ESTIMATES OF PRAIRIE PROVINCIAL WHEAT YIELDS BASED ON PRECIPITATION AND POTENTIAL EVAPOTRANSPIRATION

Abstract

Weather-based estimates of Alberta, Saskatchewan, and Manitoba wheat yields were made for the years 1952–67 by weighting estimates for 42 prairie crop districts according to the number of hectares of wheat per district. The crop-district estimates had been computed from May to July monthly precipitation and estimated potential evapotranspiration (PE) data, and preseason conserved precipitation, using regression equations that had been derived separately for different parts of the prairies. In Saskatchewan, where semiarid climates predominate, variability of wheat yields is high and much of it can be attributed to weather variability. In the most humid province, Manitoba, the yield variation is smallest, and less of this variation can be explained using the weather data. Lack of uniformity in climate, soils, and the sizes of crop districts contributed to several analysis problems, one of which was a bias in the results, particularly in Alberta. Equations based on precipitation and PE were superior to those based on precipitation alone. The estimation procedures can be useful in connection with the transporting and marketing of grain, and in planning future land use.