Excerpt
CURRENT use of critical phosphorus (P) concentrations in determining runoff water quality may bring about inappropriate agricultural management decisions concerning accelerated eutrophication.
P is an essential element for plant growth. Its application to agricultural land often improves crop production. But the transport of P from agricultural land in runoff can result in a deterioration of water quality from accelerated eutrophication. Eutrophication of surface water creates problems with the use of water for fisheries, recreation, industry, or drinking due to the increased growth of undesirable algae and aquatic weeds.
These problems resulted in critical levels for soluble P—10 micrograms per liter—and total P—20 micrograms per liter—being suggested as concentrations that, if exceeded, may accelerate the eutrophication of lakes and impoundments (2, 3, 5). The critical-P-level approach and the suggested concentration levels were subsequently adopted and modified by certain federal and state agencies as a measure of water quality (1, 4). A recent study of the eutrophic status of almost 200 lakes concluded that the original tolerance levels of …
Footnotes
A. N. Sharpley, S. J. Smith, and R. G. Menzel are soil scientists at the Water Quality and Watershed Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Durant, Oklahoma 74702. A. N. Sharpley holds a faculty appointment at Oklahoma State University.
- Copyright 1985 by the Soil and Water Conservation Society
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