FERTILISER GUIDELINES FOR THE WINE INDUSTRY

In proportion to wine grapes, Magnesium is also taken up to a greater extent by rootstocks. No specific Mgsoil norms or fertilisation is recommended however, due to the fact that a Mgdeficiency is readily manifested by very characteristic leaf symptoms, before vine performance is negatively affected. Intervention by means of Mg-sulphate applications can therefore take place in time if such symptoms are indeed observed. NURSERIES Few experimental results with regard to grapevine nursery fertilisation are avail able locally and internationally and in the past, practical knowledge was mainly relied upon as guidelines. There is not however, a good correlation between nursery success and fertilisation according to this approach. In Wellington, indications have been found that the increase of dry material for grafted vines in a nursery is comparable with cane productions in rootstock mother blocks. Using this as point of departure, nursery fertilisation can be similar to rootstock fertilisation, but at higher amounts due to the intense irrigation and subsequent leaching that occur in nurseries. Seasonal guideline amounts of N, P and K are presented in Table 25. In the case of solid fertilisers, LAN is preferred as N-carrier as it contains lime which serves as source of Ca, as well as single superphosphate as P-carrier because it contains gypsum which serves as source of both Ca and S, and KCI as K-carrier because CI is also an essential nutrient element and not harmful

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