WEATHER AND WHEAT YIELD IN WESTERN CANADA: I. INFLUENCE OF RAINFALL AND TEMPERATURE DURING THE GROWING SEASON ON PLOT YIELDS

Abstract

A statistical study of plot yields recorded at a number of agricultural experiment stations in central and southern Saskatchewan and Alberta has demonstrated a significant correlation between yield and the amount and distribution of seasonal rainfall. On the whole, above-average rainfall is associated with higher yield, but the result of a given increment of rain at different times is partly dependent on soil conditions. On fertile soil, rainfall prior to harvesting results in a reduction of yield, probably owing to lodging. The maximum influence of precipitation upon yield appears to be exerted during the month of June. The average summer rainfall sequence is very similar in each of the above four districts. There is a moderate degree of correlation between the amounts of rain recorded in different districts during the same season, but the simultaneous occurrence of extremely wet or dry seasons over the whole area seems infrequent.Temperature conditions during the growing season seem to be secondary to rainfall in influencing yield. Above-average temperatures are beneficial at the time of sowing, detrimental during mid-summer and again beneficial prior to ripening, but as in the case of rainfall, the effect produced is influenced by soil conditions. No consistent relation is evident between either rainfall or temperature and the relative yield of early and late maturing varieties.It is apparent that the yields secured are influenced by factors other than those considered, and the precipitation during the autumn, winter and spring months prior to sowing is being studied in this connection.