Travels with Penelope

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September 28, 2015 Wine-Water News From UCDavis


This is the month for news from UCDavis. My partner forwarded another email with news of the latest research on winery wastewater. Again, I could not resist sharing.


Making wine requires water beyond what it takes to grow grapes. There

are bottles to wash, barrels to scrub and floors to clean. But what

if the water left over from all that cleaning was treated and reused

to irrigate vineyards? It sounds like a promising practice,

especially during a drought, but would it hurt the vines, the soil or

even the wine?

To find out, scientists at the University of California, Davis,

assessed winery wastewater samples monthly over two years at 18

wineries in the Napa and Lodi regions of California. In two recently

published studies, they conclude that, under the right conditions,

winery wastewater is a viable water source to irrigate vineyards.

The research provides the first data to support the California wine

industry’s reuse of treated winery wastewater, and it describes

recommended conditions for the practice, with a key focus on salinity


“This is a good baseline data set to look at and say, ‘Now we know

what’s in our wastewater and what we can do to deal with it before we

put it on the grapes,'” said lead author and UC Davis researcher Maya

Buelow. “Vines are a high cash crop, and growers need to proceed with

caution and gather site-specific soil and wastewater data, but there

are wineries successfully doing this.”

Salt water solution?

The researchers learned that most wineries in the study were already

doing a good job of treating their wastewater through a series of

retention ponds and other treatment systems. Salts, however, remain a


Salt concentrations affect how water moves through the soil. Salts

are usually introduced into the wastewater by cleaning agents, and

they are not removed by treatment systems.

However, the study found that levels of salts at the wineries were

usually below thresholds for most wine grape rootstocks and soil

salinity hazards.

There’s also a trend within the wine industry to switch from

sodium-based to potassium-based cleaners. The study examined the

risks and benefits of such a shift for specific soil types. The

scientists emphasize that further research is needed to develop best

management guidelines, but their results indicate that:

* Soils dominated by montmorillonite, a clay mineral, could benefit

from shifting to potassium-based cleaners.

* Both types of cleaners may negatively affect soils dominated by


* Neither type of cleaner reduced infiltration rates in soils with

kaolinite, also a clay mineral.

Not just grapes

“This is very applicable to nearly every agricultural system out

there,” Buelow said. Many other segments of the food industry produce

significant amounts of wastewater, such as dairy, pig, poultry and

food processing operations. “There are opportunities for them to

reuse wastewater, as well,” she said.

The winery wastewater survey was published in the American Journal of

Enology and Viticulture and funded by the Kearney Foundation of Soil

Science. Co-authors include Kerri Steenwerth, Lucas Silva and Sanjai

J. Parikh of UC Davis.

The salinity and soil study was published in the journal Agriculture

Water Management. It was funded by the Kearney Foundation, as well as

the Henry A. Jastro-Shields Scholarship, and co-authored by

Steenwerth and Parikh.

1 Comment

  1. Dear Penelope, It’s always so wonderful to read of your insights and travels. Thank you so much for your wonderful writings! As ever, Bella

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