Stability and maturity of maize stalks compost as affected by aeration rate, C/N ratio and moisture content

To estimate the order of importance of factors affecting the stability and maturation of compost, cow feces and maize stalks were co-composted at different aeration rates “AR” (22, 44 and 66 L kg-1 DM . min-1) of C/N ratios (16, 19, 22), and moisture contents “MC” (60 %, 65 %, 70 %). A composting process was monitored by physical and chemical methods. The thermophilic phase with all treatments was long enough to meet sanitation requirements. The emitted carbon dioxide and the losses total organic carbon and total extractable carbon increased with increasing aeration rate, there was a significant difference between the treatments with low and high aeration rate, but no significant differences between those two treatments and the moderate aeration rate. The total nitrogen contents of all treatments decreased during the thermophilic phase, while it was increased after that for all treatments except T8. The compost with the highest initial C/N ratio was significantly different from the other treatments and had the highest values of humic substances, degree of humification and humification rate. The compost with the lowest initial C/N ratio was significantly different from the other treatments and had the lowest germination index (57–67%). Aeration rate was the main factor influencing compost stability, while the C/N ratio mainly contributed to compost maturity, and the moisture content had an insignificant effect on the compost quality. The recommended parameters for composting are an aeration rate of 0.44 L kg-1 DM. min-1 and a carbon to nitrogen ratio of 19 with moisture content of 60–70%.