RESUMO
It is well recognized that straw return (SR) can improve soil fertility and soil organic carbon (SOC) storage. Increasing planting density and reducing nitrogen fertilizer application is considered an effective cultivation technique for japonica rice in central and northern China. However, few are known about the mechanisms of differences between wheat SR with rice planting densification and N reduction (SRD) and wheat SR on greenhouse gas emissions and soil bacteria communities in central China. A 2-year experiment was conducted to evaluate the effects of SR and SRD compared with straw removal (NS) on methane (CH4) and nitrous oxide (N2O) emission, rice yield, and soil properties in Henan Province, China, in 2019 and 2020. We found that SRD increased SOC, available phosphorous (AP), and available potassium (AK) compared to SR and NS in 2019 and 2020. The mean CH4 flux was positively correlated with SOC, and the cumulative CH4 emissions of SR and SRD plots were significantly higher than those of NS plots. No significant difference in cumulative CH4 emissions was detected between the SR and SRD treatments. N2O emissions were significantly lower under SRD than SR. SRD significantly affected soil bacteria diversity and composition at a depth of 0-15 cm. The relative abundance of Bacteroidota in SRD soil was 1.37- and 3.73-fold higher than that in NS and SR soils, respectively. The relative abundance of nitrate reduction-related operational taxonomic units enriched under SRD was significantly lower than that under SR, indicating that lower nitrate reduction of N2O production was induced by soil bacteria under SRD. N partial factor productivity was 21.4% and 28.5% higher under SRD than SR in 2019 and 2020, respectively. Our results suggest that SRD decreased soil bacteria N2O emissions; increased SOC, AP, and AK; and improved N fertilizer use efficiency, thereby improving rice yield in central China.
