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An improved method for measurement of soil aggregate stability using laser granulometry applied at regional scale
Author(s) -
Rawlins B. G.,
Turner G.,
Wragg J.,
McLachlan P.,
Lark R. M.
Publication year - 2015
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12250
Subject(s) - granulometry , soil water , aggregate (composite) , soil science , soil test , soil carbon , environmental science , wetting , mineralogy , moisture , chemistry , geology , materials science , composite material , sediment , geomorphology
Summary Laboratory‐based aggregate stability ( AS ) tests should be applied to material wetted to a moisture content comparable with that of a field soil. We have improved our original laser granulometer ( LG )‐based AS test published in this journal by including a pre‐wetting stage. Our method estimates disaggregation reduction ( DR ; µm) for a soil sample (1–2‐mm diameter aggregates). Soils with more stable aggregates have larger DR values. We apply the new technique to soils from 60 cultivated sites across eastern E ngland, with ten samples from each of six different parent material ( PM ) types encompassing a wide range of soil organic carbon ( SOC ) concentrations (1.2–7.0%). There are large differences between the median DR values (rescaled to < 500 µm) for soils over the PM types, which when used as a predictor (in combination with SOC concentration) accounted for 53% of the variation in DR . There was no evidence for including an interaction term between PM class and SOC concentration for the prediction of DR . After applying the aggregate stability tests with the 60 regional soil samples, they were stored for 9 months and the tests were repeated, resulting in a small but statistically significant increase in DR for samples from some, but not all, PM types. We show how a palaeosol excavated from a site in southern E ngland can be used as an aggregate reference material ( RM ) to monitor the reproducibility of our technique. It has been suggested that soil quality, measured by critical soil physical properties, may decline if the organic carbon concentration is less than a critical threshold. Our results show that, for aggregate stability, any such thresholds are specific to the PM .