Factors Affecting the Mineralization of Nitrogen in Sewage Sludge Applied to Soils

Abstract

An investigation to determine the factors affecting the rate of N mineralization in sewage sludge amended soils using multiple regression techniques was undertaken. Five published incubation studies involving 11 different sludges were analyzed. Both soil and sludge factors were considered in the statistical analyses. Factors positively affecting mineralization rate were total N content of the soil, and the duration and temperature of the incubation. Negatively affecting mineralization were the C/N ratios of the sludge and soil. Two of the estimated equations resulting from the statistical analyses were tested on the results of a sixth incubation study in which several different sludges were incubated under the same time, temperature, moisture, and amendment rate conditions and a 0.75 correlation coefficient was obtained. The resulting model equation using data from all six studies indicated that soil factors are important variables in predicting mineralization of N in sewage sludge amended soils.