Abstract
A newsprint, pulp and paper sludge was evaluated as a soil additive/amendment at 0, 8, 15, 31, 62, 123, and 246 Mgfta for growth of alfalfa (Medicago sativa) and bluegrass (Poa pratensis) under greenhouse conditions. Bluegrass biomass increased by 300%, and protein content increased by 27% at 246 Mg/ha compared to the unamended soil. Alfalfa biomass was unaffected by sludge application rate, but protein content increased by 12%. No net nitrogen (N) immobilization was observed. A comparison of single and double exponential N mineralization models showed that the two pool model more closely fit the N mineralization data obtained from a laboratory incubation study. The two pool model was then used to develop linear regression equations to estimate appropriate sludge application rates based on the rate of N mineralization.
Notes
Contribution from the University of Idaho Forestry, Wildlife and Range Experiment Station. Paper No. 669.