旋耕抛-导土式膜上覆土关键技术与抗旱稻覆膜旱直播机研究

Rotary-till Soil-casting Key Technology for Above-film Soil Cover and Development of Film-mulching Dry Direct-seeder for Drought-resistant Rice

摘要:

针对抗旱稻旱直播覆土机具结构复杂、膜上覆土层厚度和覆土率变化较大等问题，在土槽试验探明旋耕抛土的运动规律基础上，将旋耕、铺膜、覆土多环节协调设计，提出并完善旋耕抛-导土式膜上覆土技术模式，并以此关键技术研究抗旱稻覆膜旱直播机。在理论分析建立正转旋耕土壤运动及其抛-导土运动学模型基础上，明确影响覆土性能的导土板关键设计参数，将单因素试验与理论计算相结合，明确了导土板相对旋耕刀回转中心、地面的空间位置和水平安装角度3个关键设计参数的取值范围。进而以膜上覆土率、膜上覆土层厚度变异系数为评价指标，开展三因素三水平正交土槽试验，基于所得覆土作业结果并利用响应面分析获得多目标约束条件下的最佳参数组合，探明旋耕抛-导土关键技术并将其应用于抗旱稻覆膜旱直播机设计中，最后开展田间试验验证整机性能。试验结果表明：所提出的旋耕抛-导土关键技术的3个设计参数对膜上覆土性能有显著影响；最佳参数组合：导土板水平安装角度为38°，导土板下端离地距离为111mm，导土板下端与旋耕刀回转中心水平距离为362mm。对应最优设计参数可实现膜上覆土率94.2%，膜上覆土层厚度变异系数14.8%，在田间验证试验中，对应性能指标最佳数据为：膜上覆土率94.5%，膜上覆土层厚度变异系数14.8%，符合预期。旋耕抛-导土关键技术以表土50mm浅旋、高转速500r/min为基本特征，实现切土高抛、铺膜装置越顶式的膜上覆土目标，导土板关键设计参数研究结果可为抗旱稻覆膜直播覆土装置参数优化提供参考。

Abstract:

Mechanized production of dry direct-seeded and degradable film-mulched draught-resistant rice is challenged by the complexity of the seeding implements, the difficult control of mulched soil layers above the film, and the large deviation of soil thickness. A soil-bin investigation was conducted to illustrate soil movement induced by rotary till. Based on the recognized characteristic of soil movement, compromised design of rotary till, film application and soil mulching mechanisms was made to formulize the rotary-till soil-casting technology, which was further adapted to the development of a film-mulching dry direct-seeder for draught-resistant rice. Soil movement induced by rotary-till was theoretically investigated to formulize the model of soil casting and redirecting. Key parameters of the soil-redirecting plate were identified and single-parameter experiment was made on each parameters. The results from both the experiment and theoretical analysis clarified the selective ranges of the three parameters, i.e., dimensions of the soil-redirecting plate respecting to both the rotary blade rotation center and the ground level. By introducing the above-film soil covering rate and variation of the soil layer as criteria, orthogonal experiment of three factors in three levels was followed to illustrate the optimum combination of the three influencing factors. The rotary-till soil-casting technology was clarified and was then adapted to the development of a film-mulching dry direct-seeder for draught-resistant rice. Field test was then conducted to evaluate the performance of the developed seeder. Results showed that the proposed three parameters had significant influence on the performance of rotary-till soil-casting technology. The optimum combination of the design parameters were 38° for the tilting angle of the plate, 111mm of height of the plate and 362mm from the plate to the rotary blade rotation center. Such a combined set of parameters yielded the best performance of 94.2% soil covering rate and 14.8% of soil thickness variation in soil bin test. While in the field evaluation they were 94.5% and 14.8%, respectively. Rotary-till soil-casting technology was featured by 50mm shallow soil engaging and 500r/min high speed rotating, which achieved the purposes of soil-cutting and high casting, overtopping the film-applying mechanisms and soil mulching on the applied film. The findings of parameterized design of soil-redirecting plate in this work can be applied as a reference for related research in the future.