Impact of agricultural practices on soil food web structure: Theory and application

Abstract

Studies on the effects of agricultural practices have increasingly taken a a systems perspective. A comparison of five long-term (5–10 year) systems level studies on native and agricultural soils ranging from the North American Shortgrass Steppe to recent Polder soils in the Netherlands demonstrates that systems exhibit common responses to agricultural disturbances. For example, management practices that incorporate organic material (stubble-mulching and conventional practices) disrupt the temporal and spatial compartmentalization of the bacterial and fungal energy channels of soil food web. Under these practices, the bacterial energy channel tends to be more active than the fungal energy channel. However, management practices that minimize the disruption of top-soil (notillage and integrated farming) tend to maintain temporal and spatial compartmentalization of the bacterial and fungal energy. In these practices, the fungal energy channel is either dominant or is more active than in more disturbed sites in the same soils. Coincident with the change in structure are changes in nutrient dynamics. Having established patterns in the ways in which agricultural practices alter food web structure and function, the challenge will be to utilize this knowledge in the development of sustainable low-input agricultural systems.