Changes occurring in the organic matter during the decomposition of compost heaps

Abstract

1. The decomposition of the organic matter of four medium to large-scale composts has been studied by analysis of samples taken at intervals.2. The bulk materials of the composts were grass-cuttings, oat-straw, Sphagnum peat and an Eriophorum and Sphagnum peat. All were made up to the same nutrient-content and relative water content.3. The analytical method used was a modification of the scheme of proximate analysis used by Waksman and by Shewan. It was supplemented by ammonia and nitrate determinations, using Olsen's method.4. Observations.A. All composts.(i) An increase in ammonia, water-soluble nitrogen and water-soluble organic matter took place during the first month.(ii) Only low nitrate concentrations were developed.(iii) Very closely parallel changes in H2SO4-soluble nitrogen and residual nitrogen were recorded.(iv) Other nitrogen changes can be described as slight and on the whole as mutually compensating fluctuations.