Cultural Practice Changes Leaving crop residue on the soil surface generally reduces the amount of water runoff, particularly for water applications of one inch or less. Crop residue works in a number of different ways to reduce runoff and erosion. When water droplets strike a bare soil surface, energy contained in the droplets is transferred to the soil, often forming a crust. Although this crust is normally less than 0.1 inches thick, it can reduce the infiltration rate by more than 50 percent. Residue effectively absorbs much of this impact energy, reducing crust formation.
Residue increases the soil surface roughness, which helps dissipate the energy from flowing water.
This, in turn, reduces the amount of erosion that occurs. The intricate series of small dams created by the residue increases both the amount of water stored on the soil surface and the time available for water to infiltrate into the soil. Finally, residue reduces soil moisture evaporation, thus potentially reducing the number of irrigation events. The type of crop residue is not critical. The key is to leave an adequate amount of well-distributed residue on the soil surface.