Performance characteristics of three aeration systems in the composting ofsheep manure and straw

Composting of sheep manure mixed with straw was carried out in a pilot plan t using three different systems of aeration: pile turning; forced aeration of static pile; and passive aeration of static pile. The aim was to investi gate which of these three systems was the most appropriate for the manageme nt of the manure and straw. The effects of the such composting systems on t he effectiveness of composting were examined by measuring parameters such a s temperature, pH, organic matter content, moisture content, changes in pol ysaccharide, carbon and nitrogen content. Different hydrolases activities o f agricultural interest (urease, phosphatase, fl-glucosidase and cellulase) which are involved in the nitrogen, phosphorous and carbon cycles were als o determined. The analysis of all three composts obtained showed similar ch aracteristics. In the passive aeration system, much of the capital and oper ating costs are reduced since neither the heap needs turning nor is a force d aeration system required. Besides, this system has the lowest nitrogen lo ss, so it could be considered as the most advisable system for small farms. (C) 2001 Silsoe Research Institute.