Humans depend on agriculture to provide food, feed, fiber, and fuel. Production of these organic materials in individual fields depends upon the physiological abilities of plants and the soil and aerial environments in which they grow. What crops are grown, and how, are human decisions that depend upon usefulness and value of products, costs of production, and risks involved. At the farm level, those considerations are rationalized with need for animal feeds, availability of labor, and requirements for crop rotation to raise fertility and control disease, weeds, or erosion. Additional constraints are imposed by market forces and availability of capital and technology.

Within these socioeconomic considerations, crop response to environment and management follows the laws of thermodyamics and conservation of energy and mass. Therefore, we can understand and predict crop performance using ecological analyses in terms of biological, chemical, and physical principles. This is the context and content of crop ecology.

In this chapter, we introduce ideas about the nature, objectives, and management of farming to provide a foundation for detailed analyses of crop performance in agricultural systems. We also present the guiding principles upon which this book is constructed.

On the nature of agriculture

Agriculture can be studied at various organizational and geospatial levels, from individual fields, to their grouping in farms, and to grouping of farms within regions. This is illustrated in Fig. 1.1 and identifies the need to establish a coherent terminology.