Effects of turning frequency on the rate of lignin degradation in composting of rice straw

Abstract

Rice straw produced during rice cultivation was collected from paddy field in order to investigate the effect of turning frequency on the rate of lignin degradation in the composting of rice straw. The effect of temperature, moisture content, pH and organic matter content during the composting process were also studied in this project. Four heaps of the compost mixtures consist of rice straw and dried goat manure were piled up coinciding with the three turning frequency treatments: Pile 2 = turned daily, Pile 3 = turned every three days, Pile 4 = turned every seven days and one heap for the control treatment: Pile 1 (no turning). After 35 days of composting, the decreasing of lignin content was observed in Pile 2 which is found to be 3.41 wt % compared to 6.24 wt %, 8.09 wt % and 12.04 wt % in Pile 3, 4 and 1, respectively, indicating higher rate of lignin degradation. Thus, higher turning frequency was observed to promote the reduction in lignin content and increment in the rate of lignin degradation in composting of rice straw.