Soil decreases N2O emission and increases TN content during combined composting of wheat straw and cow manure by inhibiting denitrification

Nitrogen loss is a significant factor limiting the quality of compost products. This work examined the composting of cattle manure and wheat straw in combination with soil quantifying composting performance, microbial communities and nitrogen metabolism. Compost combined with lou soil (LS), gray desert soil (GDS) and acidic purple soil (APS) had increased in total nitrogen content of 74.4, 39.0 and 48.1 %, respectively, surpassing the control (CK) by at least 24.5 %. In comparison to CK (207 mg/kg), the LS, GDS and APS treatments had N2O emissions lowered by 15.7, 13.2 and 3.5 %, respectively. These results show that LS and GDS additions can effectively lower greenhouse gas emissions and nitrogen loss. The addition of these soils also enriched specific ammonification bacteria, thereby facilitating nitrogen metabolism throughout the composting process. With LS, the relative abundances of ammonification bacteria, such as Corynebacterium and Ureibacillus, increased by 156 and 141 %, respectively, whereas with GDS, the increases were 108 and 133 %, respectively. Also, the addition of LS and GDS decreased nitrogen loss during composting by increasing the enrichment of nitrification genes and decreasing the enrichment of denitrification genes (norB and norC) to a certain extent. This work provides a novel, cost-effective and sustainable technique for enhancing composting, as well as valuable insights into the critical function of different soil-mediation in reducing nitrogen loss and greenhouse gas emissions during composting.