Integrated spatial–temporal analysis of crop water productivity of winter wheat in Hai Basin

• Average CWP of Hai Basin winter wheat is relatively low and could be increased.
• Field data show linear relation ET-yield; CWP increase linked to yield increase.
• Efforts to increase CWP should focus on yield increase, not only water savings.

Achieving higher yield per unit of water is one of the most important challenges in water-limited agriculture. In this paper, crop water productivity (CWP) of winter wheat was calculated and analyzed in the plain of Hai Basin in northeastern China. The average CWP of winter wheat (Triticumaestivum L.) in the basin for 2003–2009 was 1.049 kg m−3, with CWP values across the basin ranging between 0.7 and 1.4 kg m−3. The spatial analysis of the relationships among CWP, yield, and evapotranspiration (ET) across the basin showed a strongly linear relationship between ET and yield (R2 = 0.86). The temporal analysis showed increases in yield of between 100.4–211.4 kg ha−1 year−1 between 1984 and 2002 at eight agro-meteorological research stations across the basin without a corresponding increase in ET, corresponding to an increase in CWP of 0.02–0.1 kg m−3 per year. It was concluded that the improvements in CWP have resulted from improvements in crop varieties and crop husbandry rather than reductions in water consumption.