Focus on irrigation: from natural resource to scarce commodity – Vinpro

The old adage, “You don’t miss your water until the well runs dry” rings particularly true now we’re in the midst of a drought. Waterwise changes must be implemented and sustainable. 

The ongoing drought means that increasing focus is being put on the reuse of water in the wine value chain, and more specifically on the reuse of winery water for the irrigation of vines. But before water can be reused for irrigation, several aspects must be taken into account. In some cases water may simply not be fit for irrigation.

“When reusing water for irrigation, it’s important that it doesn’t damage the soil,” Dr Philip Myburgh of the ARC Infruitec/Nietvoorbij cautions. “Also, the water must not have a negative effect on the growth or yield of the vine. Finally the wine quality must not be affected.”

Dr Myburgh explains that winery water destined for vineyard irrigation has to be regularly analysed for chemical oxygen demand (COD), potassium, sodium and electrical conductivity (EC). If the COD is too high, excessive accumulation of organic material in poorly aerated soil can lead to an unfavourable root environment. Too high levels of sodium could be toxic to the grapevine. Furthermore, if the sodium adsorption ration (SAR) is too high, it could have negative effects on the soil physical status. High potassium levels could lead to high pH in wine which could cause colour instability in red wine. The EC (which gives an indication of salts in water) is also important, as high salt levels will increase the osmotic potential of soil water. This may impede water uptake by roots.

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