Nitrogen and carbon mineralization in soil amended with municipal solid waste compost

Municipal solid waste (MSW) compost contains large amounts of organic matter that can be beneficial to soil. The objectives of this study were to measure N mineralization and acid hydrolyzable N in soil amended with MSW compost and correlate corn (Zea mays L.) grain yield with acid hydrolyzable N. The soil, an Orthic Black Chernozem (Entic Hapludoll) cropped to corn, was amended with composts at either 90 dry Mg ha^-1 yr^-1 from 1993 to 1995, or at 270 dry Mg ha^-1 in one application in 1993. Soil samples were collected in the fall of 1994 and 1995 to measure C and N mineralization and acid hydrolyzable N. Potentially mineralizable N was estimated with the NCSOIL model after using C and N mineralization observed in the laboratory to calibrate the model. Net N immobilization occurred in compost-amended soils collected in 1994 with less than 0.2% of the total soil N mineralized in the compost treatments. In 1995, there was net mineralization in compost treatments but less than 5% of total soil N mineralized in 120 d. The addition of compost increased the acid hydrolyzable N of soil with 43-63% of the total soil N being acid hydrolyzable. Acid hydrolyzable soil N did not correlate to N₀ but weakly correlated with corn grain yield. The MSW compost source was more important than the timing of application in inducing differences in soil biochemical properties.