Organic waste treatment and C stabilization efficiency

Our purpose was to determine whether or not aerobic and anaerobic waste treatment differ in the conservation of waste C. The stability of waste C was evaluated by determining mass losses of C during aerobic and anaerobic waste treatment and CO2 evolution during decomposition in soil using materials of the same origin. During waste treatment, mass losses of C were highest in the aerobic treatment and composting and lowest during anaerobic waste treatment. Following their application to soil, the amount of CO2-C evolved from wastes was highest from aerobically-treated material, intermediate from non-decomposed material and lowest from aerobically-treated and composted waste. Measured in terms of the decomposition of waste C during treatment and in the soil, the effect on the C stabilization efficiencies of the various waste treatment was ranked as follows: aerobically-treated and composted > non-decomposed > anaerobically-treated. It was pointed out that the larger N recirculation through anaerobically-treated wastes may be of equal or greater importance for the maintenance of soil organic matter contents in agricultural soils compared with the higher stabilization of waste C against decomposition. On the other hand, for reclaiming degraded soils, aerobically-treated (composted) wastes are better than anaerobically-degraded wastes. (C) 1997 Elsevier Science Ltd.