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

Summary

This observational study of 54 Swiss monitoring sites demonstrates that incorporating temporary grasslands into crop rotations significantly enhances soil organic carbon storage both in topsoil and subsoil to 50 cm depth, with a linear dose–response relationship. The authors developed a novel bulk density correction method and found that a 10% increase in temporary grassland proportion yields a SOC gain of 0.40 ± 0.13 kg C m⁻². The findings underscore the importance of accounting for subsoil responses in carbon sequestration assessments, as neglecting them would substantially underestimate the effect of grassland inclusion on agricultural soil carbon storage.

UK applicability

The findings are potentially applicable to UK temperate agriculture, as climatic and soil conditions in parts of the UK are similar to Switzerland. However, site-specific validation would be needed to account for differences in UK soil types, management practices, and crop varieties, and to assess transferability of the bulk density correction model across different pedological contexts.

Key measures

SOC stock (kg C m⁻²) at 0–20 cm and 20–50 cm depths; bulk density of fine soil (<2 mm); proportion of temporary grasslands in crop rotation; topsoil and subsoil response to grassland proportion

Outcomes reported

The study measured soil organic carbon (SOC) stocks in topsoil and subsoil (0–50 cm depth) across cropland and grassland sites, and quantified how the proportion of temporary grasslands in crop rotations affects SOC accumulation. It also developed a methodological correction for bulk density bias in SOC assessments.

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