FERTILISER GUIDELINES FOR THE WINE INDUSTRY

Conradie (1994) proposed the following empirical adjustments: 0-1 % organic material: no adjustment 1-2 % organic material: apply 80 % of the calculated requirement 2-3 % organic material: apply 60 % of the calculated requirement 3-4 % organic material: apply 40 % of the calculated requirement

Adjustments made according to this approach generally result in realistic recommendations. Later research by Smuts (2001), however, led to the proposal of an amended formula:

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H – [(7 – field pH KCl ) x %C x 0.202]

At this stage, it would seem however, that recommendations made according to these two approaches are comparable with each other. Further research is currently being conducted. CHOOSING THE TYPE OF LIME: As calcium and magnesium constitute an integral part of a grapevine’s nutri ent requirements, it is critically important that the vine should not experience deficiencies of these two elements. Liming before planting is undoubtedly the best way to prevent calcium and magnesium deficiencies. Many lime products are available, like inter alia agricultural lime, dolomitic lime, slaked and unslaked lime. Gypsum is not a lime product, as it is a neutral salt and does not contribute to an increase in soil pH. Gypsum is used as a source of Ca and/or S, especially on saline soils to displace sodium (Na). In order to obtain the desired result in the soil as well as the desired reaction of the grapevine thereto, it is important that the neutralisation ability and re activity of the available lime products, as well as the source of the products,

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