Water Use Efficiency and Eco-Niche-Yield Prediction of Rainfed Wheat in China’s Loess Plateau

A twenty-three year study of water use efficiency and related parameters on a 0.44 ha. rainfed wheat field resulted in the following new data- Yield averaged 2135.13±sigma841.08 (minimum 810~maximum 3923 kgha-1); Water Use Efficiency(Y/ET) = 6.23±2.06 (2.84~10.21 kgha-1mm-1); Precipitation during the fallow period = 301.7±107.6 (129.8~498.2 mm); Water storage in 5~210 cm soil layer at about sowing = 328.41±78.72 (177.3~453.8 mm); Soil evaporation during the fallow period = 195±60.14 (72.6~347.1 mm); Precipitation storage = 106.7±66.3 (-22~234.2 mm); Precipitation storage efficiency % = 32.61±16.22 (-16.9~53.3); Precipitation during the growing season = 234.6±57.39 (139.8~400.6 mm); Precipitation in May = 54.91±38.69 (8.8~142.1 mm); Water storage in 5~210 cm soil layer just after harvest averaged 220.35±46.15 (123.3~335.3 mm); EvapoTranspiration during the growing season averaged 342.6±84.29 (220.5~586.6 mm). WUE benchmarks were proposed for the first time to the region as follows- >=5 kgha-1mm-1 for very poor and poor years; >=9 kgha-1mm-1 for medium and good years; and >=12 kgha-1mm-1 for excellent years. A novel model using precipitation and soil parameters before sowing was well correlated with yields. Using the first digital clustered five eco-niche-yield types and based on the model predictions, management recommendations beforehand may help growers to approach the eco-niche-yield potentials with rational input.