Sustainable soil carbon sequestration practices need to be rapidly scaled up and implemented to contribute to climate change mitigation. We highlight that the major potential for carbon sequestration is in cropland soils, especially those with large yield gaps and/or large historic soil organic carbon losses. The implementation of soil carbon sequestration measures requires a diverse set of options, each adapted to local soil conditions and management opportunities, and accounting for site-specific trade-offs. We propose the establishment of a soil information system containing localised information on soil group, degradation status, crop yield gap, and the associated carbon-sequestration potentials, as well as the provision of incentives and policies to translate management options into region- and soil-specific practices.

The assumption that crop-land natural climate solutions (NCS) have benefits for both climate change mitigation and crop production remains largely untested. Here we model GHG emissions and crop yields from crop-land NCS through the end of the century. We find that favourable (win–win) outcomes were the exception not the norm; grass cover crops with no tillage lead to cumulative global GHG mitigation of 32.6 Pg CO₂ equivalent, 95% confidence interval (29.5, 35.7), by 2050 but reduce cumulative crop yields by 4.8 Pg, 95% confidence interval (4.0, 5.7). Legume cover crops with no tillage result in favourable outcomes through 2050 but increase GHG emissions for some regions by 2100. Crop-lands with low soil nitrogen and high clay are more likely to have favourable outcomes. Avoiding crop losses, we find modest GHG mitigation benefits from crop-land NCS, 4.4 Pg CO₂ equivalent, 95% confidence interval (4.2, 4.6) by 2050, indicating crop-land soil will constitute a fraction of food system decarbonization.