Intercropping achieves long-term dual goals of yield gains and soil N2O emission mitigation

Mitigating nitrous oxide ($N_2$O) emissions from agricultural soil is imperative for addressing climate change. Although diversified cropping systems have the potential to augment yields, their impact on soil $N_2$O emissions over a long-term scale remains inconclusive. We measured crop yield and soil $N_2$O emissions across eight consecutive years based on a positioned plot field experiment, using a constructed monocropping system as a control. We found that maize–potato intercropping after nitrogen (N) fertilisation elevated crop yields by 0.6 Mg ha⁻¹ to 1.2 Mg ha⁻¹ and decreased area- and yield-scaled $N_2$O emissions by 5.2%–14.5% and 19.0%–20.6%, respectively, compared with the expected monocropping. Furthermore, the intercropping-induced $N_2$O emissions reduction was more pronounced in the initial phase (first 3 years) and stabilised at a lower level in the later phase (last 5 years); it increased with N application rates. The altered nosZ gene abundance and nitrate-N (NO${}_3^{-}$-N) content in soil, alongside N uptake by crops, primarily contributed to the $N_2$O emission reduction after intercropping. The results confirm that long-term intercropping has a positive, but cropping duration-dependent, effect on yield gain and $N_2$O emission mitigation. This offers a valuable reference for employing crop diversification to simultaneously address food security and climate change.