Wheat/pea intercropping with reduced nitrogen inputs maintains crop productivity but lowers soil nitrate residues and N2O emissions: Evidence at crop and cropping system levels

Abstract

Cereal-legume intercropping is a promising strategy for enhancing agricultural productivity while reducing nitrogen (N) fertilizer inputs. However, the extent to which intercropping systems combined with optimized N input can simultaneously deliver high agronomic productivity, low environmental impact, and favorable economic performance remains insufficiently resolved. To address this issue, a two-year field experiment involving wheat monoculture, pea monoculture, and wheat/pea strip intercropping was conducted under crop-specific N application rates. Wheat received 0, 180, and 240 kg N ha–1, pea received 0, 90, and 135 kg N ha–1, with the same crop-specific N rates used in both monoculture and intercropping. The results demonstrated that wheat/pea intercropping significantly increased system grain yield (13.03%), N uptake (8.67%), and N use efficiency (8.50%) compared with the monoculture-based predicted values. This intercropping system also reduced overall soil nitrate N residues and nitrous oxide emissions by 8.29% and 6.62%, respectively. In addition, the intercropping system generated the highest net economic benefit at 135 kg N ha–1. These advantages were predominantly driven by the wheat component. A comprehensive evaluation further revealed that wheat/pea strip intercropping combined with 135 kg N ha–1 exhibited the best system performance in terms of agronomic productivity, reduced environmental impacts, and economic performance. Collectively, these findings suggest that this intercropping–N management strategy can simultaneously enhance food security, boost farmers’ economic returns, and mitigate environmental pressures in the Guanzhong Plain, offering a short-term pathway to improve cropping system sustainability.