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. Nitrogen mineralization from composted and non-composted beef cattle feedlot manure applied to no-till and conventional tillage systems was determined under field conditions for 3 yr. Manure, composted manure, and inorganic fertilizer were applied to provide for N needs of corn. A no-treatment check was also 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, approximate to 11% was mineralized from composted manure and 21% from noncomposted manure during the succeeding growing season. Lower N availability from compost reflects the loss of easily convertible N compounds during composting and the presence of stable N compounds. Nitrogen mineralization was similar in the no-till and conventional tillage systems even though manure and compost were surface-applied in the no-till. Nitrogen mineralization was significantly, but not closely (R-2 = 0.21), related to thermal unit (cumulative mean daily temperature >0 degreesC). Mineralization rate constants indicated that availability of residual manure and compost N was less than expected. The in situ mineralization approach seems to be a good method of measuring 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 acceptable crop production system.