Browsing by Author "Hoogendijk, Karla"
Now showing 1 - 1 of 1
Results Per Page
- ItemSoil and grapevine responses to irrigation with treated municipal and winery wastewaters(Stellenbosch : Stellenbosch University, 2019-04) Hoogendijk, Karla; Hoffman, J. E.; Myburgh, P. A.; Stellenbosch University. Faculty of Agrisciences. Dept. of Soil Science.ENGLISH ABSTRACT: In recent years, water scarcity and the ongoing drought have had serious implications for the agricultural industry in the Western Cape. The present study investigated the sustainability of two different types of wastewater for use as alternative irrigation water for grapevine production. The first objective was to assess the long-term effects of treated municipal wastewater irrigation on soils and grapevines in commercial vineyards in the Coastal region. The second objective was to investigate the use of in-field fractionally applied winery wastewater with raw water for grapevine irrigation under different climatic conditions. To assess the impact of treated municipal wastewater irrigation on soil and grapevines, a long-term trial was conducted in commercial vineyards in the Coastal region of the Western Cape. Cabernet Sauvignon and Sauvignon blanc grapevines were irrigated using treated municipal wastewater from the Potsdam wastewater treatment works for 11 years. Grapevines were either rainfed (RF), irrigated with treated municipal wastewater via a single dripper line (SLD) or received twice the volume of wastewater via a double dripper line (DLD). Irrigation using treated municipal wastewater increased soil pH and electrical conductivity (ECe). Furthermore, an accumulation of chloride (Cl-) was observed in the topsoil, probably due to the chlorine-disinfection process that is carried out as part of the treatment process at the wastewater treatment works. Appreciable amounts of sodium (Na+) and potassium (K+) also accumulated in the topsoil due to wastewater irrigation. However, this did not result in enhanced uptake by grapevines. The near-saturation hydraulic conductivity (Kns) at the surface of the soil decreased as the ECe in the topsoil increased, with the lowest Kns recorded for the DLD treatments. The irrigation reduced water constraints throughout the growing season compared to RF conditions, particularly in the case of Cabernet Sauvignon. Consequently, the SLD and DLD grapevines produced stronger vegetative growth and higher yields compared to RF. The present study indicated that, with proper management, grapevines can be irrigated successfully using treated municipal wastewater. Previous research has indicated that soil type and winter rainfall have a pronounced effect on salt accumulation where winery wastewater is used for irrigation. The present study investigated the short-term effects of irrigation using in-field fractionally applied winery wastewater with raw water on different soil types under different climates. Suitable experiment sites were identified in the Coastal, Breede River and Lower Olifants River wine production regions, due to their vast difference in climate. Within each region, two plots of differing soil textures were selected. One season of irrigation using fractionally applied winery wastewater with raw water did not have a pronounced effect on soil ECe or soil organic carbon content (SOC). Variable amounts of plant nutrients were supplied to grapevines via the irrigation water. High K+ concentrations in the wastewater resulted in an accumulation in the soil and a subsequent increase in extractable potassium percentage (EPP´). Under the prevailing conditions, irrigation using in-field fractionally applied winery wastewater did not have adverse effects on grapevine vegetative growth, yield or grape juice characteristics. However, further research is needed to assess the sustainability of this particular practice over the long-term.