Managing the trade-offs among yield increase, water resources inputs and greenhouse gas emissions in irrigated wheat production systems

Irrigation is a crucial measure for ensuring food security; however, the complex linkages among yield increases, water productivity, and greenhouse gas (GHG) emissions are unclear for irrigated wheat production in China. Here a meta-analysis was conducted to determine the trade-offs among yield increase, water productivity, and GHG emissions in irrigated Chinese wheat production systems. Grain yield in wheat irrigation systems with 172 mm of supplemental irrigation water increased by 23% owing to the increase in aboveground biomass, spike number, and grain number, whereas water productivity in irrigated wheat decreased by 6% compared to non-irrigated systems. Water productivity increased from 5.7 to 16.5 kg ha(-1) mm(-1) with conventional irrigation systems to 17.5 kg ha(-1) mm(-1) with optimized irrigation systems, similar to increases found in non-irrigated systems (17.8-18.0 kg ha(-1) mm(-1)). Compared with non-irrigated systems, yield-scaled GHG emissions in irrigated systems decreased by 2 -8% using surface water, and increased by 15-68% using groundwater. Yield-scaled GHG emissions in optimized irrigation systems decreased by 3-19% compared to conventional irrigation systems. In conclusion, irrigation was a crucial practice for ensuring food security, but water productivity and yield scaled GHG emissions should be carefully considered when making design decisions. In the future, adoption of integrated irrigation management systems was crucial to achieve collective improvements in yield, water productivity, and environmental benefits. (C) 2017 Published by Elsevier Ltd.