Nitrogen And Phosphorous Dynamics In Cocomposted Yard Trimmings And Broiler Litter |
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| Authors: | GK Felton LE Carr C E Prigge JC Bouwkamp |
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| Institution: | 1. Biological Resources Engineering Department, University of Maryland, College Park, Maryland;2. Natural Resources Sciences and Landscape Architecture, University of Maryland, College Park, Maryland |
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| Abstract: | Total phosphorus, water-soluble phosphorus and total nitrogen concentrations in cocomposted yard trimmings and broiler litter were quantified in a 2 m wide × 1 m deep × 55 m long channel composter using batch mixing. The batch mixing occurred by using a rotor tiller type turner mounted on rails for the length of the composting channel. Phosphorus and nitrogen concentrations of the compost were measured as they varied with treatment and time during a 63 day compost process followed by a 30 day curing time. The treatments contained a single mix of 50% yard trimmings, 50% poultry litter, by volume, using four aeration and turning treatments. The first treatment was a control, which received no turning or aeration unless the moisture content dropped to 40% and additional water was added to bring the mix up to 50-55% moisture, mix consolidation was required, or mixing to obtain accurate samples and moisture contents, as necessary. Both treatments two and three were aerated by negative pressure ventilation. Treatment two was turned only when the moisture content dropped to 40% and additional water was added to bring the mix up to 50-55% moisture while treatment three was turned every two weeks or sooner if the moisture content approached 40% and additional water was added to bring the mix moisture up to 50-55%. Treatment four was not provided aeration but was turned, on a daily basis and additional water added as necessary, when the moisture content dropped to 40%, to bring the mix moisture up to 50-55%. Total phosphorus increased during the compost process while water-soluble phosphorus decreased during the 63-day active composting cycle from a high of slightly more than 1600 mg P/kg to a low of slightly less than 100 mg P/kg. Once the blowers were turned off and the mixes were no longer turned, soluble phosphorus concentrations were similar for all four treatments. However, after the 93 day cycle was complete, treatment one had almost twice the water-soluble phosphorus concentration as found in treatments two, three, and four. Total nitrogen increased during the final 30 days of the process for all four treatments. The increase was between 0.1 and 10 percent. No logical cause and effect has been established and this difference is believed to be random. |
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