Globally, medium to large wineries generate more than 1.5 million litres of wastewater annually, whereas small wineries generate less than 1.5 million litres annually.1 This wastewater can be used to irrigate crops to reduce energy use and treatment costs. However, irrigation with winery wastewater needs to be optimised to minimise leaching, whilst maximising nutrient removal by means of a catch crop is a necessity.
Introduction
In a previous study investigating the use of diluted winery wastewater for vineyard irrigation, Avena strigosa cv Saia (oats) and Pennisetum glaucum cv Babala (Pearl millet) removed significant amounts of K from a sandy soil, whilst generating additional income.2 These species, however, consumed substantial amounts of N whereas the concentrations of Na removed were negligible. Additional N fixing crops and grain crops adapted to soils with more than 4% clay that reach their peak growing period during the time that wineries produce the highest volumes of wastewater need to be identified. Therefore, the objective of the project was to identify fodder producing crops that would intercept sufficient K (and Na) applied via irrigation with diluted winery wastewater on loamy sand to sandy clay loam soils in both open land and a vineyard. The selected fodder producing crops should minimise/prevent leaching and accumulation of especially K in these soils and should not have a negative impact on grapevine performance and wine quality. In this specific article, the irrigation application and water quality will be presented.
The characteristics of the catch crops to be evaluated in the study were described previously.3 Annual grasses included in the evaluation were Pearl millet, Barsweet sorghum and Eragostris teff. Perennial grasses included in the study were Weeping lovegrass, Vetiver grass and Bottlebrush grass. Annual broadleaf crops include Fodder radish. Perennial broadleaf species include Chicory. In the study, the annual legumes included were Cow peas and Dolischos beans.
Methods
Diluted winery wastewater was applied to open land on the Nietvoorbij research farm where 10 different fodder producing catch crops were compared to a control where no catch crop was cultivated in the summer (Table 1). In the vineyard experiment, combinations of three different fodder producing summer catch crops and two winter cover crop treatments were compared to a control (Table 2). In this instance, catch crops were not cultivated in the control treatment during the summer, but there were still two winter cover crop treatments. Pictures of the catch crops are shown in Figure 1.
FIGURE 1. Catch crops used on the open land and in the vineyard.
Application of diluted winery wastewater
The irrigation systems only became operational at the end of February 2017, therefore the catch crops could not be sown pre-harvest in the vineyard. The catch crops on the open land were sown in March 2017. Irrigations of 7.7 mm were applied to the open land at approximately weekly intervals. The average COD of the irrigation water applied was 2 994 mg/L and the EC was 106 mS/m.
The volume of diluted winery wastewater applied to the open land in 2018 was increased to approximately 15 mm per week. The same amount of diluted winery wastewater was applied to the vineyard. Irrigations were applied to the open land and vineyard at approximately weekly intervals. The average COD and EC of the irrigation water applied was 3 138 mg/L and 150 mS/m, respectively. The average Na, K, Ca and Mg content of the irrigation water applied was 94 mg/L, 155 mg/L, 109 mg/L and 17 mg/L, respectively. As expected, the winery wastewater had high concentrations of K, Ca and Na. This is similar to previous findings.4,5,6
No winery wastewater was available until 25 February 2019. Given that 16 mm of rain fell on 10 and 11 March, the irrigation of the open land and vineyard only commenced in late and mid-March, respectively. The open land was irrigated on 27/03/2019, 03/04/2019 and 28/05/2019. The vineyard was irrigated with diluted winery wastewater on 19/03/2019, 28/03/2019 and 02/04/2019. The average COD and EC of the irrigation water applied to the open land was 1 212 mg/L and 151 mS/m, respectively. The average COD and EC of the irrigation water applied to the vineyard was 1 533 mg/L and 214 mS/m, respectively. The average Na, K, Ca and Mg content of the irrigation water applied to the open land was 107 mg/L, 318 mg/L, 66 mg/L and 18 mg/L, respectively. The average Na, K, Ca and Mg content of the diluted winery wastewater applied to the vineyard was 148 mg/L, 519 mg/L, 94 mg/L and 23 mg/L, respectively.
