Effect of NH4+ and NO3- cooperatively regulated carbon to nitrogen ratio on organic nitrogen fractions during rice straw composting

Abstract

The purpose of this study was to examine the effects of replacing urea with inorganic nitrogen on the organic nitrogen sequestration process and the mitigation of nitrogen loss during rice straw composting. These groups include a control group with urea addition (CK), a group with (NH₄)₂SO₄ addition (NH), a group with KNO₃ addition (NO), and a group with (NH₄)₂SO₄ + KNO₃ addition (NN). The results demonstrated that adding NH, NO, and NN significantly increased the content of bioavailable organic nitrogen in the composting. Furthermore, compared to the CK, the NH treatment reduced nitrogen loss by 8.41 %. Structural equation modeling revealed the correlation between bacterial communities and organic nitrogen fractions in different treatment groups. Comparisons of nitrogen efficacy and nitrogen loss indicated that adding (NH₄)₂SO₄ was more effective during composting, which provided a meaningful research basis for rice straw composting.

Keywords: C/N ratio; Composting; Inorganic nitrogen; Microorganism; Organic nitrogen.