Verification of agricultural cleaner production through rice-duck farming system and two-stage aerobic composting of typical organic waste

This study aimed to build a clean agricultural production system in small watersheds through rice-duck farming system, farmland ecological ditch, two-stage aerobic composting of typical organic waste and returning the compost product to the field. The results showed that the final product of two-stage aerobic composting, with sludge, pig manure and rice straw as raw materials, has better maturity and humification (C/N: 15.2; GI: 112%; Humification: 4.78; Humic fractions: 22.1% of OC). After composting, the physical and chemical properties of the composted products were improved, the microcystin further degraded, and the spatial structure further optimized. The quality of final compost products from different batches of continuous operation within six months totally meets the requirement of organic fertilizer standard, and most nutritional elements in algae sludge, pig manure and rice straw were retained. Mechanism analysis shows that the reduction of the TOC and C/N ratio and the increase of the pH, EC, and TN were all conducive to the maturity and humification of the final compost. In addition, the application of nitrogen fertilizers and herbicides in the rice planting process under the rice-duck farming system has been reduced by 10% and 50%, respectively. Furthermore, the rice-duck farming system increased the economic income of rice per hectare by $1523.9. The agricultural cleaner production through rice-duck farming system and two stage aerobic composting of typical organic waste can achieve pollution load reduction and waste resource utilization, which has both economic and environmental benefits.