Modeling of soil-tool interaction in material incorporation

有机物质进入土壤具有显著的环境效益，土壤肥力和土壤侵蚀保护。本研究的目标是开发一种独特而通用的方法来设计土壤啮合工具（清扫器，圆盘，开启器，滚动时间等），以便有效地将有机材料（如牲畜粪便和作物残留物）纳入农业土壤中。现有土壤接触工具存在的问题包括保护性耕作系统中作物残茬的砍伐、草料和免耕系统对土壤的高干扰以及作业对能源的高需求。在世界粮食需求、能源成本和环境影响成为现实的时候，迫切需要振兴土壤参与工具的设计，以提高其效率和效果。土壤吸附工具的性能在很大程度上取决于它如何与土壤和它们所处理的有机物质相互作用。目前，商业土壤吸附工具的设计仍然依赖于传统的土壤-工具相互作用模型，即土壤行为和土壤-工具相互作用。在大多数传统模型中，使用有限元方法（FEM）并将土壤视为连续弹塑性介质，然而，土壤表现为不连续介质，并且在工具周围作为单个颗粒（集合体和土块）流动。因此，有限元法不能完全模拟农业土壤和土壤-工具在颗粒水平上的相互作用。此外，FEM无法处理不同材料在“颗粒”水平上的混合物，例如混合作物残渣“颗粒”与土壤“颗粒”。长期以来，有限元法的这些缺陷限制了土啮合工具的设计。离散元法（DEM）允许将土壤建模为集料/土块的集合，并处理在材料合并中遇到的多种颗粒。DEM在土壤动力学中的应用是一个新兴的研究领域，目前还处于起步阶段。拟议的研究将在推进该领域迈出重要的一步，利用申请人实验室可用的专业知识和研究工具，加拿大最后一个功能齐全的土壤动力学实验室。

Incorporation of organic materials into soil has significant benefits to the environment, soil fertility, and soil erosion protection. The goal of this research is to develop a unique and universal approach to design soil engaging tools (sweeps, discs, openers, rolling tines, etc.) for efficient incorporation of organic materials (such as livestock manure and crop residue) into soil in agriculture. Problems associated with the existing soil engaging tools include logging of crop residue in conservation tillage systems, high soil disturbance in forage and no-till systems, and high requirement of energy for operations. At a time when world food demand, cost of energy, and environmental impact are a matter of fact, it becomes urgent to rejuvenate soil engaging tools design to improve their efficiency and effectiveness. The performance of a soil engaging tool highly depends on how it interacts with soil and the organic materials they deal with. Currently, the design of commercial soil engaging tools still rely on the traditional soil-tool interaction models on soil behaviour and soil-tool interactions. In most traditional models, the Finite Element Method (FEM) was used and soil is considered as a continuous elastic-plastic media, whereas, soil behaves as a discontinuous media and flows as individual particles (aggregates and clods) around the tool. Thus the FEM is not fully capable to model agricultural soil and soil-tool interactions at the particle levels. Also, the FEM is not able to deal with a mixture of different materials at the "particles" levels, such as mixing crop residue "particles" with soil "particles". These incapacities of FEM have limited soil engaging tool design for ages. The Discrete Element Method (DEM) allows to model soil as an assembly of aggregates/clods and deal with more than one types of particles encountered in material incorporations. Using the DEM in soil dynamics is an emerging field, and this field is at its infancy stage. The proposed research will take a significant step in advancing the field, with the available expertise and research tools in the applicant' lab, the last soil dynamics lab in Canada which is fully functional.