Long-term changes in heat and moisture related to corn production on the Canadian Prairies

Long-term (approximately 80?years) daily climate records at 12 weather stations across the agricultural production region of the Canadian Prairies were assessed to evaluate trends in seasonal heat units and moisture characteristics for corn (Zea mays). Crop water demand (CWD) and crop water deficit were modelled at each station. Growing season accumulation of these as well as corn heat units (CHU) and rainfall were tested for long-term trends using linear regression. Significant positive trends in CHU were present in the southernmost stations while the northern stations displayed no trend or significant negative trends. Growing season precipitation showed a significant increase on average and most stations showed a positive trend but only one station showed a significant positive trend. CWD declined at most stations with significant negative trends at seven stations. Crop water deficient also declined with significant negative trends at six stations. The spatial variation in these results and those reported in other studies in the region underscores the difficulty involved in forecasting future trends in agroclimatic conditions.