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Practical method for measuring vineyard crop coefficients improves irrigation management

The Issue

The irrigation crop coefficient relates vine water requirements to climatic conditions. Having an accurate crop coefficient allows farmers to estimate irrigation requirements accurately based on local weather data. Past UC research has demonstrated that the crop coefficient itself can be estimated based on measurements of the ground area shaded by the vineyard leaf canopy at midday. However, previous methods for measuring the shaded area were not practical for commercial use, limiting the use of important irrigation information.

What Has ANR Done?

A novel method for measuring the canopy shaded area has been developed by Mark Battany, viticulture/soils farm advisor for San Luis Obispo and Santa Barbara counties. The device utilizes a lightweight solar panel as a shade meter, which is read with an inexpensive electronic meter. The method provides accurate measurements of the canopy shaded area with much less effort than previous techniques. The device (dubbed the "Paso Panel") has been adopted for use by some of the largest commercial vineyard operations in the state, and has to date characterized the crop coefficient in hundreds of vineyard blocks. The device has also been used by Battany in local research projects, most recently in the comprehensive evaluation of the irrigation crop coefficient at 84 vineyards in the area east of Paso Robles as part of a three-year irrigation evaluation study. Battany has created a website cesanluisobispo.ucdavis.edu/Viticulture/Paso_Panel, which describes the method and construction, and he has traveled to Argentina to bring the technology to that country as well.

The Payoff

A key step for bringing irrigation information to the commercial grower

Many growers base their irrigation decisions on past experiences or guesswork, rather than data, because a practical method for measuring an accurate irrigation crop coefficient hasn't been available. The novel 'Paso Panel' effectively fills this information gap. Using the device, growers and irrigation managers can determine accurate vine irrigation crop coefficients based on the particular conditions in their own vineyards. They can now use this more accurate information to manage irrigation systems more efficiently and to further optimize winegrape quality.


Supporting Unit:

San Luis Obispo and Santa Barbara Counties
Mark Battany, (805)781-5948, mcbattany@ucdavis.edu