Water Requirement of Irrigated Garlic

Abstract: A replicated field trial was conducted on the West side of the San Joaquin Valley to determine the crop coefficient and water requirement of irrigated garlic. Irrigation systems used included flood irrigation, subsurface drip irrigation, and surface drip irrigation. Irrigation levels were set at 50, 75, 100, 125% of crop evapotranspiration measured using a weighing lysimeter. Field plots consisted of four beds 80 m long and a meter wide with the two inside beds used for experimental purposes and the outside beds as buffers. Irrigation scheduling was controlled by the crop lysimeter using ETc threshold values; 1 mm for the subsurface drip irrigation, 2 mm for the surface drip irrigation, and a weekly irrigation equal to the accumulated ET for the flood. The crop water use for the interval March 1 to May 21, 2006 was 425 mm with 108 mm of rainfall during this period. The irrigation schedule was modified to reflect the rainfall contribution. The total yield was related to the total applied water with a maximum occurring at one hundred percent ETc. Statistically there is very little difference in the yield parameters and quality parameters when compared across irrigation system types with statistical differences occurring between the irrigation levels. Peak crop coefficient values were estimated in the range of 1.3 to 1.4. There appears to be a good correlation between percent crop cover and crop coefficient that needs to be further explored with garlic and other crops.