In its 2020-21 fiscal year, the Oregon Wine Board of Directors granted $350,000 to researchers for eight projects with the potential to advance quality grape growing and winemaking in Oregon. The update below is part of a series to let industry members know about the status of these projects.
Dr. Patty Skinkis is a professor and viticulture extension specialist in the Department of Horticulture at Oregon State University and member of the Oregon Wine Research Institute. She has prepared the update for the project below.
This work is being conducted with collaboration from Dr. Paul Schreiner, research plant physiologist, USDA-ARS and Andy Gallagher, Red Hills Soils.
In addition to the OWB grant, support was provided by Erath Family Foundation for soil moisture sensors and equipment. Fruit Growers Lab, Inc. donated tissue nutrient analysis services.
Characterizing Willamette Valley Soil Moisture and Grapevine Response under Drying Seasonal Conditions
- Characterize soil moisture conditions throughout the season among different soil types common to Willamette Valley wine grape production.
- Determine vine water status, growth, and berry development response to weather and soil moisture conditions throughout the season among different soil types.
Importance to the Oregon wine community:
Most Oregon vineyard businesses do not have budgets to support soil moisture and plant water stress monitoring and often are making best-guess estimates on when to initiate irrigation or vineyard floor management practices that influence soil moisture. This project will generate regionally-specific information about soil water content, climatic conditions, and the impacts of these factors on vine growth that will aid others (e.g., growers, management companies, consultants) to determine best management practices.
Progress so far:
Soil moisture, weather data, and vine growth responses were measured in 2020 in a Pinot noir vineyard that had vines of the same age, clone, and rootstock growing on three soil types, including Saum (volcanic), Dupee (sedimentary), and Willamette-Woodburn (marine sediments). Sensors measured soil moisture, soil temperature, and electrical conductivity at two monitoring locations per soil type to a depth of 18 and 36 inches under-vine and in the middle of the alley between rows.
Soil moisture remained relatively consistent through spring, with soil moisture decline starting mid-June, shortly after bloom, and continuing through summer. Soil moisture decline was greatest at the 18” depth. Willamette-Woodburn soil had the greatest decline in soil moisture yet the largest vine size (based on dormant pruning weight), suggesting that the higher vigor vines in that soil type required more water from the soil profile than vines in the other two soils.
There were no clear differences in vine water stress of the three soil types. Berry weight lagged slightly for vines in Willamette-Woodburn, but there were no differences in the berry development curve. By harvest, yields were similar from each soil type. However, the Willamette-Woodburn had lower Brix and sugar per berry compared to the other two soils. Willamette-Woodburn vines also had greater tissue N at véraison and berry YAN at harvest compared to vines in the other two soils. Since the site was not irrigated and no fertilizers added, the differences in growth and berry composition reflect differences in soil fertility and moisture.
We will continue to this project through the 2021 and 2022 growing seasons. Results of the study will be summarized and compared with other soil moisture monitoring efforts in other Willamette Valley research blocks and with the local technical group to determine how the research compares with other vineyards in the region. We will develop future research projects that will build upon foundational knowledge gained from this study (e.g., timing and type of vineyard floor practices).
michael etzel says
What is the floor management of the soil types in the report. Clean cultivated or native cover.? Every other row? or Every row? I believe there has been study done on the benefit of clean cultivation vs. no cultivation in regard to soil moisture at 18 and 36 inches of soil depth. Can you refresh my memory on the study results? Thank you.
Jess Willey says
HI Michael, please see the response from Dr. Skinkis below.
Patty Skinkis says
This project has no tillage of the alleyways, meaning it is resident vegetation of grasses (previously planted) and growth of other vegetation (volunteer, weeds). This was in part becuause we did not want to disrupt the sensor wires that are installed in the soil, and there is great interest in no till systems. The grass is mowed as needed during the season.
I conducted a separate 9-year study comparing no till (grass), alternate till, and tillage of every alley in Jory soils in a commercial vineyard in the Dundee Hills AVA. That trial also monitored soil moisture at depth but it was not continuous monitoring, and it was only one soil type. The results were that N competition of the grass cover, not water stress or soil moisture differences between vineyard floor management, led to changes in vine size over time. We saw smaller pruning weights, lower N status, and lower fruit YAN over time with the no till treatment (grass used in the alleys). That project also had three different stages and different foci of the different stages of the work, all looking at vine and fruit performance over time. Some of the work is published in HortScience (stage II of the studies). In that soil and that specific vineyard, there were no water stress differences between the vineyard floor practices. However, we could not clearly state that the root zone didn’t change over the period of the study to access nutrition and/or water resources. We could clearly see vine canopy changes as a result of the root access to either water and/or N availability in the soil.
The project outlined in the OWB report above is looking at similar measures as the vineyard floor trial, but we are addressing vine growth and performance under different soil types and more soil parameters. We are also monitoring more impacts on fruit development and plant water stress, to observe any seasonal patterns of water stress. This is of particular importance given that vines on different soils may respond differently to seasons as we are experiencing now–warm, dry.
Marcus Goodfellow says
Did you view the changes in canopy of the no till practices as a positive or a negative?
We’ve seen all of the things you cited with no till, lower YANs, pruning weights, etc.
But we also see better balance in acidity(higher percentages of tartaric acid vs. malic), better evolution of skin tannins and pigments(higher levels of sun exposure as green growth is reduced from nitrogen competition), and lower sugar accumulations at physiological ripeness(which given global warming seems desirable to me). It’s also far more cost effective; no tilling, less hedging, less leaf pulling, less management of laterals, etc.(more mowing to be fair). And yields seem to be more consistent from year to year.
Patty Skinkis says
Based on the research results of the vineyard floor trial in my comment above (not the research report above), we found the no till reduced the canopy size to a more manageable level. The vines fell into what was considered moderate vigor based on pruning weights, rather than high vigor. As you noted, these were desirable from a fruit quality perspective and a management/economics perspective with reduced canopy management costs.