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Deep Subsurface Micro-irrigation to Increase Water Use Efficiency in Washington Vineyards

Funding Agency: WSDA Specialty Crop Block Grant Program
WSU Investigators: Pete W. Jacoby, S. Hossein Sadeghi, Sindhuja Sankaran, and Lav R. Khot


During three growing seasons from 2015 through 2017, vines receiving direct root-zone (DRZ) irrigation at rates reduced to 60, 30, and 15% of commercial drip irrigation (DI) exhibited greater crop water use efficiency than did vines under surface drip irrigation.  Each growing season presented climatic differences that resulted in varying levels of water stress on grape development and quality, as well as vine vigor. Overall, DRZ drip irrigation demonstrated the ability to maintain a level of grape production equivalent to no less than 70% of commercial production, but with considerable savings in water resources. No differences were found among depths of DRZ delivery of water from 1-,2-, or 3-foot below soil surface. This project produced one peer reviewed publication during 2017 and several more are anticipated to be published during 2018. Funding for this project will terminate in April 2018 but the final report for the project has been extended for 6 months to allow incorporation of data from the 2018 growing season.