退化羊草地切根释压松土工艺研究与试验

Research and Experiment on Loosening Soil by Cutting Roots to Release Pressure for Degraded Leymus chinensis Grassland

摘要:

以羊草等根茎型或根茎疏丛型牧草为建群种的天然草地退化状况严重，机械化松土是改良这类草地的重要手段之一，但不恰当的松土方式极易破坏草地植被，并导致土壤沙化。为探讨适宜改良退化羊草地的松土方式，提出了一种切根释压松土方法。以海拉尔地区的退化草地为研究对象，采用离散元仿真与田间试验结合的方式开展了传统松土、对缝松土和切根释压松土对比试验，分析3种松土方式对草地的扰动过程、作业质量及松土阻力的影响。仿真结果表明：切根释压松土比传统松土和对缝松土对土壤的疏松效果更好，提高了深层土壤流动性并降低了表层土壤扰动。将仿真结果与田间试验结果对比，结果表明3种松土方式作业后的耕作部件松土阻力变化趋势一致。切根释压松土方式松土阻力最小，仿真结果为3692.75N，田间试验结果为4677.84N。传统松土方式松土阻力最大，仿真结果为5348.80N，田间试验结果为6489.40N。对缝松土方式松土阻力介于两者之间，仿真结果为4713.33N，田间试验结果为5433.24N。这表明切根释压松土方式具有较好的减阻效果。田间试验结果表明，松土方式对作业质量具有显著性影响。相同耕作深度土层内，切根释压松土方式相较传统松土和对缝松土作业后的土壤坚实度均值分别降低6.19%和12.67%，土壤容重均值分别降低1.19%和3.16%。同时切根释压松土方式对表层土壤扰动最小，土壤疏松效果更好，作业后的土壤扰动系数和土壤蓬松度均值分别为49.05%和25.81%。研究结果可为改进退化羊草地松土工艺，优化设计草地松土改良机具提供依据。

Abstract:

Natural grasslands with rhizome-type or rhizome-sparse grasses such as Leymus chinensis as the established species are in serious degradation. Mechanical soil loosening is one of the important means to improve this type of grassland. However, inappropriate methods of soil loosening can easily damage the grassland vegetation, and lead to soil desertification. In order to explore the suitable soil scarification method for improving degraded Leymus chinensis grassland, a method of loosening the soil by cutting roots to release pressure was proposed. Taking the degraded grassland in Hailar area as the research object, a comparative test of traditional loosening, loosening the soil along the cracks, and loosening the soil by cutting roots to release pressure was carried out by using a combination of discrete element simulation and field test. The effects of three loosening methods on the grassland disturbance process, work quality and loosening resistance were analyzed. The simulation results showed that loosening the soil by cutting roots to release pressure had a better loosening effect on the soil than traditional loosening and loosening the soil along the cracks. It improved the fluidity of the inner soil and reduced the disturbance of surface soil. Comparing the simulation results with field test, the results showed that the change trend of the loosening resistance of the tillage parts after the three loosening methods were consistent. The method of loosening the soil by cutting roots to release pressure had the smallest soil loosening resistance, the simulation result was 3692.75N, and the field test result was 4677.84N. The traditional loosening method had the highest loosening resistance, the simulation result was 5348.80N, and the field test result was 6489.40N. The loosening resistance of the method of loosening the soil along the cracks was between the two, the simulation result was 4713.33N, and the field test result was 5433.24N. The results showed that loosening soil by cutting roots to release pressure method had a better drag reduction effect. Field test results showed that soil loosening methods had a significant impact on work quality. In the soil layer with the same tillage depth, by comparing the traditional loosening and loosening the soil along the cracks, the soil compactness after loosening the soil by cutting roots to release pressure was decreased by 6.19% and 12.67%, respectively, and the mean soil bulk density was decreased by 1.19% and 3.16%, respectively. At the same time, loosening the soil by cutting roots to release pressure method caused the least disturbance to the surface soil and had a better soil loosening effect. The average values of the soil disturbance coefficient and soil bulkiness after the operation were 49.05% and 25.81%, respectively. The research results can provide an important basis for proposing soil scarification improvement technology for degraded Leymus chinensis grassland and optimizing the design of grassland scarification improvement equipment.