The ability of soils to aggregate, more than the state of aggregation, promotes protected soil organic matter formation

Summary

This laboratory study demonstrates that soil aggregation capacity—rather than current aggregation state alone—is a key determinant of organic carbon stabilisation in mineral soils. Using isotopically labelled plant inputs, the authors traced how soluble inputs preferentially stabilise as mineral-associated organic carbon whilst structural inputs stabilise via aggregate protection, with highly aggregated soils showing greater resilience to disturbance and faster aggregate regeneration around structural inputs.

UK applicability

The findings are relevant to UK arable and pastoral soils, particularly fine-textured soils common in lowland Britain. Soil management practices aimed at SOC accrual should account for inherent aggregation potential and recovery capacity, informing tillage decisions and input type selection for different soil types.

Key measures

13C-enriched structural and soluble plant inputs; MAOC and POC formation and persistence; soil aggregation levels before and after disturbance; aggregate regeneration capacity

Outcomes reported

The study traced the formation and stabilisation of mineral-associated organic carbon (MAOC) and particulate organic carbon (POC) in soils with differing aggregation levels using 13C-enriched plant inputs. It measured how soil disturbance and input type affected carbon persistence across soil types with inherently different aggregation capacities.

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