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Research on the Effect of Conservation Tillage Mode on the Suppression of Near-Surface Dust in Farmland

In order to explore the beneficial effects of conservation tillage (straw burial, stubble + straw mulching, straw mulching) compared with traditional tillage on suppressing farmland dust and the law on farmland wind erosion, PM2.5 and PM10, in this study, according to the distribution characteristics of farmland dust particles “from large to small” and “from bottom to top”, the self-designed dust collector and farmland dust online monitoring system were used to analyze the amount of wind and dust, PM2.5 and PM10, near the surface of farmland. A comparative study on the dust emission of farmland from conservation tillage and traditional tillage is conducted in two dimensions. The mobile wind tunnels are used to simulate and verify the release of PM2.5 and PM10 near the surface of farmland. Among them, the monitoring of farmland wind erosion shows that compared with traditional farming, the wind erosion of straw burial, stubble + straw mulching, and straw mulching decreased by 29.37%, 40.73%, and 36.61%, respectively, and 90~250 μm large-size sand particles are reduced by 37.2%, 74.7%, and 31.6%, respectively. The monitoring results of PM2.5 and PM10 near the surface of the farmland showed that the stubble + straw mulching model is compared with the traditional farming farmland. The reductions were 42.5% and 40.8%, significantly higher than the straw burial and straw mulching modes. The multiple linear regression analysis of the monitoring data showed that the PM2.5 and PM10 release concentrations near the surface of farmland had the highest correlation with wind speed, followed by soil moisture and temperature. Wind tunnel test verification shows that the following three protective tillage modes: straw burial, straw mulching, and stubble + straw mulching, have apparent inhibitory effects on PM2.5 and PM10 released on farmland compared with traditional tillage modes. In 1~8 m/s interval, the release concentration of PM2.5 in the modes of straw burial, stubble + straw mulching, and straw mulching decreased by 15.34~41.17%, 32.05~48.56%, and 28.85~42.40%, and the PM10 release concentration decreased by 19.44~36.47%, 35.90~52.00%, and 25.83~50.63%, respectively, which are consistent with the monitoring results of PM2.5 and PM10 near the surface of farmland. The research results show that the beneficial effects of each model on farmland dust suppression are stubble + straw mulching > straw mulching > straw burial. The study is intended to provide theoretical support for promoting conservation tillage and the return of high-quality straw mulch to the field in Beijing.