Water use efficiency of dryland maize in the Loess Plateau of China in response to crop management

• Published data on WUE of dryland maize in the Loess Plateau were analyzed.
• The highest yield and WUE were under plastic mulching and the lowest in conventional practice.
• The attainable WUE was 40 kg ha−1 mm−1 in the region.
• The yield-ET relationship indicated that yield was limited by weather and management factors.
• Mulching, cultivar selection, and canopy management need to be integrated for increasing WUE.

Owing to the critical situation of water resources and demographic pressure, improvement of crop water use efficiency (WUE = grain yield per unit seasonal evapotranspiration) in the dryland area of Loess Plateau of China is crucial. The aims of this study were (i) quantifying WUE of dryland maize (Zea mays L.) in the Loess Plateau, and (ii) identifying management practices that improve both WUE and yield. We compiled a data base of 36 sets of experiments spanning more than 20 years, where conventional practice (CT) was compared with alternatives including RT/NT, reduced or no tillage without straw mulching; SM, straw mulching; PM, plastic film mulching 100%; RM, plastic film mulching 50% or more; RMS, ridge mulched with plastic film + furrow mulched with crop straw.Yield ranged from 1.12 to 14.6 Mg ha−1 and WUE from 2.8 to 39.0 kg ha−1 mm−1; the maximum yield and WUE were achieved under RM, PM and RMS and the minimum under CT. Practices had small and inconsistent effect on seasonal evapotranspiration, hence variation in yield and WUE were attributable to changes in both the contribution of soil evaporation to total evapotranspiration and the partitioning of seasonal water use before and after silking. The yield-evapotranspiration relationship indicated that attainable WUE was 40 kg ha−1 mm−1. Few crops, however, reached this efficiency emphasizing the opportunities for improvement. Implications for crop management and further improvement in yield and WUE are discussed.