Comparisons of Compost Maturity Indicators for two Field Scale Composting Systems

ABSTRACT: Application of immature compost to crops has negative effects on crops; robbing them of oxygen and nutrients that are immobilised by other microorganisms. Temperature, germination index (GI) and pH parameters were monitored for thirteen weeks to compare the rate of compost maturity in passively aerated and actively aerated composting systems: Dome Aerated Technology and Turned Windrow System. Germination indices recorded were low initially in both systems and varied as the process progressed till the later weeks when they increased steadily to the thirteenth week. There were no significant differences between pH and germination index values recorded in both systems at ? = 0.05. The pH values in both systems fell within 6.5-8.5. Both systems gave high quality compost and maturity rates were not significantly different. Though there was no significant difference between the germination index values in both systems at ? = 0.05, the temperature trends and the higher germination index recorded in the T-W system gives an indication of a higher compost maturity as compared to the DAT system. Germination index analysis of finished compost in both systems exceeded 150%, indicating an absence of phytoxins in the final compost product.