Influence of clay as additive on greenhouse gases emission and maturity evaluation during chicken manure composting

To assess the impact of clay as additive on compost maturity and reduction of greenhouse gases (GHGs) as well as ammonia emission during chicken manure composting. Six treatments with different dosages of clay (0%, 2%, 4%, 6%, 8% and 10% clay added by dry weight basis of chicken manure and wheat straw) were designed to conduct an aerobic composting experiment for 50 days. The results showed that the clay amendment could prolong the thermophilic phase and reduced the maturity period of composting. In addition, the GHGs (N2O and CH4) and ammonia emission of clay added treatments were reduced by 25.3-63.4%, 26.01-50.24% and 8.5-70.5%, respectively. But CO2 emission was significantly higher in 10% clay amended treatment. Furthermore, the redundancy analysis showed that C/N ratio and total organic matter among all physiochemical properties had significant relationship with GHGs and ammonia emission. Therefore, this study shown that clay addition can promote maturity, reduced GHGs emission and improve the quality of product.