Location: Soil, Water & Air Resources Research2010 Annual Report
1a. Objectives (from AD-416)
1) Develop a measurement/modeling technique to identify components of evapotranspiration in temperate and semi-arid vineyard systems. 2) Define strategies for excess water removal and/or water conservation in vineyards for moist temperate regions of the Southeastern U.S. (North Carolina). 3) Define strategies for water conservation in vineyards for semi-arid regions of Israel (Arad valley).
1b. Approach (from AD-416)
Water management could be significantly improved if the components of evapotranspiration in the vineyard systems (i.e. vines, and grassed and/or bare interrows) could be quantified and appropriately manipulated. The components of the vineyard system (vines, grass, and soil) have seasonally variable water loss from transpiration and/or evaporation, and the natural water supply from rainfall does not necessarily coincide with periods of maximum water usage by any of these system components. The measurement technique that we have envisioned is based on a combination of Bowen ratio techniques for total evapotranspiration and a soil heat balance technique for evaporation. The regular Bowen ratio technique would allow determination of all components of evapotranspiration in the vineyard in a single lumped term. The micro Bowen ratio technique (~ 6 cm tall), installed below the grape canopy, would allow determination of evapotranspiration corresponding to the interrow treatment (e.g., grass or bare). Finally, the soil heat balance technique would allow determination of the soil component of evapotranspiration (i.e. evaporation). By difference between these three estimates, we could determine grape transpiration, interrow transpiration, and evaporation. Utilizing this combination technique, we can characterize the daily, seasonal, and total water use from each vineyard system component.
3. Progress Report
The focus of this research is improving water-use efficiency in vineyards under humid subtropical (North Carolina) and semi-arid Mediterranean (Israel) climate conditions. As such, the project relates to the Agricultural Ecosystem Impacts and Changes in Weather and the Water Cycle at Farm, Ranch, and Regional Scales components of NP 204. The growing of grapes for table consumption or the making of wine is a large and expanding industry in the southeastern U.S. A significant cost of vineyard development and operation is water management, primarily relating to the use of drainage and irrigation systems. Water management in vineyards could be significantly improved if the individual components of water use (transpiration by grape vines and grass between the vines and water evaporation from bare soil) could be quantified and efficiently managed. Water use in vineyards is seasonally variable depending on plant growth and weather patterns. The natural water supply from rainfall does not necessarily coincide with periods of maximum water use. Therefore, managing soil water storage is important because if there is too much or too little water available to the vines at critical times there is a large impact on the quantity and quality of grapes produced with significant economic consequences. This project has three objectives: 1) develop a measurement/modeling technique to identify components of evapotranspiration in temperate and semi-arid vineyard systems, 2) define strategies for excess water removal and/or water conservation in vineyards for moist temperate regions of the Southeastern U.S. (North Carolina), and 3) define strategies for water conservation in vineyards for semi-arid regions of Israel (Arad valley). Progress on this new project was limited to Objective 1 this year. Some new measurements systems were developed specifically for the conditions in the vineyards of this study. A meeting of the investigators in North Carolina was held in January to finalize the design of the measurement systems and discuss details concerning the deployment of these systems. The systems were delivered to the field sites in April. Continuous measurements of evaporation and associated weather parameters are now being made above the vines, below the vines, and in the soil at both study sites. All data is recorded on-site and wireless communication allows transmission of the data back to the laboratory. Data from these measurements will enable testing of a mathematical model to predict how much evaporation occurs from the vines and how much from the grass and soil. These predictions and data from the next two growing seasons will be used to address Objectives 2 and 3, the development of strategies to improve water management in vineyards. Project cooperators have met twice, once at an annual scientific conference and once in North Carolina, communicate frequently via email, and occasionally via telephone.