 |
Home | Search | Browse | About IPO | Staff | Links |
|
Home | Search | Browse | About IPO | Staff | Links |
Letters Disappearing soil EDITOR: I compliment Illinois Issues and author James Krohe Jr. for the comprehensive article on "Illinois' disappearing soil" (September 1981). One very important point in the article should have been examined more critically: the statement that "annual soil losses of between two and five tons per acre are tolerable, because that much new topsoil per acre is created each year." This contradicts numerous citations by Pimentel and others in Science that soil formation at a rate of 5 tons per acre per year is expected only "under ideal soil management conditions." A more realistic rate "under normal agricultural conditions" is 1.5 tons per acre per year. Dr. Robert Betz, professor of biology at Northeastern Illinois University and research associate in botany at the Field Museum, has estimated that 6 inches of the average 16 inches of prairie topsoil in Illinois has been lost to erosion, based on comparison of topsoil left on agricultural land with topsoil in undisturbed pioneer cemeteries. During the 100-plus years of agriculture in Illinois, the rate of soil formation apparently has not kept pace with erosion. No one, to my knowledge, has actually measured rates of soil formation under different types of cropping systems in Illinois. Volume III of the Water Quality Management Plan for Illinois candidly admits that "the tolerance of one to five tons represents the collective judgments of soil scientists in the Soil Conservation Service, Agriculture Research Service, and State Agricultural Experiment Stations." Until we have measurements, instead of judgments, of soil formation rates, we cannot establish tolerable erosion rates that will guarantee a "permanent" or "sustained" agriculture on perpetually replenished topsoil. If "tolerable" erosion rates established by government agencies exceed soil formation rates, we run the risk of eventually "mining out" the topsoil. Richard E. Sparks IN REPLY: Mr. Sparks is quite correct. But the phrase, "tolerable soil loss standard, "has a political as well as a scientific meaning in Illinois. Conservation professionals worry that farmers will not be able to meet even the 5-ton goal on all the state's farmland by 2000. Meeting a more stringent 1.5-ton standard would cost vastly more for erosion control and conversion of row crop land to less erosive uses, more than either farmers or taxpayers are likely to be willing to pay. The difference between 5 tons and 1.5 tons is the difference between what is necessary and what is possible. Jim Krohe Jr. Breaking of the prairie EDITOR: I would like to compliment you, and Contributing Editor James Krohe Jr., on the excellent article, "The breaking of the prairie," which appeared in the October 1981 issue of Illinois Issues. This is one of the finest articles on the overview of Illinois farmland conditions that I have ever read. It was well-researched and Mr. Krohe should be congratulated. Merle H. Glick 30 | December 1981 | Illinois Issues |
|
|