Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2008
Publication Date: 10/15/2008
Citation: Ayars, J.E. Water requirement of irrigated garlic. Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)51(5):1683-1688, 2008. Interpretive Summary: Agriculture on the west side of the San Joaquin Valley is undergoing a major shift in cropping from moderately salt tolerant and salt tolerant field crops (tomato, cotton) to more salt sensitive horticultural crop such as pepper, lettuce, and garlic. This transition is a result of reduce water availability due to drought and environmental allocations and a lack of a suitable drainage water disposal system. There is very little information on the water requirements of these new crops and a project was developed to determine the water requirements for horticultural crops grown in a moderately saline environment using furrow irrigation, surface drip, and subsurface drip irrigation. Furrow irrigation is traditionally used in this area but there is increasing use of subsurface drip. This experiment determined the water requirement of garlic. The data showed that 425 mm of water was required to fully meet the crop water requirement. Less than full irrigation resulted in yield loss and irrigation in excess of 100% of crop needs did not provide any yield advantage. There will not be any opportunity to save water by irrigation at less than 100% crop demand and still maintain yields with this crop.
Technical Abstract: A replicated field trial was conducted on the West side of the San Joaquin Valley to determine the crop coefficient and water requirements 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 these values. The total yield was related to the total applied water with a maximum occurring at one hundred percent ET. Statistically there is very little difference in the yield parameters and quality parameters when compared are crossed 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.