What causes variability?
Nutrients, slope, competition, water
Variability within different sections of a vineyard block, or even along different sections of individual rows, can have many different causes. Differences in soil types (e.g. gravel pockets) affect the availability of certain nutrients and how much water can be held in the soil. In sloped vineyards, the vines at the lowest end of the irrigation lines usually receive extra water as the lines drain out once the water is shut off. Neighboring vines or other plants (e.g. fenceline trees or ground cover) can soak up additional nutrient and water with their vast root systems. No matter the cause, though, the result will almost always be visible as either increased or decreased vine vigour.
Yu R, Brillante L, MartĂnez-LĂĽscher J and Kurtural SK (2020) Spatial Variability of Soil and Plant Water Status and Their Cascading Effects on Grapevine Physiology Are Linked to Berry and Wine Chemistry. Front. Plant Sci. 11:790. doi: 10.3389/fpls.2020.00790
How are growers hacking existing irrigation systems to mitigate crop variability?
Multiple drip lines, Manual partitioning valves, Extra emitters that need to be capped when their extra water is not needed
In most grape and tree fruit growing regions in which irrigation is needed for plant survival and business-appropriate yields, water can be used as a tool to mitigate plant variability. This is achieved by giving plants with below-target vigour extra water and withholding it from those with excessive vigour. Generally, irrigation systems are designed to deliver the same amount of water to each plant in the system. Any required changes mean extra costs to the grower and most of them require significant amounts of extra labor to execute. Some growers add additional irrigation lines to each row.
We have seen as many as three irrigation lines per row in high-end vineyards in California’s Napa Valley - one for general irrigation and fertigation purposes, a second with emitters only for any struggling plants, and a third line with emitters only for replants.
Another technique used is the installation of manual shutoff valves within rows that allow growers to isolate certain sections of those rows. One challenge here is that driplines are fed from one end only and sections in the middle or at the beginning of the row cannot be isolated as the end will not receive water if they are. Having to remember to and then go turn isolation valves on and off by hand is time- and brain-consuming (= expensive).
A third approach used in vineyards is adding additional emitters into one drip line in weak zones. This works great to add extra water but can become challenging once low vigor zones increase in vigor and don’t need the extra water anymore or when specific amounts of nutrient are supposed to be added to each plant via fertigation. Most emitters can be capped by hand once installe or removed and the hole closed with a dummy plug but this is an incredibly labor-intense process.
The next generation irrigation tech solving crop variability in vineyards and orchards
Having successfully proven the technology for multiple seasons with industry leaders like E&J Gallo, Arterra, and UC Davis, Verdi has distinguished itself as the first and only commercially available solution for variable rate irrigation in specialty crops.
Verdi retrofits smart valves along irrigation lines to split existing irrigation zones into smaller zones according to vigor maps produced from its software. These discrete zones give growers the flexibility to increase irrigation and fertigation in areas of low vigor while restricting them in areas of high vigor. The valves also contain flow meters to check for line leaks and breaks -another first for the industry.
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Arterra Wines, Canada’s largest wine company, implemented Verdi’s precision management system with dramatic results. It reduced water usage by 60% in some zones and resulted in all grapes across the vineyard ripening at the same time — allowing a single harvest pass. Grape quality also improved, allowing Arterra to upgrade one zone from $12 per bottle to a more premium price tier of $30 per bottle, thus increasing revenue by 8% per acre.
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The research director at a top three global wine company assessed its experience with Verdi’s solution as “the industry leader in variable rate irrigation technology”. The affordable controllers easily attach to a vineyard’s existing drip lines, taking less than two minutes each to install, and existing irrigation infrastructure remains in the hands of the growers.
