Progress report for FW16-034
Water management in vineyards continues to be major issue in California.
Limited water availability is predicted to be a serious problem if the current climate warming trends and drought continue.
The use of a vineyard specific crop model has the potential to reduce water use and become an effective irrigation management tool. Crop models incorporate climate, soil, vineyard, and irrigation data to accurately estimate vine water status and recommend irrigation to meet production objectives.
This project will compare the existing grower practice of ET based irrigation scheduling with the use of a vineyard specific irrigation model known as VINTEL, demonstrate the benefits of using a crop specific model in vineyard management and develop a blueprint for the implementation of such models.
During year one of this project (2016 growing season) we showed that the VINTEL model provided an acceptable estimation of water status under our growing conditions and that irrigating based on the model’s recommendation has the potential to save 10-30% compared to the grower’s current practice of ET based deficit irrigation.
During year two (2017 growing season) we irrigated using the model recommendations and monitored plant health and fruit quality. We observed a water savings of 50-60% compared to the grower standard of ET based deficit irrigation. However, this was determined to be too aggressive of a deficit as a late season heat spike resulted in severe water stress and crop loss in some areas.
During year three (2018 growing season) we will modify the Vintel custom green zone, irrigate using the model recommendations, monitor plant health and fruit quality, incorporate model refinements to improve overall accuracy.
Year 2 objectives included:
- Irrigation scheduling based model recommendations.
- Continuing site assessment throughout growing season to confirm correctness of annual variables and adjust model parameters as required.
- Comparing model to grower standard (ET model)
- Comparing harvest data from blocks irrigated using the model to blocks irrigated using the grower standard
- In partnership with The Vineyard Team host a field day focusing on technology and irrigation.
During Year 2 of this project we accomplished the following:
- Installed soil moisture probes. Due to soil conditions on this particular property manual soil moisture assessment very arduous. Plant available water measurements are required for model confirmation.
- Compared model to grower standard (ET model) WSARE_2018-Annual-Report_Figure1_Grower-Standard-vs.-Vintel.
- Collected and analyzed juice samples to monitor maturity development WSARE_2018-Annual-Report_Table1_2017-Harvest-Data.
- Visually assessed each site throughout growing season to confirm correctness of annual variables and adjusted model parameters as required. Annual variables include canopy width, canopy height, cover crop width, and canopy porosity.
Impacts and Contributions/Outcomes
Year 2 of this project resulted in the following outcomes:
- Irrigating based on the Vintel vineyard specific crop model resulted in a water savings of 50-60% when compared to the grower’s ET based irrigation management. WSARE_2018-Annual-Report_Figure1_Grower-Standard-vs.-Vintel compares grower applied water with VINTEL recommendations in Chardonnay. Block C96A was irrigated using ET based calculations. Total water use was 254 gal per vine. Blocks C96B, C and E were irrigated using the Vintel recommendations. Total water use ranged from 99-126 gallons per vine. We observed similar savings in Sauvignon Blanc and Pinot Noir. During the Labor Day period of 2017 we experienced a severe heat spell with temperatures reaching 108 degrees Fahrenheit on the property. The Pinot Noir experienced severe water stress and some crop loss. The model did not accurately anticipate the need for additional irrigation. We will irrigate using the model recommendations during the 2018 season, however, we will modify the parameters so that the plants can better endure periods of high heat or make additional irrigations and revert to model after the heat subsides.
- Despite the drastic reduction in water we did not observe any difference in yield or juice chemistry at time of harvest for Chardonnay. WSARE_2018-Annual-Report_Table1_2017-Harvest-Data shows the Brix, pH and TA (g/l) of Chardonnay at time of harvest. These parameters are used by winemakers to determine ripeness and harvest dates. Actual harvest dates varied based on client winery stylistic goals. This table also shows the final yield in tons per acre. C96A is the grower standard and irrigated using ET calculations. C96B, C and E were irrigated using the model. C96B has historically higher yields so we do not consider number a results of irrigation. We will compare this harvest data again in 2018.
- As stated in the previous report real time irrigation data is needed to provide more accurate and timely irrigation information. Flow meters were installed in 2017 but found to be incompatible with our irrigation system. Flow meters will be redesigned and installed in 2018. Data from these meters will feed directly to the crop model.
Educational & Outreach Activities
- On August 3, 2017 we hosted a tailgate session in conjunction with The Vineyard Team (project outreach partner) focusing on technology and irrigation. Approximately 30 growers/interested parties in attendance. WSARE_2018-Annual-Report_Vineyard-Team-Tailgate-08032017
- On November 14, 2017 sat on a panel at the Sustainable Ag Expo in San Luis Obispo, CA discussing Grower-Driven Research funded by the SARE program (http://sustainableagexpo.org). Approximately 60 people attended the session.