enhanced through irrigation in Chapter 14. Dependence of farming on external energy and whether energy supplies may be adequate in the future are addressed in Chapter 15. One's picture of farming remains fuzzy, however, until the operation of representative farms is considered in detail. Two imaginary farms, one Australian and one American, are constructed in Chapters 16 and 17 as models to assist readers in further analyses of farming systems of importance to them.

How modern agriculture may evolve in an uncertain future is considered in Chapter 18. Many in society, because of disillusionment with technology, concerns about environment, or political reasons, now attack the premises and methods of modern agriculture.