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

Composting of sheep manure mixed with straw was carried out in a pilot plant using three different systems of aeration: pile turning; forced aeration of static pile; and passive aeration of static pile. The aim was to investigate which of these three systems was the most appropriate for the management of the manure and straw. The effects of the such composting systems on the effectiveness of composting were examined by measuring parameters such as temperature, pH, organic matter content, moisture content, changes in polysaccharide, carbon and nitrogen content. Different hydrolases activities of agricultural interest (urease, phosphatase, fl-glucosidase and cellulase) which are involved in the nitrogen, phosphorous and carbon cycles were also determined. The analysis of all three composts obtained showed similar characteristics. In the passive aeration system, much of the capital and operating costs are reduced since neither the heap needs turning nor is a forced aeration system required. Besides, this system has the lowest nitrogen loss, so it could be considered as the most advisable system for small farms. (C) 2001 Silsoe Research Institute.