Effect of Rape Straw Ratio on Performance of Aerobic Composting Process and Characteristic of Final Product

Abstract:

Composting is an effective method to convert crop straw into organic fertilizer. To maximum utilize rape straw, the effect of rape straw ratio on performance of aerobic composting process and final product was investigated. The rape straw proportion in feedstocks in R1, R2 and R3 were 45, 65 and 85% (wet weight), respectively. The results showed that organic matter degradation in R1, R2 and R3 occured mainly in the early stage of composting process, and achieved 34.06, 35.57 and 39.78%, respectively at the end of composting process. In addtion, the degradation of organic matter conformed to the first-order kinetic model. Comparing the physicochemical properties of samples during the composting process, the end-product of R3 satisfied all the maturity indicators recommended by previous references. In the end-product of R3, NH4+ was not detected, and the total nitrogen content, NO3- concentration and germination index (GI) achieved 2.17%, 1,844.93mg•kg-1 (dry weight) and 102.66%, respectively. In conclusion, rape straw with higher addition amount enhanced the utilization efficiency of rape straw, and enhanced the quality of the end-product. Moreover, nitrogen loss reduced with increasing rape straw addition amount in the present experiment scope.