Impact of irrigation and fertilization regimes on greenhouse gas emissions from soil of mulching cultivated maize (Zea mays L.) field in the upper reaches of Yellow River, China

Greenhouse gas emissions from agricultural soil are strongly affected by the field practices including fertilization, irrigation and cultivation model. Understanding the mechanism of greenhouse gas emissions from soil and their impact factors is essential for cleaner agricultural production and global greenhouse gas mitigation. This paper investigated greenhouse gas emissions from soil of mulching cultivated maize (Zea mays L.) field under different irrigation and fertilization regimes. Border and drip irrigation with different schedules were implemented in the upper reaches of Yellow River, China. Border irrigation included three different irrigation depths (180, 315 and 450 mm), and drip irrigation was controlled by a tensiometer and triggered by three different matric potentials (−15, −25 and −35 kPa). Three nitrogen fertilizer levels (350, 250 and 150 kg ha⁻¹) were applied for the drip irrigation triggered by the matric potential of −25 kPa. Soil acted as a sink of CH₄ in the semiarid site regardless of irrigation and nitrogen fertilization regimes. Irrigation scheduling had no significant influence on CO₂ emissions, but the irrigation method did have. Cumulative CO₂ emissions increased by 24.7% for drip irrigation compared with border irrigation at the same water and nitrogen fertilizer levels. Cumulative CO₂ emissions for the high nitrogen fertilizer treatment (350 kg ha⁻¹) increased by 19.3% in comparison with the medium and low levels under drip irrigation. N₂O emissions were positively related to the irrigation depth under both drip and border irrigation. Cumulative N₂O emissions reduced by 23.5% for drip irrigation compared with border irrigation at the same water and nitrogen fertilizer levels. N₂O emissions increased with the increase in nitrogen fertilizer application under drip irrigation. Drip irrigation with high frequency (−15 kPa) and medium nitrogen fertilization (250 kg ha⁻¹) obtained the best economic and environmental performance through comprehensive evaluation of the yield, water and fertilizer productivity, global warming potential, greenhouse gas intensity and net ecosystem economic budget. The findings can provide an opportunity for greenhouse gas mitigation without crop yield reduction following the proper irrigation and fertilization regimes in the semiarid region.