Location: Soil, Water & Air Resources Research2011 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
This project is under National Program 212 Climate Change, Soils, and Emissions as it relates to climate impacts on water availability and water use by crops. The focus of this research is improving water-use efficiency in vineyards under humid subtropical (North Carolina) and semi-arid Mediterranean (Israel) conditions. This 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 eating or the making of wine is a rapidly expanding enterprise in the southeastern U.S. Water use in vineyards varies by season and depends on vine growth and weather patterns. The natural water supply from rainfall does not always provide water when it is needed by grapevines. Managing the amount of water stored in the soil 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 and potentially significant economic consequences. Water management in vineyards could be significantly improved if the individual components of water use by grape vines and grass between the vines and evaporation from bare soil could be accurately measured and efficiently managed. This project has three objectives: 1) develop a measurement/modeling technique to identify components of water use 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., and 3) define strategies for water conservation in vineyards for semi-arid regions (Israel). Activities during the second year of this project were primarily with regard to Objective 1. New measurement systems developed specifically for the conditions in the vineyards of this study have been deployed and are operating. 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 are recorded on-site and wireless communication allows transmission of the data back to the laboratory. Preliminary data analysis has begun and the initial assessment is that the data collected appear promising although adjustments to measurement techniques continue. 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 and how management practices can optimize water use by the vines. These predictions and data from the next growing season will be used to address Objectives 2 and 3, the development of strategies to improve water management in vineyards. The project principal investigator (PI) from North Carolina State University traveled to Israel in May for discussions with the Israeli partners and to address instrument optimization and data analysis. Project cooperators communicate frequently via email, and occasionally via telephone.