WINETECH Technical Yearbook 2021

HOW DO WE INTEGRATE THESE PRINCIPLES IN THE SOUTH AFRICAN WINE INDUSTRY? Variation of soil properties can differ within the same block, which then will require different management systems and decisions. Before the introduction of precision farming principles, producers had no other choice but to manage blocks according to conventional average conditions, with the eye on optimal average production from their inputs. The management of average conditions will probably prove to be inherently ineffective, as the soil limitations in one part of the block is not addressed, while in another part of the block it could lead to excessive inputs. This management approach can thus result in antagonistic effects (decreasing availability of elements to the plant due to interaction between elements) and also cause environmental pollution. To illustrate: figure 2 indicates the pH (KCI) distribution within blocks (with colours of green being optimal). These specific blocks were overlimed with calcite and underlimed with dolomite which led to the pH already edging high. No further lime additions can be recommended. In effect the high calcium levels will suppress other elements, like manganese, phosphate, zinc, magnesium, iron and potassium. As seen in

FIGURE 2. Indicates pH (KCI) distribution.

FIGURE 3. Indicates the magnesium in mg/kg.

FIGURE 4. Indicates the varying correction of magnesium.

FIGURE 5. Indicates the potassium in mg/kg.

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