WaSHI Annual Report FY25

Eastern WA Wine Grape Systems LTARE

Prosser, WA

A four-panel timeline image showing the progression of a vineyard from 2022 to 2025. 2022: Bare soil with protective grow tubes and trellis posts, no visible vegetation. 2023: Small grapevines emerging between rows of grow tubes, soil still mostly exposed. 2024: Vines are noticeably larger with green foliage, rows filled with grass or cover crops between them. 2025: Mature grapevines with dense green leaves, well-established rows, and visible irrigation lines. The background in all panels shows rolling hills under a clear sky, illustrating vineyard development over time.
This experiment includes 2 wine grape varieties grown with 5 combinations of vineyard management activities.

The Washington Soil Health Initiative (WaSHI) Vineyard LTARE at Prosser continues to advance its mission of improving soil health and sustainability in irrigated wine grape systems. This site was established to answer critical questions about how soil health-building practices influence vineyard resilience, grape quality, and long-term sustainability under the unique conditions of the Columbia Basin.

In fall 2024, the team conducted deep soil sampling across all treatment replicates to establish post-treatment baselines. Samples were collected from both under-vine and alleyway positions in Cabernet Sauvignon and Chardonnay blocks at five depth intervals (0–15 cm to 60–90 cm).

Analyses included:

• Carbon fractions (total, organic, and inorganic carbon).

• Biological indicators such as phospholipid fatty acids (PLFA) for microbial biomass.

• Chemical properties including pH, electrical conductivity (EC), cation exchange capacity (CEC), and available phosphorus.

• Functional indicators like permanganate-oxidizable carbon (POXC), ACE protein, and mineralizable carbon.

Vineyard Management

The 2024–2025 growing season marked the second year of vine establishment under five contrasting management systems. Key management activities included:

• Pruning and training vines to four buds in spring 2025

• Cover crop reseeding in under-vine and alley zones

• Targeted irrigation and fertilization, with synthetic fertilizer applied through drip irrigation in May and June 2025.

Side-by-side images showing cover crops in a vineyard setting. Left image: Close-up of green cover crop plants growing between rows of soil, with a black drip irrigation line running horizontally across the top portion. The plants appear dense and healthy. Right image: A wider view of a vineyard row with young grapevines protected by light-colored grow tubes. The ground between rows is covered with green cover crop vegetation, creating a grassy strip. Both images highlight soil coverage and vegetation management in vineyard systems.
Cover crops have been established undervine (left) and in tractor rows (right).

Outreach and Engagement

The Prosser LTARE team actively shared findings through several outlets. These efforts have strengthened industry awareness of soil health practices and fostered dialogue on sustainable viticulture.

  • Presentations at the Washington State Grape Society Annual Meeting, WAVEx webinars, and national conferences.
  • Field tours for growers, researchers, and policymakers, including visits from U.S. Congressional representatives and international scientists.
  • Popular press coverage, including features in Good Fruit Grower, Washington Grown Magazine, and the Sustainable Winegrowing Podcast.

Challenges and Adaptations

The team faced several barriers, including labor shortages for critical vineyard tasks, rodent damage to young vines and moisture sensors, and equipment limitations, requiring upgrades to irrigation filtration systems and under-vine mowing strategies.

Solutions included partnerships with industry for donated vines, enhanced rodent control, and contracting skilled vineyard crews. These adaptations have improved vineyard uniformity and management efficiency.

A close-up view of a white tree guard or grow tube in a vineyard or orchard setting, surrounded by green vegetation and weeds. A tall mustard plant with broad leaves and a thick root is growing at the base of the tube, with smaller weeds scattered around on dry, brown soil. In the background, rows of similar tubes and trellis wires are visible under a bright blue sky with scattered clouds. Provide your feedback on BizChat
LTARE treatments are helping wine grape producers optimize their vineyard for both soil health and weed management.
A person wearing a light gray long-sleeve shirt is seated in front of complex laboratory equipment. The setup includes metallic components, wires, and tubing in red, green, and black colors, suggesting a scientific or technical environment such as an analytical instrument or experimental apparatus. The background shows multiple connected devices and machinery with a mix of shiny metal surfaces and control panels.

Devin Rippner

USDA Agriculture Research Service

A person is standing in a young orchard with rows of evenly spaced trees protected by white grow tubes. Drip irrigation lines run along the rows, and the soil between rows is mostly bare with patches of grass. The individual is wearing a blue plaid shirt, a dark graphic T-shirt, and a navy cap with sunglasses resting on top. In the background, there are rolling hills under a cloudy sky, and the orchard extends into the distance.

Liz Gillispie

Washington State University