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Many municipalities have examined composting as an alternative to landfilling for the management of organic solid waste materials. Ultimately these materials will be land-applied and therefore some knowledge of nutrient availability will be necessary to optimize crop yield and minimize environmental risk. Field studies were conducted in 1993 and 1994 on a silt loam and a loamy sand soil in Wisconsin to determine the effect of municipal solid waste compost (MSWC) on corn (Zea mays L.) yield, plant nutrient concentration, and soil nitrate N content. Municipal solid waste composts with ages of 7, 36, and 270 d were applied at rates of 22.5, 45, and 90 Mg ha(-1) to small plots. Rates of commercial nitrogen (N) fertilizer, ranging from 0 to 179 kg N ha(-1), were applied to separate plots to determine the N availability from the MSWC. Treatments were applied in the spring and incorporated before planting corn. The 270-d MSWC increased corn whole-plant dry matter and grain yield at each location in both years above the 7- and 36-d MSWC. Rate of MSWC only affected grain yield at the loamy sand site in 1994. Municipal solid waste compost had minimal effect on the levels of plant nutrients in the whole-plant tissue measured at physiological maturity. Nitrate N measured in the top 90 cm of soil was higher throughout the growing season in treatments receiving recommended N fertilizer when compared with any of the MSWC treatments. It was estimated that 6 to 17% of the total N in the 270-d MSWC became available in the first year. The land-application of mature MSWC at the tested rates would be an agronomically and environmentally admissible practice.
R. P. Wolkowski (Mon,) studied this question.