Relay strip intercropping of soybeans and maize achieves high net ecosystem economic benefits by boosting land output and alleviating greenhouse gas emissions.

Abstract

Background: Cereal-legume intercropping provides a solution for achieving global food security, but the mechanism of greenhouse gas emissions and net ecosystem economic benefits of maize-soybean relay intercropping are poorly understood. Hence, we conducted a two-factor experiment to investigate the effects of cropping systems, containing maize-soybean relay intercropping (IMS), monoculture maize (M) and monoculture soybean (S), as well as three nitrogen levels at 0 (N0), 180 (N1), 240 (N2) kg N ha^-1 on crop grain yield, greenhouse gas emissions, soil carbon stock and net ecosystem economic benefit (NEEB).

Results: The average grain yield of IMS (7.7 t ha^-1) increased by 28.5% and 242.4% compared with M (6.0 t ha^-1) and S (2.2 t ha^-1). The land equivalent ratio (LER) of IMS was 2.0, which was mainly contributed by maize (partial LER: 1.2) rather than soybean (partial LER: 0.8). Although the total grain yield of IMS remarkably enhanced by 43.6% and 45.5% in N1 and N2 contrast in N0, the LER was 37.5% and 38.6% lower in N1 and N2 than in N0. The net global warming potential (GWP) of maize and soybean was 11.6% and 1.8% lower in IMS than in the corresponding monoculture, which resulted from a decline in GWP and enhanced soil organic carbon stock rate. Moreover, NEEB was 133.5% higher in IMS (14 032.0 Chinese yuan per year) than in M, mainly resulting from an increase in total economic gains and a decline in GWP cost. A more robust response in yield gain rather than total costs to N inputs of IMS led to 46.8% and 48.3% higher NEEB in N1 and N2 than in N0.

Conclusion: Maize-soybean relay intercropping with 180 kg N ha^-1 application can obtain yield advantages without raising environmental costs, which provides an approach to achieving sustainable agricultural production. © 2024 Society of Chemical Industry.