This field trial aimed to investigate the effect of re-using winery wastewater for irrigation, on the chemical properties of a sandy soil. A Cabernet Sauvignon vineyard grafted onto R99 on sandy alluvial soil in the Breede River Valley region, South Africa was used. Micro-sprinklers were used to apply irrigation.
- Vines were irrigated at 50% PAW;
- Winery wastewater was diluted with river water to different COD (Chemical Oxygen Demand) levels and used to irrigate the vineyard;
- The control was irrigated using river water;
- Soil pH, EC (Electrical conductivity), sodium (Na), potassium (K), carbon (C), magnesium (Mg) and Calcium (Ca) were measured before and after the treatments;
- Details about the cover crops and irrigation strategy can be found in the article.
- The less diluted the wastewater, the more K+ and Na+ accumulated in the soil over the season. Increased K+ in the soil, if absorbed by the vine, can negatively impact wine color stability;
- The wastewater did not contain enough organic matter to affect soil organic carbon levels or yield;
- Soil calcium or magnesium levels were not affected;
- Irrigating with winery wastewater did not have any effect apart from the accumulation of elements, especially potassium and sodium. This accumulation might be greater in vineyards with heavy soils or areas with low winter rainfall. In this case, it could be detrimental to soil physical conditions or growth and yield of vines or may pollute water resources during the rainy season.
SIGNIFICANCE OF THE STUDY:
The study only addressed the suitability of using winery wastewater for the irrigation of grapevines in a sandy soil under one set of climatic conditions. Future research should focus on the use of winery wastewater for the irrigation of different soil types in different climatic regions.
C.L. Howell, P.A. Myburgh, E.L. Lategan, J.E. Hoffman. Effect of Irrigation Using Diluted Winery Wastewater on the Chemical Status of a Sandy Alluvial Soil, With Particular Reference to Potassium and Sodium. S. Afr. J. Enol. Vitic., Vol. 39, No. 2, 2018, p284-296 http://www.journals.ac.za/index.php/sajev/article/view/3171