Effects of Subsurface Micro-irrigation on Water Use Efficiency and Grapevine Growth

View the project final report

Commodities

• Fruits: grapes

Practices

• Crop Production: drought tolerance, greenhouses, irrigation, water management
• Education and Training: demonstration, display, extension, mentoring, networking, on-farm/ranch research, participatory research, workshop
• Production Systems: agroecosystems

Grape-based agriculture in the western SARE region has been a major industry historically with rapid expansion occurring in recent decades in the Pacific Northwest. However, water for crop irrigation now faces potential limits owing to multiple competing demands from the public as well as from changing climatic patterns. Agriculturalists are currently being forced to make essential decisions ranging from crop selection to management strategies in order to maintain sustainable operations. Owing to moisture losses associated with surface evaporation and weed growth under conventional surface irrigation methods, development of more highly efficient irrigation methods are necessary for producers to meet this resource use challenge. Working in close collaboration with vineyard owners and managers in southcentral Washington, our research group recently introduced a new subsurface micro-irrigation strategy which uses hard tubes placed vertically into soil to deliver water directly into the lower root zone of certain perennial crops such as grapes. During the 2015 growing season, one of the hottest and driest on record, we were able to produce 70 percent of commercial production using direct root-zone irrigation while conserving 85 percent of the water applied by surface drip irrigation to achieve full commercial production. We anticipate that this study will clarify the advantages of our new irrigation method for growers when coping with water scarcity in the western region of the U.S., and also gain a better understanding of growth capacities of grapevines under water stress. These results will be translated to growers through an integrated applied research and educational program with primary objectives focused on:  1) advancing the understanding of the role of water in allocation of carbohydrates within the grape vine; and 2) extension education programming directed by a logic model developed to guide project activities. Our proposed activity plan is based on stakeholder input and involvement, sound experimental design involving statistical principles, and an educational programming model containing proven methods. We will utilize on-farm demonstration, formal educational programs containing learning assessment, and surveys to track rate of adoption by growers and determination of resulting economic impact to the grape-based industry in the western U.S.

Overall goal: Achieve comprehensive understanding of subsurface micro-irrigation impacts on grapevine growth and wine quality by determining minimal amounts of water required to achieve acceptable fruit quality. Growers will be directly engaged with this project through planned program activities to translate research-based findings to provide efficient and sustainable irrigation methods for vineyard managers to utilize during periods of limited water availability.

Objective 1: Evaluate efficiency of our subsurface micro-irrigation strategy on water conservation

• Sub-objective 1: Calculate water saved without diminishing fruit quality [Oct. – Dec. 2017/2018]

• Sub-objective 2: Compare differences in water use efficiency between subsurface micro-irrigation and surface drip irrigation [Oct – Dec. 2017/2018]

• Sub-objective 3: Determine combinations of water delivery amount and irrigation depth yielding highest water use efficiency [Oct – Nov. 2017/2018]

Rationale: Fruit quality includes combinations of relevant nutrients and flavonoids determined through laboratory analyses while water use efficiency will be calculated as a ratio of water required to meet fruit production goals.

Objective 2: Measure the impact of our new subsurface micro-irrigation strategy on grapevine growth and fruit quality

• Sub-objective 1: Assess role of subsurface micro-irrigation strategy in partitioning carbohydrates within the grapevine [Mar.– Nov. 2017/2018]

• Sub-objective 2: Quantify subsurface micro-irrigation effects on root distribution and abscisic acid (ABA) exudation [Apr. – Nov. 2017/2018]

• Sub-objective 3: Analyze vital nutrient content in grapes [Oct. – Mar. 2017/2018]

Rationale: Carbohydrate partitioning, root distribution and ABA content are three key factors related to grapevine growth. Evaluating the grapevine health and fruit quality from these factors will help determine efficiency of subsurface micro-irrigation using our method.

Objective 3: Educate vineyard producers and engage community members on irrigation water conservation and wine grape quality improvement

• Sub-objective 1: Conduct extension workshops to educate producers about improving wine grape quality by using less irrigation water [Feb. & Aug. 2017/2018]

• Sub-objective 2: Develop educational materials for vineyard managers and growers to conserve irrigation water and improve water use efficiency [Jan. 2017 – Apr. 2018]

Rationale: This objective will enable vineyard producers directly participating in our educational extension activities to achieve water resource conservation and adopt sustainable agricultural irrigation methods.

Measurable Milestones:

• Determine water use efficiency under various application strategies of subsurface micro-irrigation
• Analyze fruit quality under different water delivery amounts and irrigation depths
• Contrast grapevine growth under subsurface micro-irrigation versus surface drip irrigation
• Develop and deliver educational materials for vineyard producers
• Attract 100 producers to participate in extension workshops and assess learning outcomes.

Future Orientations: This two-year project could become a longer-term project based on grower demand.  Additionally, educational activities and publications will interest more grape producers in water conservation and sustainable agriculture. Future funding might be achieved through conference fees or commodity funded grants.