Abstract During laboratory assessment of the soil water characteristic curve (SWCC), determining equilibrium at various pressures is challenging. This study establishes a methodological framework to identify appropriate experimental duration at each pressure step for the construction of SWCCs via centrifugation. Three common temporal approaches to equilibrium – 24-, 48- and 72-h – are examined, for a grassland and arable soil. The framework highlights the differences in equilibrium duration between the two soils. For both soils, the 24-h treatment significantly overestimated saturation. For the arable site, no significant difference was observed between the 48- and 72-h treatments. Hence, a 48-h treatment was sufficient to determine ‘effective equilibrium’. For the grassland site, the 48- and 72-h treatments differed significantly. This highlights that a more prolonged duration is necessary for some soils to conclusively determine that effective equilibrium has been reached. This framework can be applied to other soils to determine the optimum centrifuge durations for SWCC construction.

中文翻译：

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确定使用离心法构建土壤水分特征曲线的最佳持续时间的方法框架

摘要 在土壤水分特征曲线 (SWCC) 的实验室评估中，确定各种压力下的平衡具有挑战性。本研究建立了一个方法框架，以确定在每个压力步骤中通过离心构建 SWCC 的适当实验持续时间。三种常见的时间平衡方法——24 小时、48 小时和 72 小时——被检查，用于草地和耕地。该框架突出了两种土壤之间平衡持续时间的差异。对于这两种土壤，24 小时处理显着高估了饱和度。对于可耕地，48 小时和 72 小时处理之间没有观察到显着差异。因此，48 小时的处理足以确定“有效平衡”​​。对于草地场地，48 小时和 72 小时的处理有显着差异。这突出表明，某些土壤需要更长的持续时间才能最终确定已达到有效平衡。该框架可应用于其他土壤，以确定 SWCC 施工的最佳离心时间。