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Many research workers have studied the effects of decreasing moisture content in the soil on plant performance. Mini mum suitable moisture contents have been found to depend on various factors such as the available water capacity of the soil to effective root depth, type of crop, stage of growth and weather conditions. There seems to be general agreement that a suitable minimum for most temperate zone perennial crops is about 50% of the available water capacity (AWC) of the soil (Pairetal. 1969). Field tests of irrigation at Summerland have indicated that irrigating a single plot of alfalfa at 50% AWC maintained the moisture content of the soil within the optimum range (Wilcox, unpublished). When irrigation was started at 50% AWC in orchards the results were quite satisfactory for the first few settings of the sprinkler line (Wilcox and Korven 1964). Lysimeter tests with brome grass gave similar results (Wilcox and Sly 1974).
determining the probable starting dates for irrigating perennial crops
Sly, W.K. and J.C. Wilcox 1976. DETERMINING THE PROBABLE STARTING DATES FOR IRRIGATING PERENNIAL CROPS. Canadian Agricultural Engineering 18(2):6-9.
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