Final Report – Funding cycles 2021-2023 (two-year project)

Principal Investigator: Pete Jacoby, Washington State University, Pullman

Telephone: 509-475-7630

Cooperators: Scott Williams, Kiona Vineyard and Winery, Benton City, and Todd Tucker, Tuctronics Partnership, Walla Walla

Summary: Data from soil water sensors at Kiona Vineyards during the 2021 and 2022 growing seasons have determined that the best placement of sensors is beneath the emitter or very near the point of water delivery into the soil. Water movement within the soil via capillary action was shown to be in all direction from the point of water release into the soil. In the case of subsurface drip, water movement from the point of release from a delivery tube at 24 inches below the soil surface was observed to enhance soil water content deeper into the soil profile as well as upwards to within 6-7 inches from the surface. Data from these continuously recording sensors also allow a visual assessment of water use by depths of sensor placement throughout the soil profile that occur between irrigation events. By correlation of soil water content and leaf water potential and other measurements of vine activity, irrigation scheduling can become more precise for maintaining vine water stress within desired levels needed for meeting fruit quality goals.

In the use of subsurface drip irrigation, the DRZ (direct root-zone) delivery system has been modified continuously to be more efficiently employed and resistant to root and soil clogging, as well as compatible to mechanical methods used for vineyard surface maintenance and weed control. Single tube placement in close proximity to the vine base is now being employed and evaluated for watering efficiency. Our research has confirmed the ability to save up to 35 percent of water needed to maintain yields when using DRZ versus surface drip. We have also confirmed that DRZ contributes to deeper root development which could create more vine resilience to drought impacts by providing vine the means to access water from the full soil profile.

Irrigation // Viticulture //