South Africa Wine Technical Yearbook 2025

FIGURE 2. Temporal variation in soil water content (SWC) in (A) Rawsonville sand, (B) Lutzville sand, (C) Stellenbosch shale, and (D) Stellenbosch granite soils measured in a pot experiment. Arrows indicate when soil chemical status was determined after each of the simulated seasons. “FC” and “RP” indicate field capacity and refill point, respectively.

irrigations. Visual observation revealed that no drainage occurred after irrigations had been applied. Therefore, it can be assumed that no leaching occurred of elements applied via the municipal water or diluted WWW. The foregoing indicated that the lysimetric approach provided an accurate measure of the irrigation volumes required. It is important to note that the pot experiment was completed in approximately two and a half years, whereas it would have taken four years to do the wastewater irrigation in a field experiment.

Conclusions It was possible to subject more than one soil to irrigation with diluted WWW by using a single mix and irrigation infrastructure. Since the pot experiment could be continued under the rain shelter during winter, results were obtained quicker compared to an open field study. Results from the study can form a solid basis for future research on the effect of WWW application on soil. Effects of irrigation with diluted WWW on the chemical status of the four soils in the pot study will be presented in subsequent articles. Acknowledgements • This article i s an output of WRC Project K5/1881, entitled “The impact of wastewater irrigation by wineries on soils, crop growth and product quality”. This solicited project was initiated, funded and managed by the WRC. The project was co-funded by Winetech and ARC. • Goudini Winery for providing wastewater for the research. • ARC for infrastructure and resources. • Staff of the Soil and Water Science division at ARC Infruitec-Nietvoorbij for their assistance, and in particular Mr. F. Baron for his dedicated technical support. 

For more information, contact Reckson Mulidzi at mulidzir@arc.agric.za. Reference https://www.wineland.co.za/winery-wastewater-irrigation-part-4/

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TECHNICAL YEARBOOK 2025