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Monday, July 16, 2012

Ways to Measure Vineyard Water Status

The heat wave was broken on Sunday evening, but it was 15 days from rain event to rain event and I thought that I should be familiar with how to measure the vine water status in case irrigation becomes a necessity. The occurrence of drought-like conditions during the pre-veraison stage of grape development, may be beneficial to grape quality but if the drought continues, then knowing how to tell if the vine is stressed becomes important.
You can either measure the water status in the soil or in the grapevine itself:
    Devices for Measuring Soil Moisture Status1:
  • Tensiometer
  • Gypsum block
  • Irrometer
  • Soil dielectric measurements:
    • Time Domain Reflectometry (TDR)
    • Ground Penetrating Radar (GPR)
    • Frequency Domain Reflectometry (FDR or capacitance)—most common
  • Neutron Scatter
    Device for Measuring Vine Water Status
  • Pressure chamber (aka pressure bomb)
There are several excellent articles that can be accessed online regarding how to measure the vine water status. Chapter 10: Grapevine Water Relations and Vineyard Irrigation comes from North Carolina and from Practical Winery and Vineyard Journal is an article entitled Three most common methods---measuring vine water status. This article explains when and how to take a pressure chamber reading.
An excellent pictorial guide to using the pressure chamber can be found at this site: Measuring Leaf Water Potential in Wine Grapes
1. Summary of measurement methods taken from VID257 Viticulture for Winemakers, UC Davis online course.

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