Carbon storage in agricultural topsoils and subsoils is promoted by including temporary grasslands into the crop rotation

Summary

This study assessed soil organic carbon sequestration potential in Swiss croplands by examining 54 sites with varying proportions of temporary grasslands in crop rotations. Using a novel bulk density correction model, the authors demonstrated that SOC storage potential is substantially greater when accounting for subsoil responses, and that SOC gains are linearly dependent on temporary grassland proportion regardless of soil texture or pH. The findings suggest that managing crop rotations to include grassland phases offers modest but meaningful carbon storage benefits down to deep soil layers, though the climate mitigation potential remains relatively constrained compared to earlier expectations.

UK applicability

The methodological approach (bulk density correction, subsoil assessment) is directly applicable to UK soil monitoring and carbon accounting. However, findings from Swiss agroecosystems may differ in UK conditions due to variations in climate, soil types, and farming practices; local field trials would strengthen confidence in adapting this rotation strategy to UK cropping systems.

Key measures

Soil organic carbon stocks (kg C m⁻²) to 50 cm depth; bulk density corrections; topsoil vs. subsoil responses; temporary grassland proportion in rotation (%)

Outcomes reported

The study quantified how soil organic carbon (SOC) stocks in croplands respond to the inclusion of temporary grasslands in crop rotations, measuring SOC to 50 cm depth across topsoil and subsoil layers. It demonstrated that a 10% increase in temporary grassland proportion increases SOC by 0.40 ± 0.13 kg C m⁻², with equivalent linear responses in both topsoil (0–20 cm) and subsoil (20–50 cm).

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