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GRAPEGROWING two vineyard blocks were planted on different rootstocks, 420A and 110R. The actual vineyard evapotranspiration differed between the two blocks according to the influence of the rootstocks. A commercial 15-acre vineyard of Chardonnay near Esparto, Calif., had three sub-blocks of 5 acres each where surface renewal was validated against eddy covariance in 2013. Different irrigation treatments were applied to each block. Surface renewal ET measurements matched eddy covariance ET measurements in each block and irrigation treatment. A surface-renewal station was installed in a commercial 35-acre table grape vineyard site in Delano, Calif., in 2013. A station was installed in a 35-acre Cabernet Sauvignon vineyard in Paso Robles, Calif., in 2013. I), 7 acres of Cabernet Sauvignon and a 10-acre Merlot block. How surface renewal works Solar energy absorbed by a vineyard vaporizes water, is conducted into the ground or warms the air. This is called an energy balance and is considered on the scale of a field, not an individual vine. The amount of energy that vaporizes water (latent heat of evaporation) is obtained algebraically by first measuring the light energy (net radiation), then subtracting from it the ground conduction energy (soil heat flux) and the air-warming energy (sensible heat flux). The energy that vaporizes water can be converted to the mass of water evaporated from the vineyard (actual evapotranspiration) using a basic units conversion because the amount of energy Case study required to vaporize a given volume of Wente Vineyards has led adoption of the water is very close to constant. new technology. Throughout the 2013 The size of the area, or footprint, over season, the vineyard and winemaking which surface renewal measures evapoteam used four surface-renewal stations transpiration depends on the height of in four separate vineyards to monitor the instruments above the vine canopy actual vineyard evapotranspiration and and local environmental conditions. The vine water status. Two of the vineyards footprint increases as the height of the are hillside sites. The total 52 acres temperature sensor increases. Mori_Nov05.qxt includes 10 acres of9/19/05 3:29 PM Page 1 For practical application, the maxiCabernet Sauvignon, 25 acres of Cabernet Sauvignon (Figure mum sensor height is limited by the clearance of a sprayer. For most vineyard and sprayer configurations, the maximum temperature sensor height (10 feet) allows surface renewal to measure approximately 5 acres. Conversely, for small vineyard blocks, the temperature sensor can be closer (7 feet) to the vine canopy so that surface renewal effectively measures a 2- to 3-acre area. PWV Bibliography 1. Paw U, K.T., J. Qiu, H.B. Su, T. Watanabe, Y. Brunet. 1995 "Surface renewal analysis: a new method to obtain scalar fluxes without velocity data." Agricultural & Forest Meteorology. 74: 119–137. 2. Shapland, T.M., R.L. Snyder, K.T. Paw U, A.J. McElrone. 2014 "Thermocouple frequency response compensation leads to convergence of the surface renewal alpha calibration." Agricultural & Forest Meteorology. In Press. 3. Williams, L.E., J.E. Ayars. 2005 "Grapevine water use and the crop coefficient are linear functions of the shaded area measured beneath the canopy." Agricultural & Forest Meteorology. 132: 201–211. 4. Williams, L.E., 2001 "Irrigation of winegrapes in California." Practical Winery & Vineyard. practicalwinery.com/ novdec01p42.htm. Outstanding Tanks for Outstanding Wines SUPPLIERS OF QUALITY VIRUS CERTIFIED GRAFTED GRAPEVINES Deadline for Custom Grafted Order For Spring Planting is January of Previous Year For Further Information & Pricing Please Call or Write 1912 Concession 4 R.R. #2 Niagara-on-the-Lake Ontario, Canada LOS 1J0 Phone: 905-468-0822 Fax: 905-468-0344 Affordable Custom Tanks and Fermentors Semi-automatic Fillers Membrane Presses Rocket M-7 Semi-automatic Series Filters Corkers and Cappers "Excellent quality at reasonable prices with exceptional customer service built around an understanding of vintners' needs." ~ Jim Schultz, Windy Oaks Winery Mio Vigneto Products, Inc. Wine Tanks, Fermentors, and Winery Equipment Visit us at www.miovigneto.com Email dwightb@miovigneto.com Call Dwight Busalacchi at (415) 531-6450 pr actica l win ery & vin eya r d F EB RUARY 20 14 63