Effects of Carbon to Nitrogen Ratio and Turning Frequency on Composting of Chicken Litter in Turned-Windrow Piles

Abstract

Raw chicken manure was co-composted with sawdust in turned-windrow piles to understand the effects of carbon to nitrogen (C:N) ratio and turning frequency (TF) on composting. Carbon to nitrogen ratios of 20:1, 25:1 and 30:1, and turning frequencies of every 2 days and every 6 days were experimented. Properties of the chicken litter (chicken manure + sawdust) periodically monitored during the composting process were moisture content (MC), temperature, pH, total nitrogen (TN), total carbon (TC) and C:N ratio while dry matter (DM), total phosphorus (P) and total potassium (K) were examined at the end of composting. During composting, MC of the piles was periodically replenished to 55%. The results showed that C:N ratio had significant (p ≤ 0.05) effect on pile temperature, TN, TC, C:N ratio, DM, P and K while TF had significant (p ≤ 0.05) effect on pile temperature, pH, TC, C:N ratio and K. A significant part of the TN losses were attributed to NH3 volatilization while that of the TC losses were attributed to OM degradation. It was observed that moisture loss increased as C:N ratio and TF increased. All treatments reached stability at about 87 days as indicated by the decline of pile temperatures to values close to ambient temperature.