Sustainable crop production under future climates: national mapping of cover-crop rotations and soil organic carbon–N2O trade-offs

Abstract Sustainable crop production increasingly depends on rotation designs that raise productivity while lowering reactive nitrogen (N) losses and net greenhouse gases. We conduct a national, spatial analysis for Germany, evaluating diversified 4-year rotations with alternating legume/non-legume cover crops (CCs) under future climates (RCP4.5/8.5, six GCMs). Using the DSSAT crop–soil model coupled to dynamic Tier-2 N₂O accounting (driven by DSSAT-simulated fertilizer, residue, and leached N), we map impacts on yield, N use efficiency (NUE), N leaching, ΔSOC, and net GHG relative to business-as-usual rotations. Across the ensemble, legume-inclusive CC sequences increase cereal yields by ~16–33% (zone-dependent), improve NUE, and reduce N leaching by ~40%. Systems accrue additional SOC but approach plateaus over decades; N₂O responses are climate- and soil-contingent, yet the net GHG footprint falls by ~35–45% on average through 2099 when ΔSOC and direct + indirect N₂O are jointly considered. Accounting for upstream seed and diesel for CCs may slightly attenuates (but does not negate) the net benefit. Spatial “leverage maps” reveal where rotation redesign most robustly delivers the triad of higher production, lower N losses, and lower net GHG, and where trade-offs persist. Results provide policy-ready evidence that targeted, legume-inclusive cover-crop rotations can advance cleaner crop production in temperate regions under changing climate.