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

Summary

This study assessed how including temporary grasslands in crop rotations affects soil organic carbon (SOC) storage in Swiss agricultural soils, using a novel bulk density correction method. Analysis of 54 permanent grassland and cropland sites revealed that SOC responses to grassland inclusion were linear and equivalent between topsoil and subsoil layers, with each 10% increase in temporary grassland proportion yielding 0.40 ± 0.13 kg C m−2 gain. The findings suggest that whilst agricultural soils offer modest but meaningful carbon sequestration potential, proper accounting of subsoil responses and bulk density artefacts is essential for accurate assessment.

UK applicability

The methodology and findings are relevant to UK arable and mixed farming systems, though results from Swiss conditions (soil types, climate, management practices) may not directly transfer. UK research using similar monitoring networks and correction approaches could help quantify grassland ley rotation benefits for carbon storage in British soils.

Key measures

Soil organic carbon stocks (kg C m−2) at 0–20 cm and 20–50 cm depths; bulk density corrections; temporary grassland proportion in crop rotation; comparison between cropland and permanent grassland sites

Outcomes reported

The study measured soil organic carbon (SOC) stocks in topsoil and subsoil layers across croplands with varying proportions of temporary grasslands, and quantified the relationship between grassland inclusion and carbon sequestration potential. It demonstrated that increasing temporary grassland proportion by 10% would increase SOC by 0.40 ± 0.13 kg C m−2 down to 50 cm depth.

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