An Improved Method for Quantifying Soil Aggregate Stability

Soil aggregate stability influences many biophysical and agronomic processes while acting as a key soil health indicator, yet current quantification methods suffer shortcomings including lack of repeatability, inadequate control over input energy, and inaccuracies in coarse-textured soils or those with multi-modal size distributions. In response, we propose a new method deemed integrated aggregate stability (IAS) to interpret aggregate stability using a laser diffraction (LD) machine. This method corrects for underlying particle-size distributions and provides a comprehensive metric of aggregate stability. As verification, we presented repeatability tests that demonstrate the precision of the IAS method, and then compared IAS measurements to wet sieving results for three different soils. Overall, IAS showed higher correlation with the wet sieving method (R² = 0.49 to 0.59) than the median aggregate size (d50), which represents the most common current method for quantifying aggregate stability (R² = 0.09 to 0.27). Further, IAS can estimate the proportions of macro (>0.25 mm) and micro (