Assessment of Physico-chemical, Microbial and Phytotoxic Changes of Various Organic Wastes During their Composting Process

Abstract

In this study, the aerobic composting in windrows of five mixtures of organic materials was compared. Composting temperatures rose to 60-67°C within 7 to 22 days and stayed above 45°C for 4-5 months before declining. Decomposition after 223 days was 40-43% for organic materials and 23-25% for carbon. The pH values decreased during the composting process and became neutral at maturation. Electric conductivity dropped to 3.6-5.22 mS/cm after 170 days. Dry matter increase to 96.2-97.8% within 182 days of composting and dropped to 70.13-73.87% at maturation. Bulk density increased from 0.20-0.26 g/cm3 to 0.34-0.55 g/cm3 and varied depending on composts. Porosity and water retention decreased during composting. Nutrient contents varied over composting times and wastes. Composts' phytotoxicity, evaluated on barley (Hordeum vulgare L.) seeds, decreased by 0.2-13.2% and 63.2-81.3% after 30 and 220 days of composting, respectively. Benefits of composting organic wastes into agriculturally valuable final products was discussed.