Technical Yearbook 2024

lower compared to levels in September 2019 (Table 1). There were no general trends in the element contents of the permanent wood of grapevines growing in the experimental plot and control sections at LOR1 (Table 3). Acknowledgements • This report is an output of WRC Project K5/2561, entitled “Use of winery wastewater as a resource for irrigation of vineyards in different environments”. This solicited project was initiated, funded and managed by the WRC. The project was co funded by Winetech and ARC. • ARC for infrastructure and resources. • Staff of the Soil and Water Science division at ARC Infruitec Nietvoorbij for their assistance, and in particular Mr. F. Baron for his dedicated technical support. • Backsberg, Madeba, Lutzville Winery and Spruitdrift Winery for permitting the project team to work at their wineries and in their vineyards. Colleagues at the wineries for their assistance and support. • Mr W. Smit from Netafim for advice and designing the irrigation systems.

FIGURE 3. Variation in (A) Na and (B) Cl in the grapevine roots sampled from the 0 - 30 cm and 30 - 60 cm soil depth layers at LOR2.

2019. Interestingly, high levels of Na in the 60 - 90 cm soil layer in the control, i.e. below the root zone, did not seem to have a negative effect on visual grapevine performance.

After two years of irrigation with raw water, the levels of Na, Mn and Fe measured in the permanent wood in July 2021 (Table 2) at the LOR2 experimental plot were substantially

TABLE 1. N, P, K, Ca, Mg, Na, Mn and Fe element contents in the permanent wood of grapevines growing in the experiment plot and control at the LOR2 plot in September 2019. N P K Ca Mg Na Mn Fe (%) (mg/kg) Exp. plot 0.95 0.11 0.52 1.62 0.54 1 400 207 2 773 Control 0.70 0.09 0.53 1.45 0.31 700 99 813 TABLE 2. N, P, K, Ca, Mg, Na, Mn and Fe element contents in the permanent wood of grapevines growing in the experiment plot and control at the LOR2 plot in July 2021. N P K Ca Mg Na Mn Fe (%) (mg/kg) Exp. plot 0.59 0.11 0.42 0.48 0.17 805 47 384 Control 0.50 0.09 0.42 0.65 0.23 686 70 562 TABLE 3. N, P, K, Ca, Mg, Na, Mn and Fe element contents in the permanent wood of grapevines growing in the experiment plot and control at the LOR1 plot in July 2021. N P K Ca Mg Na Mn Fe (%) (mg/kg) Exp. plot 0.56 0.08 0.37 0.63 0.13 182 37 357 Control 0.66 0.07 0.31 0.81 0.15 209 43 244

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TECHNICAL YEARBOOK 2024