A simplified and rapid technique to determine an aggregate stability coefficient in coarse grained soils

Abstract

Soil aggregation determines soil structure and hence influences soil physical, chemical and biological processes. To express soil aggregate stability a variety of indices are discussed in literature. However, the available measures are more suitable to soils with low stone contents while there is currently no established method for stone-rich soils.On an Alpine slope where soil texture is dominated by particles >2mm in diameter, 108 soil samples were collected from the 0–20cm layer and split into 0–10cm (n=108) and 10–20cm (n=59) layers, resulting in 167 analyzed subsamples. Two methods were used to determine soil aggregate stability: (i) A ‘classical’ wet sieving approach as basis for calculating the mean weight diameter (MWD), and (ii) a new technique (aggregate stability coefficient—ASC), adapted to soils with high stone contents and reducing work effort to a minimum.The newly introduced ASC correlated closely with the MWD at all considered soil depths (0–20cm layer: r=0.84, R2=0.85, p<0.01, n=108) showing a comparable precision.The ASC is a useful aggregate stability indicator for stone-rich soils which can be used to evaluate near-surface soil stability, particularly in mountainous environments prone to erosion processes.