Straw mulch and nitrogen fertilizer: A viable green solution for enhanced maize benefits and reduced emissions in China

Abstract

Against the backdrop of global warming, the agricultural sector grapples with the dual challenge of safeguarding food security while fulfilling carbon neutrality. Currently, although nitrogen fertilizer and mulch use to enhance maize yields is well-documented, systematic evaluations are lacking in the carbon neutrality potential and holistic benefits, including greenhouse gas (GHG) implications, associated with these strategies. Here, using the calibrated DeNitrification-DeComposition (DNDC) model, we conducted a long-term simulation (1980−2019) incorporating various scenarios of nitrogen fertilizer (N₁: conventional nitrogen fertilizer; N_0.7: 70% conventional nitrogen fertilizer) and mulch (CK: no-mulch; PM: plastic film mulch; SM: straw mulch), resulting in a baseline scenario (CKN₁) and five mitigation scenarios (CKN_0.7, PMN₁, PMN_0.7, SMN₁, SMN_0.7). We revealed an average net global warming potential during the maize growing season of 5293 kg CO₂ eq ha⁻¹, with the most GHG derived from N₂O (53%). Considering GHG costs, the net environmental and economic benefits in maize amounted to 5089 CNY ha⁻¹. Presently, Hainan, Henan, Liaoning, and Jilin provinces exhibit a state of low net global warming potential and high net environmental and economic benefits in maize cultivation. Of the mitigation scenarios, only SMN₁ concurrently reduced GHG emissions (− 59%) and amplified net environmental and economic benefits (+ 21%) in China. Our results, which provide the first calculation of the combined benefits of mulch and nitrogen fertilizer including GHG costs, not only underscore the immense potential of mulch for enabling carbon neutrality, but also offer valuable insights for policymakers and industry in selecting suitable mulch techniques for agricultural production.