Cover crops support the climate change mitigation potential of agroecosystems

as the following crop in spring. Individual impact factors are described in the following sections. 3.1. Carbon land benefit based on yield gain The literature review on the impact of winter cover crop on maize yields revealed that yield effects are highly dependent on the cover crop species or the composition of the cover crop mixture. The yield effect of cover crops on the following crop is also highly dependent on the type of land management. The lower the tillage intensity, the higher the yield increase [18]. The yield increase effect is also much higher in organic farming than in conventional systems. Marcillo and Miguez [24] find a yield increase of 8.0% for a conventional intensive tillage sys- tem, while for an organic reduced tillage system, yields increased by 61.0% when cover crop- ping was implemented. In summary, the considered studies showed a weighted mean maize yield gain due to cover cropping of 8.8% (95% CI, 2.9, 14.8). Fig 1 shows the included yield effect results, confidence intervals and the pooled effect. If more than one result is shown from one study in Fig 1 this literature showed results from mul- tiple experiments. Multiplying the weighted mean yield gain with the average EU-27 maize yield and the car- bon opportunity cost factor for maize (2.10 kg CO2e kg-1 maize [11]) results in a mean carbon land benefit increase of 1.46 Mg CO2e ha-1. 3.2. Carbon sequestration Cover crops have a positive impact on soil organic carbon sequestration in arable soils. The lit-

erature research revealed two meta-analyses with 139 and 1195 studies included. In addition, 26 studies that were not included in the above-mentioned meta-analyses were also included in our calculations. Up to 12.0% of carbon from cover crop biomass can be sequestered as soil organic carbon [13]. Similar to the crop yield effects shown above, the potential of soil organic Fig 1. Forest plot of included literature on yield effects. https://doi.org/10.1371/journal.pone.0302139.g001 PLOS ONE Cover crops support the climate change mitigation potential of agroecosystems PLOS ONE | https://doi.org/10.1371/journal.pone.0302139 May 8, 2024 8 / 20