The role of feed composition on the composting process. I. Effect on composting activity

Abstract

In this study the influence of four feed augmentations on a commercial composting mixture have been investigated in a systematic manner using controlled laboratory experiments. The four feed augmentations studied were: grass clippings, leaves, cabbage and soya bean meal. Based upon the analysis of temperature/time data for the various composting systems, measurement of respiration rates, and physical and chemical characterization of the various materials, some scientific conclusions can be drawn. The addition of grass up to levels of about 30% can be tolerated. However, due to high moisture levels associated with grass, additional bulking agents may be required to accommodate higher grass loadings. The presence of high loadings of leaves in autumn may cause some retardation of the composting activity necessitating longer composting times. High moisture vegetables, such as cabbage, can pose processing problems when present in high loadings. Although these vegetables are easily compostable, the release of high water levels needs to be addressed if anaerobic activity is to be avoided. High levels of proteinous materials need to be balanced with cellulosic matter in order to minimize anaerobic activity. This arises because of their nutritional effect which results in high composting activities and a severe depletion of oxygen.