Land-Use Intensity Effects on Soil Organic Carbon Accumulation Rates and Mechanisms

Summary

This study examined soil carbon sequestration potential across a gradient of land-use intensities (conventional to native forest) on a single soil series, using complementary fractionation methods to identify mechanisms of carbon storage. Carbon accumulated predominantly within soil aggregates, particularly in macro-aggregate heavy-fraction pools, with rates inversely related to management intensity. The work demonstrates that tillage disruption of aggregates rapidly mobilises stored carbon from slow to active pools, undermining long-term sequestration.

Regional applicability

The study was conducted in the United States on a single soil series, so direct transferability to United Kingdom conditions is limited by soil type and climate differences. However, the mechanistic insights on aggregate-protected carbon storage and the carbon cost of tillage are broadly applicable to UK temperate arable and mixed farming systems, and the methodology provides a framework for similar assessments on UK soils.

Key measures

Soil organic matter fractions (density- and incubation-based); carbon accumulation rates (g C m⁻² y⁻¹); aggregate size classes (>250 μm macroaggregates, 53–250 μm microaggregates, <53 μm); carbon pool residence times (weeks to decades)

Outcomes reported

The study quantified soil organic matter accumulation rates across ten managed and successional ecosystems on the same soil type, identifying the soil fractions and mechanisms responsible for carbon sequestration. Carbon storage rates ranged from 8.9 to 31.6 g C m⁻² y⁻¹ depending on land-use intensity and ecosystem type.

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