Technical Yearbook 2024

AUGUST

In-field fractional use of winery wastewater with raw water (Part 1): Plot selection, augmentation and climatic conditions By Carolyn Howell & Reckson Mulidzi Abstract Wine grapes are an important crop in regions such as the Western Cape and the Lower Orange River in the Northern Cape. However, wineries produce large volumes of poor quality wastewater, particularly during harvest. Since water resources are limited, wine grape producers will have to use them judiciously to produce grapes. It is also important that the sustainable use of alternative water sources for vineyard irrigation be investigated. The primary objective of the study was therefore to assess the fitness for use of winery wastewater for irrigation of different soil types with varying rainfall quantities and leaching levels on vineyard performance in terms of yield and quality under field conditions, as well as measuring the change in mainly Na and K status of soils. Experimental plots were selected in three selected production areas in the Western Cape Province, namely the Coastal, Breede River and Olifants River regions. The specific locations were selected due to their vast differences in mean annual rainfall. Within each region, two plots were selected which differed in soil texture. Results of the textural analyses of the selected soils showed that there was a substantial difference in their textural properties. It was therefore expected that they would respond differently to irrigation with winery wastewater. Given that it would be impractical to augment winery wastewater to a pre-determined chemical oxygen demand (COD) level before irrigation, a more practical approach to irrigating the experimental plots was applied. In this regard, the in-field fractional use (augmentation) of winery wastewater with raw water for irrigation was used.

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TECHNICAL YEARBOOK 2024