Technical Yearbook 2024

respectively. The average Na, K, Ca and Mg content of the raw water was 25 mg/L, 2 mg/L, 7 mg/L and 6 mg/L, respectively. The average SAR and PAR of the raw water was 1.65 and 0.08, respectively. In the Lower Olifants River region, the average pH, EC and COD of the winery wastewater to the LOR1 experimental plot over four seasons was 6.27, 3.07 dS/m and 5 546 mg/L, respectively. The average Na, K, Ca and Mg content of the winery wastewater was 77 mg/L, 557 mg/L, 327 mg/L and 22 mg/L, respectively. The average SAR and PAR of the winery wastewater was 1.26 and 5.22, respectively. The average pH, EC and COD of the raw water over four seasons was 6.78, 0.19 dS/m and 9 mg/L for the LOR1 experimental plot, respectively. The average Na, K, Ca and Mg content of the raw water applied to this experimental plot was 22 mg/L, 2 mg/L, 5 mg/L and 4 mg/L, respectively. The average SAR and PAR of the raw water was 1.71 and 0.10, respectively. The average pH, EC and COD of the winery wastewater applied to the LOR2 experimental plot over two seasons was 5.75, 3.21 dS/m and 8 535 mg/L, respectively. The average Na, K, Ca and Mg content of the winery wastewater was 240 mg/L, 402 mg/L, 184 mg/L and 26 mg/L, respectively. The average SAR and PAR of the winery wastewater was 5.12 and 4.91, respectively.The average pH, EC and COD of the raw water applied to the LOR2 experimental plot over two seasons was 6.65, 0.20 dS/m and 28 mg/L, respectively. The average Na, K, Ca and Mg content of the raw water was 19 mg/L, 2 mg/L, 4 mg/L and 5 mg/L, respectively. The average SAR and PAR of the raw water was 1.49 and 0.11, respectively. The average pH and EC of the raw water applied to the LOR2 experimental plot after the termination of the in-field fractional use (augmentation) of winery wastewater with raw water for vineyard irrigation at the beginning of the 2019/20 season was 6.82 and 0.19 dS/m, respectively. The average Na, K, Ca and Mg content of the raw water was 26 mg/L, 3 mg/L, 5 mg/L and 4 mg/L, respectively. The average SAR and PAR of the raw water was 1.67 and 0.13, respectively. Nutrient load The concentrations of each element applied via the in-field fractional use (augmentation) of winery wastewater with raw water for vineyard irrigation were used to calculate the amount of each element applied. On average over four seasons, 259 kg/ha, 38 kg/ha, 15 kg/ha and 71 kg/ha of K, Ca, Mg and Na, respectively, were applied per season to each of the experimental plots in the Coastal region. In the Breede River region, 108 kg/ha, 48 kg/ha, 29 kg/ha and 114 kg/ha of K, Ca, Mg and Na, respectively, were applied per season to each of the experimental plots. On average over four seasons, 844 kg/ha, 496 kg/ha, 56 kg/ha and 225 kg/ha of K, Ca, Mg

Conclusion As expected, grapevines growing in the regions with lower mean annual rainfall required more irrigation. The K and Na levels in the undiluted winery wastewater was substantially higher than that in the raw water. Consequently, the PAR of the undiluted winery wastewater was substantially higher than the raw water. With regard to the refinement of the General Authorisations for wineries, the PAR of the wastewater has not yet been adopted as a quality parameter. Considering that results confirm that winery wastewater contains high levels of K, the use of the PAR of the wastewater should be considered as a further indicator of the wastewater quality. However, further research is needed to refine PAR norms for wastewater quality. Taking above-mentioned into consideration, substantial amounts of additional elements were applied to the vineyard via the in-field fractional use (augmentation) of winery wastewater with raw water for vineyard irrigation. Given that amounts of K applied via the in-field fractional use (augmentation) of winery wastewater with raw water were considerably higher than the grapevine’s requirements, the cultivation and removal of a suitable interception crop during summer might be useful to absorb excessive K. Soil responses to the in-field fractional use (augmentation) of winery wastewater with raw water for vineyard irrigation will be presented in the next article.  and Na, respectively, were applied per season to the LOR1 experimental plot in the Lower Olifants River region. For the LOR2 experimental plot, 958 kg/ha, 470 kg/ha, 79 kg/ha and 631 kg/ha of K, Ca, Mg and Na, respectively, were applied per season. Acknowledgements • This report is an output of WRC Project K5/2561, entitled “Use of winery wastewater as a resource for irrigation of vineyards in different environments”. This solicited project was initiated, funded and managed by the WRC. The project was co-funded by Winetech and ARC. • 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. • Backsberg, Madeba, Lutzville Winery and Spruitdrift Winery for permitting the project team to work at their wineries and in their vineyards. Colleagues at the wineries for their assistance and support. • Mr. W. Smit from Netafim for advice and designing the irrigation systems.

References https://www.wineland.co.za/in-field-fractional-use-of-winery-wastewater-with-raw-water-part-2/

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

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TECHNICAL YEARBOOK 2024