Sometimes more costly structures such as grassed waterways and terraces are required to provide the necessary control. Conservation tillage, which reduces soil disturbance and preserves residue cover on the land, is another effective way to reduce erosion. Figure 2 . Strip-cropping provides an efficient means of controlling runoff problems. The benefits to water quality of several widely used conservation practices are shown in Table 1.
Various practices enhance surface water quality by controlling erosion.
Some of these have little effect on groundwater. The careful use of fertilizers, animal wastes and pesticides is a widely applicable approach that benefits our groundwater. It is essential to apply management practices that protect both surface and groundwater quality. Soil properties and crop needs determine the proper amounts of fertilizers and pesticides to apply and the timing and method of their application. For example, sandy soils cannot hold as large a quantity of nutrient elements and other absorbed materials as can more clayey soils.