Summary
This study validates a simple, practical index for assessing soil organic matter based on the ratio of soil organic carbon to clay content, using data from 3,809 sites across England and Wales sampled in 1978–83. Specific threshold values (SOC/clay ratios of 1/8, 1/10 and 1/13) demarcate boundaries between degraded, moderate, good and very good soil structural condition, with land use identified as the strongest explanatory variable. The authors propose this index as a scalable tool for national and regional soil evaluation and monitoring, potentially applicable to other European soils in similar climatic zones.
UK applicability
The index was directly validated using the National Soil Inventory of England and Wales and should be directly applicable to UK soil assessment and monitoring at national and regional scales. Given the broad range of soils and land uses in the dataset, the methodology should support soil management evaluation across UK agricultural systems.
Key measures
Soil organic carbon (SOC) to clay ratio; SOC/clay thresholds for soil structural quality classification; percentage of sites in each structural condition category by land use; variance in SOC/clay ratio explained by land use, soil type, precipitation and pH
Outcomes reported
The study validated an index based on the soil organic carbon (SOC) to clay ratio as a method for assessing soil structural quality across arable, grassland and woodland sites. It established threshold values (1/8, 1/10, 1/13) that distinguish between 'very good', 'good', 'moderate' and 'degraded' soil structural conditions.
Topic tags
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