Collaborative Research: Root Induced Changes of Soil Physical Properties Using Synchrotron X-ray Microtomography (CMT) and Micromechanical Simulations

根际，即植物根系周围的土壤区域，在向植物提供水分和养分方面起着重要作用。然而，令人惊讶的是，人们对根际物理特性以及它们如何影响根系生长、水分和养分吸收知之甚少。缺乏非侵入性和非破坏性的成像技术来观察在未受干扰的土壤中生长的活根是造成这一缺点的主要原因。同步加速器x射线微断层扫描技术（CMT）的最新进展，提供了直接观察活根周围土壤物理特性的潜力。本研究的目标是通过(1)利用CMT可视化根-土结构物理相互作用，(2)利用计算机模型利用微力学方法模拟根引起的根际结构变化，以及(3)基于CMT成像和逆建模估计根际水力特性的变化，如保水性和导电性。本研究旨在为根际物理特性对活植物吸收水分和养分的作用提供变革性的见解。它为更好地理解植物在土壤-大气界面关键区域的作用提供了一个敲门砖。该项目跨越了生物学、土壤物理学和土壤力学的学科界限，为地表径流、土壤压实和侵蚀、农业生产力损失、土地复垦和土壤-植物相互作用原理提供了新的见解。通过本项目培养博士研究生和博士后1人。

The rhizosphere, the zone of soil immediately surrounding plant roots, plays a prominent role in supplying plants with water and nutrients. However, surprisingly little is known about rhizosphere physical properties and how they affect root growth, water and nutrient uptake. The lack of non-invasive and non-destructive imaging techniques necessary to observe living roots growing in undisturbed soil have been a main reason for this shortcoming. Recent advances in synchrotron X-ray microtomography, or CMT, provide the potential to directly observe soil physical properties around living roots in-situ. The goal of this research is to quantify rhizosphere physical properties by (1) employing CMT to visualize physical root-soil structure interactions, (2) using computer models to simulate root-induced structural alterations to the rhizosphere using micro-mechanical approaches, and (3) estimating changes in rhizosphere hydraulic properties, such as water retention and hydraulic conductivity, based on CMT imaging and inverse modeling.This research seeks to provide transformative insights into the role of rhizosphere physical properties for water and nutrient uptake by living plants. It serves as a stepping stone for better understanding the role of plants in the critical zone at the soil-atmosphere interface. The project cuts across disciplinary boundaries of biology, soil physics, and soil mechanics to offer new insights on surface runoff, soil compaction and erosion, losses to agricultural productivity, land reclamation, and principles of soil-plant interactions. Doctoral students and a post-Doctoral associate will be trained through this project.