Irrigation of the open land and vineyard commenced in mid-March 2020. Irrigations were applied to the open land and vineyard on 19/03/20, 11/05/20, 20/05/20 and 26/05/20. The average COD and EC of the irrigation water applied was 2 570 mg/L and 186 mS/m, respectively. The average Na, K, Ca and Mg content of the irrigation water applied was 83 mg/L, 332 mg/L, 98 mg/L and 15.9 mg/L, respectively.
The concentrations of each element applied via the diluted winery wastewater in the vineyard were used to calculate the amount of each element applied. In the 2017/18 season, 190 kg/ha, 133 kg/ha, 21 kg/ha and 115 kg/ha of K, Ca, Mg and Na, respectively, were applied. In the 2018/19 season, 238 kg/ha, 43 kg/ha, 10 kg/ha and 68 kg/ha of K, Ca, Mg and Na, respectively, were applied via the diluted winery wastewater to the vineyard. In the 2019/20 season, 325 kg/ha, 95 kg/ha, 15 kg/ha and 79 kg/ha of K, Ca, Mg and Na, respectively, were applied.
Conclusions
The diluted winery wastewater used for irrigation of the open land and vineyard contained high levels of K. Consequently, substantial amounts of K were applied via the irrigation with diluted winery wastewater. This could supply more than adequate K to the vineyard if grape yield amounts to 10 t/ha. The winery wastewater also contained high levels of Ca and Na and substantial amounts of these elements were also applied to the open land and vineyard via the diluted winery wastewater irrigation.
Abstract
Globally, medium to large wineries generate more than 1.5 million litres of wastewater annually, whereas small wineries generate less than 1.5 million litres annually. Irrigation with winery wastewater needs to be optimised to minimise leaching, whilst maximising nutrient removal by means of a catch crop is a necessity. The objective of the project was therefore to identify fodder producing crops that would intercept sufficient K (and Na) applied via irrigation with diluted winery wastewater on loamy sand to sandy clay loam soils in both open land and a vineyard. Diluted winery wastewater was applied to open land on the Nietvoorbij research farm where 10 different fodder producing catch crops were compared to a control where no catch crop was cultivated. In the vineyard, combinations of three different fodder producing summer catch crops and two winter cover crop treatments were compared to a control. Catch crops were not cultivated in the control treatment during the summer, but there were still two winter cover crop treatments. The diluted winery wastewater applied to the open land and vineyard contained high levels of K which could supply more than adequate K if grape yield amounts to 10 t/ha. Substantial amounts of K, Ca and Na were also applied via the irrigation with diluted winery wastewater.
Catch crop, soil and grapevine responses, as well as wine quality, will be presented in subsequent articles.
Acknowledgements
- The project was funded by 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
- Van Schoor, L.H., 2005. Guidelines for the management of wastewater and solid waste at existing wineries. Winetech, winetech.co.za.
- Fourie, J.C., Theron, H. & Ochse, C.H., 2015. Effect of irrigation with diluted winery wastewater on the performance of two grass cover crops in vineyards. S. Afr. J. Enol. Vitic. 36, 210-222.
- Fourie, J.C., Howell, C.L. & Masekwana, N., 2021. Selection of grass and broadleaf crops as catch crops where winery wastewater is used for irrigation: A review. Afr. J. Enol. Vitic. 42, 10-17.
- Myburgh, P.A. & Howell, C.L., 2014. The impact of wastewater irrigation by wineries on soil, crop growth and product quality. WRC Report No. 1881/1/14. ISBN 978-1-4312-0591-2.
- Mulidzi, A.R., 2016. The effect of winery wastewater irrigation on the properties of selected soils from the South African wine region.D. dissertation. Stellenbosch University, Private Bag X1, 7602 Matieland (Stellenbosch), South Africa.
- Howell, C.L., Myburgh, P.A. & Hoogendijk, K., 2022. Use of winery wastewater as a resource for irrigation of vineyards in different environments. WRC Report No. 2651/1/22. ISBN 978-0-6392-0341-6.
For more information, contact Carolyn Howell at howellc@arc.agric.za.
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