Within-field variation in root-to-shoot ratios and root traits in spring barley: Implications for estimating carbon inputs

Summary

This field study demonstrates substantial within-field and between-year variability in root-to-shoot ratios and root morphological traits in spring barley grown on contrasting soil types in southwestern Sweden. Root and shoot biomass were uncorrelated, undermining the assumption of fixed root-to-shoot ratios commonly used in soil carbon models. The findings highlight the plastic nature of root systems and suggest that improved mechanistic understanding of drivers for root allocation and trait responses is necessary to refine field-scale estimates of root-derived carbon inputs and soil organic carbon model accuracy.

UK applicability

The study was conducted in Sweden on Cambisols and related soil types; applicability to UK cereal production depends on soil type alignment (some UK soils are taxonomically similar, others are not). The methodological approach and findings regarding root trait plasticity and spatial heterogeneity are likely relevant to UK barley and wheat cultivation, though site-specific validation would be needed to inform national soil carbon accounting and model parameterisation.

Key measures

Root-to-shoot ratios; root diameter; root length density; root tissue density; shoot and root biomass; depth-stratified sampling (0–40 cm); spatial variation at 50 × 50 cm grid resolution; between-year variation

Outcomes reported

The study quantified within-field spatial and temporal variation in root-to-shoot ratios and root traits (diameter, length density, tissue density) in spring barley across three soil types. Shoot and root biomass were not correlated, resulting in variable root-to-shoot ratios with coefficients of variation of 7–18% and no consistent spatial pattern between years.

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