Technical Yearbook 2024

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

A

2017/18 4-Year mean

Conclusion Although high amounts of K + , Na + and Cl - were applied via TMW irrigation, it did not result in excessive uptake by the grapevines, causing any negative effects on yield. This suggested that grapevines possess mechanisms to regulate the uptake of ions from the soil solution. Despite the high amounts of salts applied via TMW irrigation, no salinity hazards regarding yield were observed for the irrigated treatments. Given that the irrigation reduced water constraints throughout the growing season compared to RF conditions, particularly in the case of Cabernet Sauvignon, SLD and DLD grapevines produced higher yields compared to RF grapevines. Results showed that the availability of irrigation water (albeit of relatively low quality) in regions where grapevines are usually grown under dryland conditions can increase yield whilst maintaining good fruit quality. Although this study indicated that grapevines can be irrigated successfully using TMW, proper management is required to limit possible negative effects on grapevines and the environment. Soil responses will be presented in a follow-up article. 

pH

RF

SLD

DLD

B

2017/18 4-Year mean

pH

RF

SLD

DLD

C

2017/18 4-Year mean

pH

RF

SLD

DLD

FIGURE 5. Effect of rainfed conditions (RF) and irrigation with treated municipal wastewater via single (SLD) and double dripper line (DLD) on grape juice pH in (A) Sauvignon blanc on a shoulder, as well as Cabernet Sauvignon on (B) a backslope and (C) a footslope during the 2017/18 season compared to the mean for the 2013/14 to the 2016/17 season. Acknowledgements • The project was funded by the Water Research Commission (WRC), Winetech and the Agricultural Research Council (ARC). • ARC for infrastructure and resources. • Staff of the Soil and Water Science division at ARC Infruitec-Nietvoorbij for technical support. References

https://www.wineland.co.za/treated-municipal-wastewater-for-irrigation-part-3/

For more information, contact Carolyn Howell at howellc@arc.agric.za.

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TECHNICAL YEARBOOK 2024