Tillage and crop residue management effects on losses of chemicals from soils

Tillage and crop residue management both influence the losses of nutrients and crop-protection chemicals from the soil to the aqueous environment. Tillage is performed to control weeds, to modify the soil structure and often to incorporate straw, which can no longer be burnt in European Community countries. The resulting changes in the soil alter both the pathways for water flow and the activities of microbes. This paper reviews their effects on water movement and the microbial and physico-chemical processes that influence the vulnerabilities of nutrients and crop-protection chemicals to leaching. It also suggests some possible options for limiting losses of these substances from the soil. There remains considerable scope for cooperation between tillage specialists and those with an interest in the management of nutrients and crop-protection chemicals.