Agricultural land management practices that restore soil organic carbon (SOC) are increasingly presented as climate solutions that also increase yields. But how often these benefits coincide at the farm level—the extent of farmer decision-making—remains uncertain. We investigated the concurrent responses of SOC and yield to cover crops, including their direct association, with a global meta-analysis. Cover crops simultaneously increased yields and SOC in 59.7% of 434 paired observations. Increasing SOC directly increased crop yields in soils with initial SOC concentrations below 11.6 g kg ^-1 ; for example, a change from 5 g kg ^-1 to 6 g kg ^-1increased revenues by +2.4 %. These yield benefits of SOC did not decrease when N inputs were increased or when legume cover crops were used, indicating that fertility inputs cannot substitute for SOC effects. Regardless of the direct effects of increasing SOC on yield, the largest yield increases (up to +24.3 %) resulted from the inclusion of legume cover crops in systems with ^simplified  by rotation or with nitrogen inputs < 157 kg ha −1 season ^-1 N. increasing SOC more than non-legumes (up to +1.5 g kg ^-1 ). By simultaneously increasing yields and SOC, the cover crop provides an opportunity to benefit both food security and climate, including through direct returns from increased SOC on low-carbon soils.

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