| Tillage erosion has become an important factor restricting the ecological environment improvement and maintenance of purple soil.In view of the characteristics of low threshold ecological security and high risk ecological degradation of purple soil, the magnetic tracer was used to label experimental plots of soil to analysis the tillage erosion characteristics and its main influencing factors of different tillage tools.Then, combined with the simulated tillage to test the effects of different tillage tools and tillage practices on soil profile properties and micro landform evolution, in order to explore the conservation tillage technology, which adapt to local conditions of purple soil.The tillage erosion caused by three kinds of conventional tillage in the purple soil area of Sichuan Province increased in the order:downslope hoeing>contour plowing>rotary up-downslope tillage. The tillage tillage erosion rates by rotary up-downslope tillage compared to the downslope hoeing and contour plowing reduced by 88% and71%. Starting from the angle of the tillage erosion control, rotary up-downslope tillage is the best choice in three kinds of conventional tillage.Under different tillage tools and different tillage directions, the tillage erosion intensity increased in the order: downslope hoeing>contour hoeing,downslope plowing>upslope plowing>contour plowing>up-downslope plowing, rotary contour tillage>rotary up-downslope tillage. Tillage erosion intensity markedly enhanced by adding tillage depth. Tillage erosion rates induced by up-downslope alternative tillage were less than those by contour tillage at high gearoperation; however, the two was equivalent at low gear operation.Compared with wide-hoe, the tillage erosion rates caused by narrow-hoe, perforated-hoe and bidentate-hoe were respectively reduced by 12.4%, 11.0% and 16.3%, which indicating that hoe form reform weakened the soil to downslope migration and leading to hoe tillage erosion decreased significantly. There is a strong correlation between the mechanical properties and physical properties of soil with tillage erosion.Tillage simulation experiments indicate a significant difference in the depth of soil profiles at the 0, 5, and 20 m positions between pre-tillage and 15-operation tillage(P<0.05), while there is no significant difference in the 10 and 15 m positions(P>0.05). After intense tillage, the soil profile disappeared on the slope summit due to intense soil downslope translocation, while a thickened soil profile was present in toeslope positions, where the original soil profile was buried. Thickness of soil layer at the summit position after Long-term contour plowingdecreased by32.6% and at the toeslope positions increased by 25.1%. The soil loss significantly, but does not lead to the bedrock exposured. Whether it is contour tillage or up-downslope tillage by the rotary cultivator will not cause the slope rock exposed,and has no significant effect on slope land elevation. Soil carbon and nitrogen phosphorus was completely depleted with the disappearance of soil profiles at the summit position, while a substantial increase in SOC inventories of the post-tillage soil profile was found in the toeslope position after the long-term tillage.Conservation technology of tillage erosion on the steep land of purple soil should be reasonably configured according to different slope ranges. Up-downslope alternative plowing was suitable forgentle slope from 0 to 5 degrees. Up-downslope alternative tillage by the rotary cultivator was suitable for moderate slope from 5 to 15 degree and steep slope from 15 to 25 degrees. When the slope is greater than 25 degrees, it is necessary to return farmland to forest. |
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