Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2000
Publication Date: 5/1/2001
Citation: BALKCOM, K.S., ADAMS, J.F., HARTZOG, D.L., WOOD, C.W. MINERALIZATION OF COMPOSTED MUNICIPAL SLUDGE UNDER FIELD CONDITIONS . COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS. 2001.
Interpretive Summary: Nutrient release from sludge may vary due to sludge type and composting material. This study determined release of selected nutrients from sludge to evaluate optimal land application rates under field conditions. Composted municipal sludge was studied in two on-farm experiments and a field incubation study. The on-farm studies were used to determine release of selected nutrients over a growing season, while a field incubation study measured nutrient release at different times for an entire year. Nitrogen was not released, while phosphorus was released from sludge at one field site, however the opposite occurred at the other site. The incubation study showed that the sludge released calcium, magnesium, and zinc into the soil after 1 yr. Calcium had the highest increase followed by magnesium and zinc. There was an initial release of all nutrients studied from sludge during the first 2 weeks of the incubation. Results show that under field conditions, sludge may not supply nutrients in concentrations that would support annual crop growth.
Technical Abstract: Mineralization of nutrients from composted municipal sludge may vary due to sludge type and composting material. This study determined mineralization and release of selected elements from composted municipal sewage sludge to evaluate optimal land application rate under field conditions. Composted municipal sludge was studied in two on-farm experiments, at rates of 0.0, 2.0, 4.0, and 8.1 Mg ha-1 (dry wt. basis) applied to peanuts and another field incubation study consisting of 0.0 and 4.0 Mg ha-1 sludge rate (dry wt. basis). The on-farm studies were used to determine release of selected elements over a growing season, while a third field experiment measured nutrient release periodically for an entire year. The on-farm studies used soil cores with resin bags placed on the bottom to trap any leached nutrient, while the soil in the PVC core was extracted to determine nutrient release. In the latter study, decomposition bags with soil cores and resins were utilized to help determine the rate of nutrient release from the sludge. Nitrogen (N) was immobilized, while phosphorus (P) was mineralized at Site A from municipal sludge, but the opposite occurred at Site B. Net release of calcium (Ca), magnesium (Mg), and zinc (Zn) into the soil from sludge occurred after 1 yr. Greatest increase was Ca, at 16 mg kg-1 followed by Mg and Zn at 2 and 0.8 mg kg-1, respectively. There was an initial release for all nutrients studied from sludge during the first 2 weeks after soil incorporation. Results show that under field conditions, nutrients from these organic amendments can be readily immobilized, but not supply selected elements in concentrations that would support annual crop growth.