Selective Loss of Plant Nutrients by Erosion
1953
Stoltenberg, N. L. | White, J. L.
Losses of soil and plant nutrients have been determined for six 3-acre watersheds under prevailing farming practices, and six 3-acre watersheds under a conservation farming system. The period reported, 1947–1950, was found to be close to normal with respect to rainfall. Comparative loss data was also obtained for the four crops represented on the watersheds, namely, corn, soybeans, wheat, and meadow. Erosion was found to be a selective process such that the eroded material contained considerably more plant nutrients than the soil from which it was eroded. This selective process resulted in a decrease in soil fertility, a decrease in organic matter, and changes in texture. The selective nature of the erosion process was found to be due to energy limitations of the runoff. It was found that as selective erosion progressed, the availability of certain soil fractions may be changed, which limited the selection. For areas under cultivation, the effects of selective erosion were found to be accentuated by increases in the availability of the more valuable soil constituents as a result of plowing, cultivation, or rill development. Evidence was obtained in contradiction to the concept that slight or geological erosion is a beneficial soil forming process.
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