Spatiotemporal Variation in Crop Demand for Irrigation Water and Its Determinants: Take Northwest Shandong Province as an Example.

Objective Agricultural production in most regions in northern China relies on irrigation. Understanding spatiotemporal variation of the demand of different crops for water is critical to improving agricultural management. Taking the northwest Shandong province as an example, this paper studies the change in its demand for irrigation. Method We took winter wheat as the model plant, and calculated its water demand based on the Penman-Monteith formula. Spatiotemporal variation in the water demand was analyzed using the Mann-Kendall mutation test, the inverse distance weighting and the interpolation method. The factors that affect the water demand was calculated using the Pearson correlation analysis method. Result Annual average irrigation water demand of the winter wheat is 339 mm, but has been increasing. Spatially, distribution of irrigation water demand is ring-shaped across the studied region, with the shape of the rings varying with growth season. The relative humidity and sunshine duration are the factors that affect the irrigation water most, with the former negatively correlated while the latter positively correlated with the irrigation water demand, both at significant level. Conclusion The irrigation water demand of winter wheat in northwest Shandong province has been increasing. Spatially, it increases from the northeast to the southwest. Precipitation cannot meet the demand of the wheat during its seeding, returning green and elongation stages. Topping up the soil water by irrigation is hence required. [ABSTRACT FROM AUTHOR]