South Africa Wine Technical Yearbook 2025

TABLE 1. Quality characteristics of the municipal water and winery wastewater used for the irrigation of four different soils.

layers, the degree of K + extraction was similar for the four soils with an increase of 0.0002 cmol (+) /kg per kg K + applied. Municipal water irrigation did not affect the soil EPP' (data not shown). In contrast, irrigation with diluted WWW increased EPP' over the four seasons (Figure 2). The EPP' in the 0-10 cm soil layer was slightly higher compared to the 10-20 cm layer with the exception of the Stellenbosch granite soil. In the case of the sandy soils and Stellenbosch shale soil, the EPP' in the 0-10 cm showed a slower increase following the second season (Figures 2A, 2B and 2C). The EPP' in the 10-20 cm layer showed an almost linear increase with applied K + . In the case of the Stellenbosch granite, these trends did not occur as EPP' was comparable in both soil layers (Figure 2D). After the fourth season, EPP' was similar in both layers, which suggested that the granite soil was no longer

Season

Water quality variables

1

2

3

4

Mean

Municipal

pH

7.7 8.3 0.8 7.4 6.3 1.3 0.7

7.5 7.2 0.7 7.2 6.0 1.1 0.7

7.7 9.5 0.9 8.1 6.1 1.5 0.8

6.9 9.3 1.6 8.5 5.3 1.8 0.8

7.4 8.6 1.0 7.8 5.9 1.4 0.8

EC (mS/m) K + (mg/L) Na + (mg/L) Ca 2+ (mg/L) Mg 2+ (mg/L)

SAR

32.6

22.4

18.4

26.0

24.9

HCO 3

-

Winery

pH

5.3

6.0

4.9

5.6

5.4

EC (mS/m) K + (mg/L) Na + (mg/L) Ca 2+ (mg/L) Mg 2+ (mg/L)

94.2 196.1 75.5 14.1

109.8 186.6 114.9 18.0

94.6 204.9 78.7 20.0

119.0 196.4 68.6 22.4

104.4 196.0 84.4 18.6

4.9 4.5

8.4 5.6

6.5 4.0

9.1 4.1

7.2 4.6

SAR

511.3

655.1

438.2

552.9

539.4

HCO 3

-

FIGURE 1. Effect of K + applied via diluted winery wastewater over four seasons on the extractable K + in the 0-10 cm and 10-20 cm layers of (A) Rawsonville sand, (B) Lutzville sand, (C) Stellenbosch shale, and (D) Stellenbosch granite soils. The encircled data point was regarded as an outlier due to experimental error and was not included in the equation. Values designated by the same letter do not differ significantly (p ≤ 0.05).

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TECHNICAL YEARBOOK 2025