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Although the total annual precipitation in most parts of Ontario is sufficient to satisfy gross evaporative demands of vegetation the time distribution with respect to these demands is unsatisfactory. For perennial vegetation the April to October period is that in which practically all the evapotranspiration takes place. Potential evapotranspiration during this period is in the order of 20-22 inches in Southern Ontario, while rainfall averages about 18 inches. Furthermore rainfall in June and July frequently falls two to three inches below evaporative demands for each of these months. Irrigation can be used to supplement rainfall and ensure that moisture deficiencies resulting in de creased crop production do not occur. The number of irrigations will depend upon the moisture storage characteristics of the soil, and the magnitude and time distribution of seasonal rain fall. A method will be presented for computing the magnitude of moisture deficiency and number of seasonal irrigations. This method will be applied to four levels of soil moisture storage at eleven locations in Southern Ontario for ten years of perennial crop.
water deficit and irrigation needs in ontario
Ayers, H.D. 1965. WATER DEFICIT AND IRRIGATION NEEDS IN Ontario. Canadian Agricultural Engineering 7(1):37-39.