South Africa Wine Technical Yearbook 2025

FIGURE 9. Mean monthly rainfall during the study period at a winery near Stellenbosch.

FIGURE 10. Mean monthly wastewater applied during the study period at a winery near Stellenbosch.

per day. The irrigation volumes remained relatively high in winter and began to decline from October to a minimum in December when the soil received only ca . 1 mm wastewater per day. Total irrigation applied during winter, i.e . from April to September, amounted to 2 670 mm, 4 200 mm and 3 820 mm in 2011, 2012 and 2013, respectively. Based on

the foregoing, the soil received the highest irrigation plus rainfall in the winter of 2012, followed by 2013 and then 2011. Similar to Rawsonville, application of high volumes of winery wastewater caused die-back of the grass in the study plot (Figure 11).

FIGURE 11. Disposal of volumes of winery wastewater caused die-back of the grass in the plot at a winery near Stellenbosch.

Conclusions It is important to note that this study represented the worst-case scenario, i.e. the WWW disposal was not carried out in a bigger paddock. The study focused on the real amount of WWW applied per week to the grazing paddocks and its direct environmental impact on a specific site. Consequently, high volumes of WWW were applied on a single plot, particularly in the harvest period and winter. The study confirmed that WWW from a winery near Rawsonville contained high levels of K+ and Na+, whereas WWW from a winery near Stellenbosch contained high levels of K+. These high levels of K+ and Na+ in the WWW reflected the cleaning detergents the specific winery used. Results confirm that WWW composition can vary substantially between wineries. The pH of the WWW tended to be below the legal limit. The study also confirmed that WWW did not comply with national legislations in terms of COD and pH. Soil responses will be presented in the next two articles. 

For more information, contact Reckson Mulidzi at mulidzir@arc.agric.za. Reference https://www.wineland.co.za/winery-wastewater-irrigation-part-1/

13

TECHNICAL YEARBOOK 2025