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Abstract
Nutrient content and pH of precipitation samples collected at six sites during 1971-1973 were studied to determine the reaction of rainfall and snowmelt and the amounts of N, S, and P added by precipitation over Iowa. The amount of NH
4-N added by precipitation per hectare annually at each site was about equal to that added as NO
3-N. The amounts of inorganic N added per hectare per year ranged from 10 kg in north-central to 14 kg in west-central Iowa, and the annual amounts of SO
4-S added per hectare ranged from 13 kg in northeastern to 17 kg in north-central Iowa. It is estimated that, on average precipitation adds about 0.6 kg of NH
4-N, 0.6 kg of NO
3-N, and 1.5 kg of SO
4-S per hectare monthly in Iowa. However, the data indicated that, on an annual basis, the contribution of precipitation to P in soil is very small; at the most, about 0.1 kg of water-soluble PO
4-P was added per hectare annually in Iowa. No NO
2-N could be detected in any of the precipitation samples analyzed. Average pH value of the rainfall and snowmelt samples collected at each site during each year was about 6, individual samples seldom reached as low as pH 4. The data indicate that the concentration of SO
4-S in precipitation in this region is seasonal, high during fall and winter and low during spring and summer.
Parent Publication
Citation
Tabatabai, M. A.; Laflen, J. M. 1976. Nutrient content of precipitation over Iowa. In: Dochinger, L. S.; Seliga, T. A., eds. Proceedings of the first international symposium on acid precipitation and the forest ecosystem; Gen. Tech. Rep. NE-23. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 293-308
