ABSTRACT
The soil conservation job in America is now about one-third done but two-thirds remains to be done. Soil losses from land erosion contribute sediment to the streams of America. Sediment yields range from 3 to 10 tons per acre per year from large watersheds, for much of this country.
The value of the plant nutrients removed by soil erosion from the lands of America is $800 million per year. The damage caused merely by the presence of the sediment particles in the stream waters of America is estimated to be $260 million per year.
Strong new action programs are under way to control the pollution of streams. For most uses, the presence of sediment particles in water is injurious. Consequently sediment in streams is a pollutant, and it should be recognized as such. Pollution control programs should include efforts, regulations, and even laws to prevent stream pollution by sediment.
For 35 cities in Illinois hydrologic analyses showed that as a reservoir loses its capacity to sediment, the water supply yield of the reservoir is decreased proportionately.
Soil conservation programs can reduce sediment yields dramatically to allowable levels. In eight reservoirs throughout the country, sedimentation surveys have documented reductions in lake sedimentation; 28 percent reduction in one case and 73 percent in another.
The elements of a soil conservation program are well defined: contour farming, strip cropping, lengthened crop rotations to include more pasture or grass, and other specialized measures. These practices allow man to use the land effectively as a permanent resource. Further adoption of these practices will reduce sediment yields and will abate the pollution of our streams by sediment particles.
