Impacts of Recent Climate Trends on Agriculture in Southwestern Ontario

Abstract

In this paper, precipitation, temperature and crop water deficit during the past 80 years in southwestern Ontario are reviewed in terms of their impacts on the region’s present and future field-crop production. Although the generally drier (average annual precipitation ≈ 750 mm) and warmer (average annual air temperature ≈ 9.5 °C) weather in the region during the last decade produced greater average annual crop water deficits (≈ 150 mm yr−1) than during the previous 30 to 40 years, the situation is not as severe as during the 1930s. It is likely, however, that the negative impacts of climate on the region’s field-crop production (yields often ≤ 50% of potential) are greater now than ever before because of more intensive agriculture, fewer pastures/wetlands/woodlots, and greater water demands by increasing population and industry. To mitigate the current negative weather effects, the region’s field-crop sector is adopting drip irrigation technologies (more efficient than the traditional overhead gun systems) which have been shown in recent trials to increase tomato yields by 50–80% over those not irrigated. In addition, combined drainage-surface runoff-irrigation technologies (’closed loop’ water management systems) are being developed which can increase corn and soybean yields by up to 90% and 50%, respectively, while simultaneously decreasing agrochemical and sediment degradation of the off-field environment. If the current climate trend persists, it may be necessary to develop new drought- and heat-resistant field crops as well as updated guidelines for nutrient and pest management.