西北旱区马铃薯机械化全膜覆土栽培促生机理及跨越式膜顶覆土作业方法研究

In order to solve the problems of releasing seedlings and dibbling artificially in potato mulching film cultivation in the northwest arid area, the project intends to apply growth-promoting mechanism covering soil on film in potato high-yielding cultural techniques with mulching film on whole area. It aims to break through covering soil on film mechanically and achieve the mechanization in the process of potato mulch sowing. The mechanical properties and physiological characteristics of potato plumule under different environmental factors will be explored to clarify the response mechanism of high temperature and stress resistance and ascertain the variation regulation of plumule penetration resistance and emergence time, analyze the growth-promoting mechanism from the perspective of crop growth mechanics, so as to provide the basis for constructing the film-soil mulching system, which is suitable for potato plumule puncturing and emerging. The operating principle and soil transport characteristics of the spanning model covering soil equipment will be analyzed based on the mechanical soil dynamics theory. Using the software of EDEM, the property of covering soil in different gradient conditions of loess hilly and gully region will be researched to explore the soil band’s deviation principle and the way to eliminate it. And then, the variation regulation of covering soil’s quality in different structure and working parameter will be clarified. According to optimizing the device’s structure, a series of design method of covering soil machine will be invented in the developing of new potato planter. The research can expand the connotation of biological solid mechanics, enrich the theory of plant anti-reversibility cultivation, and improve the level of the design theory of the mulching film planting machine.

针对西北旱区马铃薯覆膜栽培中人工放苗和打穴播种机械替代难的问题，本项目拟将马铃薯膜顶坐土促生机理应用于地膜全域覆盖高产栽培技术，突破机械化膜顶覆土难题，以期实现马铃薯覆膜播种全过程机械化。通过研究马铃薯幼芽力学特性、生理特征在不同环境因素作用下的变化，阐明其对高温、应力胁迫的响应机制，探明幼芽穿透阻力及破膜时间的变化规律，从作物生长力学角度解析马铃薯膜顶坐土促生机理，为构建适宜幼芽破膜出苗的膜土覆盖系统提供依据；根据机械土壤动力学理论分析跨越式膜顶覆土装置取土原理及输土特性，基于EDEM研究该装置在黄土丘陵沟壑区不同坡度条件下的覆土特性，探索苗带与覆土条带错位原理与消除方法，研究不同结构、作业参数下覆土合格率的变化规律，优化覆土装置结构，提出一套膜顶覆土机具设计方法，开发新型马铃薯全膜对行覆土种植机。该研究可拓展生物固体力学内涵，丰富植物抗逆栽培理论，提升覆膜种植装备设计理论水平。

针对西北旱区马铃薯覆膜栽培中人工放苗和打穴播种机械替代难的问题，本项从作物生长力学角度解析了马铃薯膜顶坐土促生机理，构建了机械化轻简化生产技术模式，突破了机械化对行覆土难题，开发了配套种植机具。利用显式动力学分析软件LS-DYNA模拟了不同厚度土壤覆盖对马铃薯幼茎自动破膜能力的影响。结果表明，当覆膜厚度在0～20mm之间时，破膜时间逐渐缩短，幼苗的生长阻力逐渐增大。当覆盖土壤厚度在20mm至70mm之间时，破膜时间和幼苗生长阻力的变化不太显著，在40mm左右时，生长阻力显著降低。借助fluent软件构建了马铃薯垄体、太阳、大气辐射对流传热系统模型，模拟马铃薯垄体传热动态响应过程，监测马铃薯垄体温度场分布特点。结果表明，马铃薯垄体不同土层处温度日变化近似正弦曲线，且随着土层深度的增加，温度振幅变小，温度峰值和谷值出现延迟；覆土厚度、覆土宽度的增加均可降低马铃薯垄体各层温度振幅，选取覆土宽度为200mm、覆土厚度为40mm。针对膜顶坐土促生机理确定的覆土要求，优化了跨越式膜上覆土装置。田间覆土特性试验表明：刮土板速度与作业速度比由1.38增至2.56，输土量减小；刮土板间距、输送带倾角分别由100mm增至140mm、35°增至55°，输土量减小，输送效率降低；刮土板高度由40mm增至60mm，输土量增加，输送效率降低。参数限制区间内，最优参数组合为刮板速度与作业速度比1.38，刮土板间距100mm，刮土板高度60mm，输送带倾角35°。在上述研究基础上，设计了马铃薯施肥播种起垄全膜覆盖种行覆土一体机，对样机关键部件进行了分析与设计。田间试验表明，播种深度合格率为86%，种薯间距合格指数为89%，重种指数为5%，种行覆土宽度合格率为92%，种行覆土厚度合格率为94%，邻接行距合格率为86%。田间性能试验指标均达到国家和行业标准要求，该机能够实现施肥、播种、起垄、全膜覆盖、种行覆土一体化作业，满足西北旱区马铃薯覆膜栽培农艺要求。该研究为西北黄土高原旱作农业区构建高产、高效的机械化马铃薯栽培技术体系提供了理论和实践依据。

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