Nitrogen Mineralization in Sewage-sludge-Amended Coal Mine Spoil and Topsoils1
- Gerard Voos and
- B. R. Sabey2
A 16-week laboratory incubation was conducted to determine the rate of net N mineralization in sewage-sludge-amended coal mine spoil, two topsoils, a 1:1 mixture of the spoil with each topsoil, and a quartz sand. Sewage sludge was added at rates of 0, 40, 80, and 120 Mg ha−1, which added 0, 1630, 3260, and 4890 kg N ha−1, respectively. The total amount of inorganic N that accumulated during the experiments increased significantly as the rate of sewage sludge addition increased in each of the materials and mixtures tested. However, the rate of sludge addition did not have a similar effect on the amount of NO3-N accumulated. The soil materials did affect the amount of NO3-N that accumulated in 16 weeks. Little or no NO3-N had accumulated in any of the sand treatment samples and only small amounts were produced in the spoil. Ammonium-N increased with increasing rates of sewage sludge in all materials and mixtures examined. The rate of ammonification was more stable after the 8-week sampling interval in most cases. Mineralization of organic N added with the sewage sludge varied between 10 to 34%. At all rates of sludge addition, more organic N was minerlized in stock piled topsoil than in the other materials. A nonlinear least squares regression equation for N mineralization as first-order kinetics slightly overestimates N mineralization in the 4- to 8-week interval and slightly underestimated N mineralized through 16 weeks.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © . .