Pulse Brain · Growing Health Evidence Index
Tier 3 — Observational / field trialPeer-reviewed

Quantifying cover crop-derived above- and belowground carbon inputs including rhizodeposition

Veronika Hansen, Tine Engedal, Jakob Rasmusen, Maria Skovgaard Andersen, Jakob Magid, Lars Stoumann Jensen

Agriculture Ecosystems & Environment · 2025

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Summary

This field study employed multiple-pulse ¹⁴CO₂ isotopic labelling to quantify above- and belowground carbon inputs from three cover crop species grown on contrasting soils. Total net carbon input ranged from 1100–3200 kg C ha⁻¹, with belowground inputs contributing 32–64 % of total inputs and rhizodeposition accounting for 27–42 % of topsoil carbon. The research reveals that cover crops allocate substantial carbon to both topsoil and subsoil via roots and rhizodeposition, with up to 39 % of belowground carbon reaching subsoil depths.

UK applicability

The findings are relevant to UK arable systems considering cover crops for soil carbon sequestration and climate change mitigation. However, the study was conducted in Denmark on sandy and loamy soils; UK farms encompass diverse soil types and climatic zones, so site-specific quantification of carbon inputs would strengthen applicability for UK practice and policy.

Key measures

Total net carbon input (kg C ha⁻¹) to 110 cm depth; aboveground and belowground carbon allocation; rhizodeposition carbon flux; carbon distribution in topsoil (0–20 cm) and subsoil (20–110 cm); ¹⁴C tracing of assimilated carbon over 3-month growth period

Outcomes reported

The study quantified total above- and belowground net carbon inputs from three cover crop species (oilseed radish, winter rye, hairy vetch) across two contrasting soil types, using isotopic labelling to trace carbon distribution to 110 cm depth. Results demonstrated substantial carbon transfer to soil via rhizodeposition and subsoil allocation, with species and site differences in total carbon accumulation.

Theme
Climate & resilience
Subject
Soil carbon & organic matter
Study type
Research
Study design
Field trial
Source type
Peer-reviewed study
Status
Published
Geography
Denmark
System type
Arable cereals
DOI
10.1016/j.agee.2025.109668
Catalogue ID
SNmoqqscsj-0slgjp

Topic tags

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