A priori , it cannot be determined which inputs would be increased in response to an increase in output returns in a multi-input technology. Basically the argument is that farmers can replace purchased inputs through a rotation that incorporates summerfallowing which helps improve fertility and aids in weed control, and conserves moisture. As crop returns increase, the value of land increases while the prices of other inputs generally remain constant. Producers are encouraged to use more purchased inputs and less summerfallowing. Some of the direct linkages from production decisions to the environment were alluded to above.
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.