Soil Greenhouse Gas Emissions and Nitrogen Change for Wheat Field Application of Composted Sewage Sludge

This study aimed at assessing the character of greenhouse emissions under different rates of composted sewage sludge as a nitrogen fertilization substitute, founding the characteristic of soil nitrogen change and, ultimately, providing a theoretical basis for the rational utilization of composted sewage sludge in calcareous soil. Compost sludge as a nitrogen fertilizer substitute has emission reduction effects on N2O, CH4 and CO2. Compared with that of the single fertilizer application, the GHGI under the 20% sludge replacement treatment was significantly reduced by 20.15%, and the global warming potential was significantly reduced by 11.53%, while the wheat yield was increased by 4.78%. Compost sludge as a nitrogen substitute significantly increased the soil organic carbon at the jointing stage and reached a 100% replacement ratio at the maturity stage. During the jointing and mature stages, the total nitrogen content of the soil increased significantly at the 100% replacement ratio, while the soil nitrate nitrogen content only increased significantly at the 50% and 100% replacement ratio. Our findings highlight the impact of sludge compost on greenhouse gas emissions and soil nitrogen and guide the use of sludge compost in wheat fields.