Erodibility of claypan soils: Identifying erosion mechanisms for sustainable reduction of sediment loss

1705823(萨森拉特)。粘土层在美国占地约400万公顷，其特点是表层下有一层高度不透水的土层。这种不透水层可能会在土壤基质中产生侧向流动，从而增加表层土壤的侵蚀速度。表层植被增加了粘性土表层的抗侵蚀能力，但有限的表土层却在逐年减少。这项研究的目的是在表层土壤不可挽回地丧失之前，找出造成泥沙流失的机制，并恢复土壤和水生态系统的生态功能。目的是检验不透水粘土层通过破坏表层土壤而增加土壤侵蚀的假设。这将通过测量来自土壤管理做法相同但土壤流失可变的地区的土壤样本的可蚀性和强度来实现。通过航空图像、地形分析、产量图和表面电导率测量确定了这种可变性。将使用各种岩土技术方法来测量可蚀性的岩土分界，包括实验室中的侵蚀函数装置和现场的喷射侵蚀试验。这项研究的主要假设是，表土正在遭受土心内部的侵蚀，这进一步降低了它的抗剪强度，从而增加了可蚀性。测量的强度和侵蚀参数将被用来更好地预测泥沙流失。该研究计划是与当地土地所有者密切合作制定的。将与土地所有者分享对造成粘土层可蚀性现象的基本机制的理解，以便制定和实施适当的土地利用管理做法。由一名农学家、一名岩土工程师和一名大众传播专家组成的多学科领导团队将与推广人员、自然资源保护者和土地所有者密切合作，解决这一多方面的问题并实施变革。

1705823 (Sassenrath). Claypan soils cover approximately 4 million hectares in the US and are characterized by a highly impermeable layer below the topsoil. This impermeable layer may create lateral flow within the soil matrix that increases the rate of erosion of the topsoil. Surface vegetation increases the erosion resistance at the surface of claypan soils; however, the limited topsoil continues to diminish annually. This research addresses the need to identify the mechanisms that are causing this sediment loss and restore the ecological function of soil and water ecosystems before the topsoil is irretrievably lost.The objective is to test the hypothesis that the impermeable claypan layer is increasing soil erosion by undermining topsoil. This will be achieved by measuring the erodibility and strength of soil samples from areas where soil management practices are identical yet soil loss is variable. The variability has been identified by aerial imagery, terrain analysis, yield maps and surface conductivity measurements. Geotechnical delineation of erodibility will be measured using a variety of geotechnical methodologies, including an Erosion Function Apparatus in the laboratory and a Jet Erosion Test in the field. The primary hypothesis of this research is that topsoil is undergoing undermining erosion within the soil core which is further reducing its shear strength and thus increasing the erodibility. Measured strength and erosion parameters will be used to better predict sediment loss. The research plan has been developed in close collaboration with local landowners. The understanding of the fundamental mechanisms that are resulting in the claypan erodibility phenomena will be shared with landowners so appropriate land use management practices can be developed and implemented. The multidisciplinary leadership team of an agronomist, a geotechnical engineer, and a mass communications specialist will work closely with Extension personnel, conservationists and landowners to address this multifaceted problem and implement change.