Evaluating a line source irrigation system for determining water requirements of herbaceous perennials

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Journal of Environmental Horticulture




Horticultural Research Institute

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We investigated wind effects on the water distribution pattern of a line source irrigation system experimental design that creates a decreasing linear moisture gradient and the growth of twelve perennial wildflower species. Species were randomly assigned to rows perpendicular to a main line of spray irrigation heads, parallel to the decreasing irrigation rates, and irrigated at 110% of evapotranspirationat the heads. At low wind speed (0.44 m/s, 1.4 ft/s), application rates decreased linearly from 50 mm/hr (2 in/hr) for positions closest to the irrigation line to zero at 4 m (12 ft) from the irrigation line. Application rates at positions farthest from the irrigation line were affected by wind speeds as low as 1 m/s (3.3 ft/s). At high wind speeds (3.8 m/s, 12.5 ft/s), application rates at all positions averaged the same across all positions but with extremely high variability. We detected a water stress response in several species known to be drought sensitive. A line source irrigation design offers a potential way to efficiently assess the response of a large number of perennial species to varying irrigation rates by creating a linear moisture gradient, but only when applied under low wind speeds.