Technical Yearbook 2024

100 120

A

0 20 40 60 80

K ns (mm/h)

RF

SLD

DLD

100 120

B

0 20 40 60 80

K ns (mm/h)

RF

SLD

DLD

100 120

C

0 20 40 60 80

K ns (mm/h)

RF

SLD

DLD

FIGURE 1. Using a mini disk infiltrometer to measure near saturation hydraulic conductivity in a vineyard near Philadelphia.

FIGURE 2. Effect of rainfed conditions (RF) and irrigation with treated municipal wastewater via single (SLD) and double dripper line (DLD) on the near-saturation hydraulic conductivity (K ns ) (suction = 2 cm) of (A) a shoulder, (B) a backslope, and (C) a footslope during the 2017/18 season.

study, a combination of solutions with known SAR and PAR was used to investigate the binding of Na + and K + , and it was concluded that exchangeable sodium percentage (ESP) corresponding to a given SAR was increasingly lowered at higher K + concentrations. 5 Using three soils of contrasting mineralogy packed in soil columns, it was found that soil mineralogy and Na + and K + concentrations in solutions were key factors influencing the soil hydraulic conductivity. 1

Taking the above-mentioned into consideration, the objective of the study was to assess the long-term effects of irrigation with TMW on soil hydraulic conductivity in commercial vineyards in the Coastal region of the Western Cape. Methods The field trial was carried out in full bearing, commercial vineyards on a farm near Philadelphia in the Coastal region of the Western Cape from the 2006/07 until 2017/18 seasons.

Three experiment sites were selected in different landscape positions. The first site was in a Sauvignon blanc vineyard located on the shoulder of a hill. The second and third sites were in two Cabernet Sauvignon vineyards situated on a back- and a footslope, respectively. Details of the characteristics of the vineyards, irrigation treatments and application, as well as an assessment of the water quality and nutrient load was reported previously. 6,7,8 Grapevine water status, vegetative growth and yield, as well as

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TECHNICAL YEARBOOK 2024