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Cover Crop Shoot or Root Origin More Important than Legume/Non-Legume Species for Determining the Fate of Residue Input into Distinct Soil Organic Carbon Pools

SSRN, ISSN: 1556-5068
2024
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Metric Options:   Counts1 Year3 Year

Metrics Details

  • Usage
    87

Article Description

The implementation of cover crops has emerged as a promising approach to improve soil organic carbon (SOC) stocks, with particular emphasis on the perceived higher carbon use efficiency displayed by high-quality residues such as from leguminous plants. In this study, we explored how different cover crop residues, specifically from a legume and a grass cover crop, affects soil organic carbon (SOC) formation and its distribution across various soil carbon pools. Over a 7-month period, we incubated 14C-labeled winter rye and hairy vetch residues in microcosms containing soils of varying soil fertility levels from a long-term field trial. We tracked the fate of carbon into free and occluded particulate organic matter (fPOM, oPOM), mineral-associated organic matter (MAOM), and carbon deposited outside the detritusphere.Despite notable differences in residue characteristics such as C:N ratio, chemical composition, and turnover rate, we observed similar SOC formation efficiency between vetch and rye within each plant organ (shoots and roots). Interestingly, the type of plant organ, linked to the lignin content, appeared to exert a greater influence on the fate of cover crop carbon than whether the crop was leguminous or non-leguminous. At medium soil fertility, we found that the largest proportion of cover crop residue C remained as MAOM (15-20%), followed by fPOM (5-12%) and smaller amounts as oPOM (1.5-3.0%). Notably, fPOM and oPOM exhibited opposite responses to residue quality, indicating functional distinctions between these often-pooled POM pools.Soil fertility exerted minimal influence on overall respiration rate patterns or SOC formation, although it did affect oPOM formation efficiency, likely due to differences in soil aggregation. In conclusion, our findings challenge the prevailing assumption regarding the superiority of leguminous cover crops for enhancing long-term SOC accrual. Instead, they underscore the complexity of interactions among residue quality, soil fertility, and SOC formation dynamics.

Bibliographic Details

Tine Engedal; Veronika Hansen; Jim Rasmussen; Jakob Magid; Carsten W. Mueller; Sune Tjalfe Thomsen; Helle Sørensen; Lars Stoumann Stoumann Jensen

Elsevier BV

Multidisciplinary; SOC fractions; residue quality; cover crop; lignin; Root; shoot

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