Traditional aggregate stability methodologies, such as wet sieving, rainfall simulation, and chemical dispersion, measure aggregate size, rather than stability. Sonication methods allow for energy-based measurements of aggregate stability, but most methods involve sieving to obtain gravimetric measurements of particle size fractions, which increases labor and variability compared to volumetric measurements by laser diffraction analyses. One criticism of energy-based methods is that ultrasonic devices are calibrated in a closed vessel containing water whereas the application of energy in routine analyses is commonly done in an open system containing soil and water, without considering the effects of soil mass and specific heat on sonication power or the energy lost from the system by conduction and/or other forces in an open system. Using texturally diverse subsoil samples with low carbon and similar clay mineralogy, we quantified 1) the effects of system type (thermodynamically closed versus open systems) and 2) the effect of assuming energy from calibrations in water versus measuring thermal energy in a soil–water system on soil dispersion curves. We found that these factors do not significantly affect soil dispersion curves of coarse- and medium-textured soils; however, fine samples are affected by system type and the method used to quantify energy. Overall, indices produced from soil dispersion curves are highly reproducible in both open and closed systems and correlate with soil physical properties that impact aggregate stability. These indices may streamline future measurements of aggregate stability and facilitate the inclusion of this important soil property in soil assessments.

中文翻译：

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使用基于能量的激光衍射法测定高岭石底土中的骨料稳定性


传统的骨料稳定性方法，如湿筛分、降雨模拟和化学分散，衡量的是骨料大小，而不是稳定性。超声处理方法允许对聚集体稳定性进行基于能量的测量，但大多数方法涉及筛分以获得粒度分数的重量测量，与激光衍射分析的体积测量相比，这增加了劳动力和可变性。对基于能量的方法的一个批评是，超声波设备是在装有水的封闭容器中校准的，而常规分析中的能量应用通常是在包含土壤和水的开放系统中进行的，而不考虑土壤质量和比热对超声处理功率的影响，或者通过开放系统中的传导和/或其他力从系统中损失的能量。使用具有低碳和类似粘土矿物学的质地多样的底土样品，我们量化了 1） 系统类型（热力学封闭系统与开放系统）的影响，以及 2） 从水中校准中假设能量与测量土壤-水系统中热能对土壤分散曲线的影响。我们发现这些因素对粗质地和中等质地土壤的土壤分散曲线没有显著影响;但是，精细样品会受到系统类型和用于量化能量的方法的影响。总体而言，土壤分散曲线生成的指数在开放和封闭系统中都具有高度可重复性，并且与影响团聚体稳定性的土壤物理特性相关。这些指数可以简化未来对骨料稳定性的测量，并有助于将这一重要的土壤特性纳入土壤评估。