South Africa Wine Technical Yearbook 2025

FIGURE 2. The effect of municipal water and winery wastewater (WWW) on the phosphatase activity (μg p-nitrophenol g -1 2h -1 ) in four soils in the (A) 0-10 cm soil layer and (B) 10-20 cm soil layer in the third simulated season, as well as in the (C) 0-10 cm soil layer and (B) 10-20 cm soil layer in the fourth simulated season. Values in the same data set, that are followed by the same letter, do not differ at p = 0.05.

TABLE 1. Pearson correlation coefficients (r) for urease, phosphatase and β-glucosidase activities. (n = 95). Enzymes correlated r p Urease β-glucosidase 0.4294 < 0.0001 Urease Phosphatase 0.1496 0.1478 Glucosidase Phosphatase 0.3740 0.0002

shale > Rawsonville sand > Lutzville sand. β-glucosidase β-glucosidase activities in the 0-10 cm soil layer tended to be greater than those in the 10-20 cm soil layer in all four soils (Figure 3). Average β-glucosidase activity was generally lower in the third simulated season compared to the fourth one. β-glucosidase activities were higher in the soils irrigated with diluted WWW compared to those irrigated with municipal water in all four soils. The β-glucosidase activities in the experimental soils decreased in the sequence: Stellenbosch shale > Stellenbosch granite > Rawsonville sand > Lutzville sand. Correlations and discussion Urease activity correlated significantly with β-glucosidase activity but not with phosphatase activity (Table 1). β-glucosidase and phosphatase activities correlated significantly but not strongly.

to methods described previously. 15 Enzyme activities were expressed on a moisture-free basis. Soil moisture content was determined from the loss in weight after drying at 105°C for 24 hours. Urease activities in the 0-10 cm soil layer exceeded those in the 10-20 cm soil layer in all four soils (Figure 1). Average urease activity was generally greater in the third simulated season compared to the fourth one. Urease activities were higher in the soils irrigated with diluted WWW compared to those irrigated with municipal water in all four soils. Averaged over the two simulated seasons, water type and soil depth, Results Urease

urease activity in the soils decreased in the sequence Stellenbosch shale > Stellenbosch granite, Rawsonville sand > Lutzville sand (data not shown). Phosphatase Phosphatase activities in the 0-10 cm soil layer were similar to those in the 10-20 cm soil layer in all four soils (Figure 2). Average phosphatase activity tended to be greater in the third simulated season compared to the fourth one. Phosphatase activities were lower in the soils irrigated with diluted WWW compared to those irrigated with municipal water in all four soils. All-treatment average phosphatase activities decreased in the sequence: Stellenbosch granite > Stellenbosch

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TECHNICAL YEARBOOK 2025