Abstract Biological soil crusts (biocrusts) are generally found in many landscapes. Biocrusts are known to have a key role in terms of soil stabilization but the mechanism of biocrusts is poorly understood. Thus, this work intends to examine the impact of two biocrusts: Cyanobacteria and Chlorophyte, on parameters of cohesive soil erodibility (erodibility coefficient, kd, and critical shear stress, τc) using a small-scale form of Jet Erosion Test (mini-JET) at different drying times. In addition, the study aims to develop relationships between τc and kd versus certain soil characteristics. Eighteen undisturbed soil samples of two biocrust types Cyanobacteria, and Chlorophyte, and bare soils were acquired from the banks of the Tigris River in Iraq, and were tested in a laboratory using a mini-JET at drying times of 5, 8, and 12 days, in order to mimic field conditions. It was observed that dead algae still adhered to and bound soil particles together throughout the observation period, which contributed to soil stability, and increased moisture and nutrient retention before decomposition. As the drying times increased in the two biocrusts, the statistical results showed a reduction in kd, while τc values increased. The kd decreased as salt concentration, organic matter, and calcium carbonate increased, while the τc increased. No change in pH levels of soil was observed due to the reactions in the biocrusts between the algal crust and soil particles, which increased organic matter and calcium carbonate. This study discusses the benefits of using a JET instrument; including reducing testing time, conserving energy, and providing low-cost method for observation of crusted soil stabilization, in comparison with previous techniques.

中文翻译：

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使用射流侵蚀试验研究由生物土壤结皮引起的土壤可蚀性参数的行为

摘要 生物土壤结皮（biocrusts）普遍存在于许多景观中。已知生物结皮在土壤稳定方面具有关键作用，但对生物结皮的机制知之甚少。因此，这项工作旨在使用小型喷射侵蚀试验（mini-JET）来检查两种生物结皮：蓝藻和叶绿体对粘性土壤可蚀性参数（可蚀性系数 kd 和临界剪切应力 τc）的影响) 在不同的干燥时间。此外，该研究旨在建立 τc 和 kd 与某些土壤特征之间的关系。取自伊拉克底格里斯河岸边的 18 个未受干扰的两种生物结皮类型蓝藻和叶绿体土壤样品以及裸露土壤，并在实验室中使用微型 JET 在 5、8 和 12 天的干燥时间进行测试, 以模拟田间条件。据观察，在整个观察期间，死藻仍然附着在土壤颗粒上并将其结合在一起，这有助于土壤稳定性，并增加分解前的水分和养分保留。随着两种生物结皮干燥时间的增加，统计结果显示 kd 减少，而 τc 值增加。kd 随盐浓度、有机质和碳酸钙的增加而降低，而 τc 增加。由于藻壳和土壤颗粒之间的生物结壳发生反应，增加了有机质和碳酸钙，因此没有观察到土壤的 pH 值发生变化。本研究讨论了使用 JET 仪器的好处；包括减少测试时间、节约能源、