Effects of straw return on soil carbon sequestration, soil nutrients and rice yield of in acidic farmland soil of Southern China

Straw return was extensively applied owing to its multiple positive impacts on improving soil fertility, impeding soil degradation, enhancing soil carbon sequestration and increasing crop yield. Yet, the understanding of effects of straw return on carbon sequestration, soil nutrients, and rice yield of farmland with acidic soil at large spatial scale still largely remains unclear in farmland soil of Southern China. Most of previous studies focused on field scale and local regions using limited data collected from local surveys, while evidence from extensive dataset at large spatial scale are rarely reported. Therefore, this study aims to comprehensively analyse the effects of straw return on soil carbon sequestrations, soil nutrients, and rice yield. Here 15,780 topsoil samples were collected from farmland across the Jiangxi Province in Southern China, which is a region seriously affected by soil acidification due to overuse of chemical fertilizer, acidic rainfall, geology and climate characteristics. And the one-way ANOVA analysis and SEM analysis was conducted to examine the impact of straw return on soil carbon sequestration, soil nutrients and rice yield in farmland of Jiangxi Province, and tested whether the impact are statistically significant. The results indicate the soil organic carbon density (SOCD) increased by 71.15% by returning straw. Additionally, straw return significantly improved available nitrogen (N), total N, quick-acting potassium (K), total K, available boron, iron, and sulphur by 21.10, 63.03, 3.90, 6.34, 10.24, 8.82, and 12.87%, respectively. The rice yield significantly improved with the increase of amount of straw returned. The rice yield via overturn and return to the field (12,742.76 kg ha(-1)) was significantly higher than farmland via cover and return to field (7111.16 kg ha(-1)) and farmland without straw return (11,691.94 kg ha(-1)). However, straw return may exacerbate soil acidification since this study found soil pH significantly (p < 0.001) decreased with increase of the amount of straw returned, which is particularly noteworthy in areas like this survey region that are plagued by soil acidification. The results obtained in this study confirmed that straw return is an environment-friendly, highly efficient, and cost-effective way to reduce the usage of chemical fertiliser accompanied by improving soil fertility, soil carbon sequestration, and crop yield.a