Co-Composting and Characterization of Swine Waste Solids and Its Use as a Soil Amendment in a Field Study: The Effects of Duration of Composting

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Title: Co-Composting and Characterization of Swine Waste Solids and Its Use as a Soil Amendment in a Field Study: The Effects of Duration of Composting
Author: Rivin, Jonathan M
Advisors: john j. classen, Committee Chair
Abstract: Composting is a reasonable option for managing swine wastes prior to land application. However, the process is protracted, and the loss of nutrients can be considerable, diminishing the usefulness as a plant nutrient source. For these reasons, reducing composting time has been of interest. The objectives of this research were to compost swine waste feedstocks for various lengths of time, use them as soil amendments in a field study, and subsequently relate the compost characteristics to plant response and changes in soil characteristics. Additionally, a laboratory nitrogen mineralization study was conducted to determine mineralization rates of the amendments. Swine manure solids and Paulownia branches/leaves were co-composted for 0, 3, 6 and 15 weeks. For the field study, the composts and manure were used as soil amendments; fertilized and unfertilized soils were the controls. The uncomposted feedstock-amended soil produced the greatest sorghum stover yield, although grain yields from all treatments were statistically equivalent. With respect to soil physical properties, the effect of treatment on soil bulk density was statistically significant, but for soil impedance and aggregate stability, treatment was not statistically significant. The water holding capacity was not statistically affected by treatment at either field capacity or wilting point. Compared the controls, the reduction in plant available water induced by the manure-amended soil was statistically significant. Due to the minimal effects of soil treatments on soil and plant response, relating amendment characteristics to field response was not feasible The results from a nitrogen mineralization study did not confirm the projected mineralization rates for the amendments, which were hypothesized from the literature. As the amendment application rates were based upon the projected mineralization rates, the field loading rates may have been low. However, the nitrogen mineralization dynamics in the laboratory and in the field may have been dissimilar.
Date: 2008-02-17
Degree: PhD
Discipline: Biological and Agricultural Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/4126


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