Do cover crops impact labile C more than total C? Data synthesis

Abstract

The potential of cover crops (CC) to increase total soil organic C (SOC) concentration can be inconsistent, but labile SOC is considered to be more sensitive to management than total SOC. This leads to two questions: Do CCs impact labile SOC more than total SOC? Do CCs increase labile SOC more rapidly than total SOC? This review compares CC impacts on labile and total SOC based on CC studies reporting both parameters up to 31 Dec 2022. Labile and total SOC concentrations were measured in 31 CC study locations. Cover crops increased labile SOC concentration in 58% (18 of 31) and had no effect in 42% (13 of 31) of locations, suggesting CCs do not increase labile SOC in all cases. Within the 18 locations, CCs increased labile SOC without increasing total SOC in only 19% (6 of 31 locations), while in the rest (12 of 31) of locations, CCs increased both labile and total SOC. Thus, CCs increased labile SOC more rapidly than total SOC in only one-fifth of cases. Also, the few studies that monitored changes in labile SOC with time found CCs do not always increase labile more rapidly than total SOC. In the 12 locations where CCs increased both labile and total SOC, CCs increased labile SOC by 54 ± 30% and total SOC by 23 ± 10%, indicating CCs can increase labile SOC by about two times compared with total SOC in some locations. Increased CC biomass production and reduced residue decomposition can increase labile SOC.Overall, CCs increase labile SOC in most cases but may not always increase labile SOC more rapidly than total SOC although more CC studies monitoring changes in SOC pools with time are needed to better understand CC impacts on SOC fractions under different CC management scenarios and climatic conditions.

Potential gains in soil carbon and nitrogen as a result of systems perenniality: Insights from on‐farm experiments and soil organic matter fractions

“…net GHC and yield‐scale emissions) of cover crops were comparable to no cover crops in semi‐arid irrigated conditions (Acharya et al., 2022). Similar SOM responses to cover cropping were observed in a 5‐year field experiment (Anuo et al., 2023) and a literature synthesis (Blanco‐Canqui, 2022, 2023), suggesting that the impacts of cover crop practices on potential soil C sequestration and N retention are site and management specific (e.g. cover crop species selection, soil properties and climate).…”

Impacts of the tillage systems on the production of green corn (Zea mays L.) in long‐term plots in Northeastern Brazil

“…The adoption of sustainable farming systems can promote improvements in soil physical quality, ultimately leading to enhanced crop production (Yadav et al., 2021). The results indicate that the use of soil tillage systems, coupled with soil‐protecting previous crops in a long‐term experiment, led to increased productivity, especially in plots cultivated under MT, which exhibited a higher carbon content (Blanco‐Canqui, 2023), thus indicating the sustainability of this production system.…”

“…Furthermore, green corn NBS stresses the importance of preserving soil organic matter, enhancing soil structure, increasing root volume, boosting Soil Organic Carbon (SOC) levels, and reducing soil compaction and Mechanical Resistance to Penetration (MRP) (Blanco‐Canqui, 2023; Cavalieri‐Polizeli et al., 2022; Liu et al., 2022). SOC serves multiple vital functions, including stabilizing soil structure, protecting microaggregates, regulating nutrient release, decreasing soil bulk density, and optimizing water infiltration and retention.…”

“…SOC serves multiple vital functions, including stabilizing soil structure, protecting microaggregates, regulating nutrient release, decreasing soil bulk density, and optimizing water infiltration and retention. These functions are fundamental for sustaining soil health and, consequently, ensuring agricultural productivity (Blanco‐Canqui, 2023; Salassi et al., 2002).…”

Science Mapping of Meta-Analysis in Agricultural Science

“…Agriculture faces an increasing number of challenges, such as ensuring ecosystem services and resolving apparent conflicts between them [17]. Papers published in agricultural journals provide a large amount of experimental data, which can be reviewed, integrated, and analyzed through statistical techniques, providing theoretical guidance for solving these challenges [18]. Meta-analysis can more accurately quantify the interaction between farming system performance and soil and climate conditions in the environmental and socio-economic contexts [17,19,20].…”