Improved sustainability of grain production by intercropping and partial organic substitution in the North China Plain

Abstract

Context

Introduction of intercropping with legumes and partial organic nitrogen (N) substitution is thought to benefit the sustainability of grain production systems but there is a need for better evidence on the effectiveness and economic outcomes of these measures.

Objective

Here, we assess whether integrating maize/soybean intercropping and partial organic substitution into maize-wheat double cropping can reduce annual N inputs while sustaining high productivity and profitability, and simultaneously lowering N surplus and greenhouse gas emissions.

Methods

Field experiment was conducted for three cropping systems (maize-wheat, soybean-wheat, and maize/soybean intercrop-wheat) and two fertilizer treatments: 100 % synthetic N and 30 % organic N substitution.

Results and conclusions

Over two years, soybean-wheat and intercrop-wheat produced 17.7 % and 14.3 % higher grain protein yields than maize-wheat, but total grain yield was lower by 36.8 % and 9.2 %, respectively. N surpluses were reduced by 40.7 % and 14.9 % in soybean-wheat and intercrop-wheat, respectively. As a result, soil mineral N accumulation was 18.5 % and 12.5 % lower in soybean-wheat and intercrop-wheat, respectively, than in maize-wheat. Correspondingly, greenhouse gas emissions were reduced by 35.1 % and 26.0 %. Net revenue from intercrop-wheat was 16.4 % higher than that of maize-wheat in the first year. Organic N substitution reduced soil N accumulation and N₂O emissions without affecting other performance indicators.

Significance

These results demonstrate that intercropping and partial organic fertilizer substitution can reduce environmental impacts while maintaining economic viability, supporting the adoption of these practices in the North China Plain for more sustainable grain production.