Effects of Rice Straw Return on Soil Labile Organic Carbon and β-Glucosidase Activity in Paddy Soil

Abstract

Rice straw is a source of organic matter (OM) that improves soil fertility. After rice straw is returned to the soil, increased microbial enzyme activity decomposes organic residues, affecting soil carbon. To evaluate the effects of continuous rice straw return on soil labile organic carbon (LOC) fraction and β-glucosidase (BG) activity in paddy soil, an experiment was conducted with four treatments; Chemical fertilizer treatment (NPK), Chemical fertilizer + rice straw treatment (NPKR), Green manure treatment (GM) and Green manure + rice straw treatment (GMR). Hot water extractable carbon (HWEC) content, permanganate oxidizable carbon (POXC) content, and BG activity were analyzed. HWEC content was 42% higher than in NPKR than in NPK. It was 8% higher in GMR than in GM, but there was no significant difference. In addition, POXC content was 17% higher in NPKR than in NPK. It was 11% higher than in GMR than in GM, but there was no significant difference. BG activity was 36% higher in NPKR than NPK, and 55% higher in GMR than GM. As a result, in paddy soil that are low in OM due to the predominant use of chemical fertilizers, rice straw return is likely to increase OM supply and LOC content in the soil and contribute to carbon cycling.