Agricultural production occurs within a managed environment over broad landscapes. In most agricultural regions the natural landscape of woods, grasslands or marshes was modified by modern agriculture. The natural biological system has been altered as farmers now generally monocrop non-native plants using a variety of manufactured inputs which require the soil to be disturbed continually. Figure 4 shows the basic system of relationships that exists which link agricultural production activities to soil, water, the atmosphere and the surrounding landscape. Anderson and Strutt 1996, p. 156.
Tillage affects the soil and the surrounding environment.
Tillage is used to prepare a seedbed and remove and control unwanted plants. Tillage can commence right after harvest, followed by a number of spring operations up to seeding and include cultivation during the growing season for some row crops. Although smooth bare fields are an indication of a new cycle of production and harvest, soil left unprotected by plant cover is susceptible to erosion by rain and wind. Brown streams, gullies in the fields and blowing dirt are the obvious signs that erosion is occurring. Agricultural productivity is based solely on the thin layer of topsoil in which crops are produced.