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Title: EFFECTS OF LONG-TERM SOIL ACIDIFICATION DUE TO AGRICULTURAL INPUTS IN WISCONSIN

Author
item BARAK, PHILLIP - UNIV. OF WI-MADISON
item JOBE, BABOU - UNIV. OF WI-MADISON
item KRUEGER, ARMAND - UNIV. OF WI-MADISON
item PETERSON, LLOYD - UNIV. OF WI-MADISON
item Laird, David

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sustainability of U.S. agricultural productivity depends on development of management systems that maintain or enhance soil quality. Since the 1950's large amounts of artificial nitrogen fertilizers have been applied to agricultural soils. The use of nitrogen fertilizers has greatly increased production of food and fiber. We found that the ability of one soil to hold mineral nutrients decreased by 16% as a result of 30 years of high nitrogen fertilization. The results indicate that the use of high rates of nitrogen fertilizers without lime or organic matter inputs will over time significantly degrade soil quality. The knowledge generated by this research may be used to develop better management systems for agricultural land which will benefit farmers by improving the quality of their soil and consumers by improving agricultural productivity.

Technical Abstract: Agroecosystems are domesticated ecosystems intermediate between natural ecosystems and fabricated ecosystems, and occupy nearly one-third of the land areas of the earth. Chemical perturbations as a result of human activity are particularly likely in agroecosystems because of the intensity of that activity, which include nutrient inputs intended to supplement native nutrient pools and to support greater biomass production and removal. At a long-term fertility trial in south-central Wisconsin, significant depletion of exchangeable Ca**2+ and Mg**2+, increases in exchangeable acidity, decline in CEC, and decline in base saturation have been noted in association with application of ammoniacal N fertilizer. Plant analysis shows that a considerable portion of the alkalinity generated by assimilation of N (and to a lesser extent by S) is sequestered in the above-ground plant parts as organic anions and is not returned to the soil if harvested. Elemental analysis of Ca-saturated soil clays indicates an irreversible loss of 16% of the CEC of the soil clay and minor increases in Fe and Al. The reversibility of these changes due to prolonged acidification is doubtful if the changes are due to soil weathering.