正反转旋耕作业的秸秆混埋效果比较

秸秆混埋是增强土壤碳汇的重要技术途经。为分析和比较正、反转旋耕作业的秸秆混埋效果,进行了正、反转旋耕秸秆混埋对比试验。测取旋耕处理后的地貌形态及秸秆在土壤空间中的分布状况,并使用Pro-E造型展示秸秆的空间分布状况。结果表明三维数字化仪配合虚拟造型技术能够直观反映混埋后秸秆在土壤空间的分布状态。2种旋耕处理方式的地表形态及土壤空间内秸秆分布对比分析表明,正转旋耕的秸秆埋覆率及纵向空间分布总体均匀率优于反转旋耕,而反转旋耕的秸秆在沿土壤深度方向的空间分布均匀率、秸秆-土壤混合效果、耕幅内地表平整度等优于正转旋耕。综合分析表明正转旋耕的秸秆混埋质量略有优势,但具体选择混埋模式时还应考虑田间秸秆残留情况。秸秆量较少时反转旋耕较适宜,反之正转旋耕更好。

Comparison of straw incorporation effect with down-cut and up-cut rotary tillage

Abstract: Due to the complexity of soil and straw properties and the interactions among soil, straw and tillage tools, specific straw incorporating implements were designed and developed for particular working conditions. Different types of rotary tillers that adapted to different field states were produced in the last decades for straw burial. However, past efforts of assessment on rotary tillers were focused mainly on their soil working performances. Seldom has been done to assess the performance of rotary tillers and their effect on both soil disturbance and straw distribution in the tilled soil layer. A field experiment was thus conducted to compare the performances of rotary tillers on mediating soil and straw after rice harvesting. A mini-power rotor tiller was run on a platform developed for in-situ tillage test. Soil surface and micro-relief was measured with profilometer. Straw distribution was measured with a three-dimension coordinate tester. The measured results were transferred to Pro-E software, in which the measured data of straw distribution in soil were modeled and assessed. It was found that down-cut rotary tillage resulted into a gently humped soil surface over the tilled region, whereas the up-cut treatment led to a sink of soil surface in the mid region and the ridges along two sides of the tilled plot. Severe humping of fragmented soil was also observed in the up-cut tillage. It was therefore concluded that, for min-power rotor tillers in paddy field, the down-cut tillage provided better surface micro-relief than the up-cut. A higher percentage of buried straw, 88.91%, was acquired with the down-cut tilling. But it was low for the up-cut, which was 83.26%. The heaping-up of straw was also severe in the up-cut treatment, which was 33.02%, 8.19% higher than that from the down-cut. This indicated that the down-cut was more preferable for mini-power rotor tiller design compared with the up-cut. Analysis on the sectioned regions with the Pro-E revealed more straw concentration in the 5-10 cm soil layer for the down-cut tillage, while the up-cut treatment provided a more evenly distribution of straw in the soil volume. The modeled straw distribution in soil volume was sectioned into the grids at 3 different scales, and the total length of straw under the down-cut tillage revealed the smaller coefficient of variations (P<0.05). The up-cut tilling did prove its benefits, such as enhancing soil fragmentation and a highly leveled soil surface within the treated area. But the soil and straw heaping ahead of the machine was a main constraint for its adaptation to the paddy soil. Designing and developing of mini-rotor tillers for improving the performance of proper handling the soil and straw requires further investigation on the system optimization of soil structure, straw, tool geometry and working parameters.