Location: Crops Pathology and Genetics ResearchTitle: Comparison of a stand-alone surface renewal method to weighing lysimetry and eddy covariance for determining vineyard evapotranspiration and vine water stress
|SHAPLAND, THOMAS - University Of California|
|WILLIAMS, LARRY - University Of California|
|CALDERON-ORELLANA, ARTURO - University Of California|
|SNYDER, RICHARD - University Of California|
|KYAW, THA PAW U - University Of California, Davis|
Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2019
Publication Date: 10/16/2019
Citation: Parry, C.K., Shapland, T.M., Williams, L.E., Calderon-Orellana, A., Snyder, R.L., Kyaw, T., McElrone, A.J. 2019. Comparison of a stand-alone surface renewal method to weighing lysimetry and eddy covariance for determining vineyard evapotranspiration and vine water stress. Irrigation Science. 37:737-749. https://doi.org/10.1007/s00271-019-00626-6.
Interpretive Summary: Our newly developed surface renewal (SR) technique holds tremendous potential as a technology that can provide growers with inexpensive, real-time, and site-specific crop water loss measurements. Here we validated the effectiveness of our new SR system against expensive research grade methods that are considered gold standards for measuring crop water loss. We found very tight correlation between our new SR measurements crop water loss and a stress index determined with the other methods. These results reinforce the tremendous potential for SR to provide growers with essential information needed to efficiently manage irrigation of their crop, and the method should work effectively across most crops.
Technical Abstract: Surface renewal (SR) is a bio-meteorological technique that uses high frequency air temperature measurements above a plant canopy to estimate sensible heat flux density. The sensible heat flux is then used to estimate latent heat flux as the residual of a surface energy balance equation. SR previously relied on calibration against other methods (e.g. Eddy Covariance) to obtain accurate measurements of sensible heat flux density, and this need for calibration limited the use of SR to research applications. Our group recently showed that compensating the frequency response characteristics of SR thermocouples converges the calibration factor near the theoretically predicted value (Shapland et al. 2014). This led to the development of an inexpensive, stand-alone SR system to measure sensible heat flux without the need for calibration, and we used a mature vineyard containing a weighing lysimeter to validate this new method. Vineyard evapotranspiration (ET) measured with SR was strongly and positively correlated with that from the lysimeter, eddy covariance, and a soil water budget approach; the slope of regression for SR vs. lysimeter was 0.95 with an R2 of 0.96 compiled across the two years. ET measured with the various techniques responded similarly to changes in the microclimatic conditions (i.e. day to day variability) and when water was withheld from the entire vineyard for an extended period. A stress index calculated using reference and actual ET from SR and lysimetry was correlated to leaf water potential, stomatal conductance, and volumetric soil water content measurements. Our results suggest that the new SR method can be used for as a low cost tool to provide growers with field-specific estimates of crop water use and stress for irrigation management without the need for calibration.