Mitigating global warming potential while coordinating economic benefits by optimizing irrigation managements in maize production.

ABSTRACT

China is the second largest irrigated country in the world. Increasing irrigation intensity costs more water and energy, and produces more greenhouse gas (GHG). In the present study, the responses of maize economic and environmental benefits to different irrigation managements were analyzed in a 2-year field study. A purposely designed tube-study was conducted to explore mechanism underlying effects of irrigation managements in detail. Three treatments, rainfed (RF), flood irrigation (FI), and drip irrigation (DI) were included in the field. Five treatments, no irrigation, flood irrigation, irrigation in 0-30, 30-60, and 0-90 cm depth were conducted in the tube study. Compared to RF, grain yields of FI and DI significantly increased by 22.1 % and 35.7 %, respectively, the net ecosystem economic budget significantly increased by 34.2 % and 35.6 %, and carbon footprint decreased by 7.0 % and 12.7 % in the field study. The irrigation treatments in the tube study increased the global warming potential by 12.0-32.8 % and grain yield by 44.5-203.9 %, and reduced GHG intensity by 24.3-57.4 %, compared with no irrigation treatment. Water content at the top soil layer had the greatest impact on GHG emissions. In conclusion, the differences in grain yield and GHG emissions among irrigation managements are mainly due to the soil water content in space and time. Drip irrigation decreases GHG intensity by producing more grain yield due to the optimized soil water distribution in the root zone. Irrigation management with appropriate amount and frequency can increase economic benefit and reduce environmental cost in maize production.