Handbook for Irrigation of Wine Grapes in South Africa

D

D

210 240 270 300 330

210 240 270 300 330

i e

Chapter 5

200 winery wastewater will not necessarily leach more readily from sandy soils than heavier soils under field conditions. According to Mulidzi (2016), irrigation with diluted winery wastewater did not increase soil organic C, compared to irrigation with clean water under the prevailing conditions, irrespective of the clay content (data not shown). It was concluded that breakdown of organic material applied via the winery wastewater occurred between irrigations, although the COD level was approximately hundred times higher in the winery wastewater than in the clean water. This emphasizes the importance of effective irrigation scheduling if winery wastewater is used for irrigation. 0 30 60 90 0 00 0 10 0 20 0 30 0 40 Na (cmol (+) /kg) River water 3000 mg  C2D

2 - K (mg/kg)

00

150

River water 3000 mg  C2D

120 150 180 210 240 270 300 330

3 0

3 0

Depth (cm)

Rawsonville sand - 3.3% clay Lutzville sand - 0.4% clay Stellenbosch shale - 21% clay Stellenbosch granite - 13% clay

2 5

2 5

2 0

2 0

1 0 K ex (cmol (+) /kg) 1 5

0 5 1 0 Na ex (cmol (+) /kg) 1 5

0 5

A

0 0

0 0

0

500

1 000

1 500

0

Applied K (kg/ha)

3 0

2 5

2 0

0 5 1 0 Na ex (cmol (+) /kg) 1 5

B

0 0

1 000

1 500

0

200

400

600

/ha)

Applied Na (kg/ha)

FIGURE 5.20. Accumulation of extractable (A) K and (B) Na in four differently textured soils irrigated with winery wastewater diluted to 3 000 mg/  COD over four simulated seasons in a pot experiment under a rain shelter (Mulidzi et al ., 2015b).

IRRIGATION OF WINE GRAPES 133