Optimal irrigation scheduling for wheat production in the Canadian prairies: A modelling study

Food security and reducing malnutrition of the growing world population is a permanent issue in agricultural research. Wheat (Triticum aestivum L.) is an important part of the world food market. The Canadian Prairies comprise the provinces of Alberta, Saskatchewan, and Manitoba which produce very large quantities of wheat, mostly for export. While in many other countries, and in particular in the Middle East and North Africa (MENA) region, wheat is grown with supplemental irrigation, the common practice in Canadian Prairies is to grow wheat as a rain-fed crop. Taking into account the growing pressure on fresh water resources demand and factors of the profitability the possibly optimal use of the irrigation water should be determined according to the its deficit in the region. Thus the set of the optimization problems must be solved: find maximal wheat yield with respect to the limited irrigation water quota and given weather and hydrological data. Systematically solving this problem for different values of the water quota (W) allows to create an irrigation water use efficiency function IWUE = Y (W) which presents the yield as a function of the total irrigation water applied optimally during the season. We demonstrate this approach using the FAO model AquaCrop in conjunction with the TOMLAB optimization library. The results of the model-based optimization show that for this specific case study (Carman,Manitoba 2006) wheat yield could be roughly doubled with limited amount of irrigation water. The average increase of the yield in the range of 0 − 100 mm of irrigation water was more than 20 kg/ha per mm of water.