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Quantifying soil biomechanics using X-Ray diffraction-imaging and physical modelling

使用 X 射线衍射成像和物理建模量化土壤生物力学

基本信息

批准号：
BB/X010147/1
负责人：
Siul Ruiz
金额：
$ 41.95万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2023
资助国家：
英国
起止时间：
2023 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FX010147%2F1
关键词：
Quantifying soil biomechanics using Ray

项目摘要

Desertification caused by climate change and soil compaction caused by land use intensification are exacerbating social issues ranging from food security to civil development and are expected to worsen dramatically in the near future. Soil compaction from intensified farming affects 25-45% of Europe's arable land area. This results inincreased density, which makes soil's more rigid and harder to break. Similarly, as temperatures rise near the equator and droughts become more common, previously arable land will become deserts. As land becomes drier due to desertification, soils again become more brittle and rigid. This will have severe impacts on agriculture, which restrict soil penetration by growing plant roots and burrowing earthworms. These organisms are vital for crop and ecosystem health. As drier climates may pose a mechanical threat to food security, a better understanding of the fundamental factors that facilitate root growth becomes crucial. Few studies have investigated key physical constraints that shape below ground biological activity, the strategies these biological organisms employ in order to modify their own habitats, or the resulting impact that their modifications have on soil structural suitability. Understanding this biophysical interplay may harness greater potential to provide more sustainable farming and civil design practices. I propose to develop tools to assess the mechanical potential for soil to support biological activity that promotes agriculture under changing climates and land use practices.In order to move through soil, plant roots and earthworms must exert pressures that exceed the elastic limitations of soil to achieve deformations large enough for penetration. Under wetter conditions, inelastic soil deformation is ductile, and soil's resistance to penetration is lower. This facilitates biological movement below ground. However, as soil dries, capillarity pulls soil aggregates densely together and finer clay particles begin to bind tightly, which creates a more brittle and resistant body that hinders earthworm activity. Field compaction experiments have demonstrated that increased soil mechanical impedance also reduces crop yields. Despite the reduced efficacy of root growth under mechanically limiting conditions, studies have demonstrated that some plant roots still manage to exert pressures great enough to grow. A hypothesis for how roots achieve this is via multi-scale processes where root turgor pressure allows axial extension while cells near the tip multiply and reorient themselves acting to reduce local frictional effects and assemble past the root cap. While this ensemble of processes is suggested to allow some roots to locally exert up to 1 MPa of pressure (capable of fracturing chalk), there is no clear understanding as to how this growth mechanism can enable this magnitude of pressure nor at what scales these loads are actually being applied. Knowledge of these processes may unlock plant traits which can be harnessed to reclaim desertified land and maintain healthy soils in semi-arid regions.Besides being able to see below ground, X-ray techniques can also be used to determine physical forces acting on objects. To this end, I intend to couple X-ray techniques in order to measure and monitor below ground activity with mathematical models to interpret and quantify the forces they apply below ground. The results from my work will ultimately outline mechanical constraints that hinder biophysical activity as well as unveil key biophysical processes that facilitate plant growth under harsh climatic conditions. These considerations could be used to help remediate damaged land caused by climate change or land use intensification and better inform future agricultural practices.

气候变化造成的荒漠化和土地利用集约化造成的土壤压实正在加剧从粮食安全到民用发展等各种社会问题，预计在不久的将来将急剧恶化。集约化耕作造成的土壤压实影响了欧洲25%-45%的耕地面积。这会导致密度增加，使土壤变得更硬，更难破碎。同样，随着赤道附近气温上升和干旱变得更加普遍，以前的耕地将变成沙漠。随着土地因沙漠化而变得更加干燥，土壤再次变得更加脆弱和僵硬。这将对农业产生严重影响，农业通过种植植物根和挖蚯蚓来限制土壤渗透。这些生物对作物和生态系统的健康至关重要。由于较干燥的气候可能对粮食安全构成机械威胁，因此更好地了解促进根部生长的基本因素变得至关重要。很少有研究调查形成地下生物活动的关键物理限制，这些生物有机体为改变自己的栖息地而采用的策略，或者它们的改变对土壤结构适宜性的结果影响。了解这种生物物理相互作用可能会利用更大的潜力，提供更可持续的农业和民用设计实践。我建议开发工具来评估土壤的机械潜力，以支持在不断变化的气候和土地利用实践中促进农业的生物活动。为了在土壤中移动，植物根和蚯蚓必须施加超过土壤弹性极限的压力，才能获得足够大的变形，以便穿透。在较潮湿的条件下，非弹性土的变形是延性的，土的抗侵彻能力较低。这促进了地下的生物运动。然而，随着土壤的干燥，毛细作用将土壤团聚体紧密地拉在一起，更细的粘土颗粒开始紧密结合，这就产生了一个更脆弱、更具抵抗力的身体，从而阻碍了蚯蚓的活动。田间压实试验表明，土壤机械阻抗的增加也会降低作物产量。尽管在机械限制的条件下，根的生长效率会降低，但研究表明，一些植物的根仍然能够施加足够大的压力来生长。关于根是如何做到这一点的一个假说是通过多尺度的过程，其中根膨胀压力允许轴向伸展，而顶端附近的细胞繁殖并重新定位自己，以减少局部摩擦效应并聚集到根冠之外。虽然这一系列的过程被认为允许一些树根在局部施加高达1兆帕的压力(能够使白垩岩破裂)，但对于这种生长机制如何实现这种压力的大小，以及这些载荷实际施加的规模，还没有明确的理解。对这些过程的了解可能会揭示植物的特征，这些特征可以用来开垦沙化土地，并在半干旱地区保持健康的土壤。除了能够看到地下，X射线技术还可以用来确定作用在物体上的物理力。为此，我打算将X射线技术与数学模型结合起来，以便测量和监测地下活动，以解释和量化它们在地下施加的力。我的工作结果将最终勾勒出阻碍生物物理活动的机械约束，并揭示在恶劣气候条件下促进植物生长的关键生物物理过程。这些考虑可以用来帮助补救气候变化或土地利用集约化造成的受损土地，并更好地为未来的农业实践提供信息。