ABSTRACT
The disposal of straw or stubble by incorporation as opposed to burning results in changes in the physical, chemical, and biological condition of the soil and also has various effects on pests, diseases, and weeds through interactions with other components. Therefore, due consideration must be given to crop-management strategies for straw disposal and stubble management in the intercrop period between harvest and sowing and their influence on subsequent integrated crop protection. The plow has traditionally been used to loosen the soil and incorporate crop residues. Such complete inversion of crop residues has a considerable influence on mineralization of plant nutrients and leaves bare soil, which increases nitrogen volatilization to the atmosphere. It also affects the survival of beneficial invertebrates and of soilborne pests, pathogens, and weeds. In some soils, as a consequence of plowing, soil structure is frequently impaired through the development of a “plow pan.” Minimumtillage systems, which incorporate 70% of crop residues in the top soil layers and leave 30% on the soil surface, and direct drilling may affect the incidence of trashborne diseases and favor soil fauna, particularly predators of pests. Research into the long-term effects of alternative soil tillage systems, based on conditioning the soil and incorporating crop residues in one pass without inverting the soil, has shown differential effects on a range of important arable crop diseases. These effects may be largely dependent upon the inoculum source and transmission capabilities (Table 7.1) which, in turn, may have implications for crop protection.
