Nitrogen mineralization from field-applied beef cattle feedlot manure or compost

To apply manure or compost to fulfill N requirements of a crop, the amount of N mineralized in actual field conditions needs to be determined. Nitroge n mineralization from composted and non-composted beef cattle feedlot manur e applied to no-till and conventional tillage systems was determined under field conditions for 3 yr. Manure, composted manure, and inorganic fertiliz er were applied to provide for N needs of corn. A no-treatment check was al so included. An in situ resin method was used to determine N mineralization from a soil receiving manure, compost, and no treatment during the growing season (June-October). Of the organic N applied the previous autumn, appro ximate to 11% was mineralized from composted manure and 21% from noncompost ed manure during the succeeding growing season. Lower N availability from c ompost reflects the loss of easily convertible N compounds during compostin g and the presence of stable N compounds. Nitrogen mineralization was simil ar in the no-till and conventional tillage systems even though manure and c ompost were surface-applied in the no-till. Nitrogen mineralization was sig nificantly, but not closely (R-2 = 0.21), related to thermal unit (cumulati ve mean daily temperature >0 degreesC). Mineralization rate constants indic ated that availability of residual manure and compost N was less than expec ted. The in situ mineralization approach seems to be a good method of measu ring N mineralization during the growing season or during periods when the soil is not frozen or excessively dry. Nitrogen mineralization needs to be considered when manure and compost are used for an environmentally acceptab le crop production system.