FERTILISER GUIDELINES FOR THE WINE INDUSTRY

C onsiderable research results and general information are available regarding the role and function that certain nutrient elements play in the physiological and/or biochemical processes of the grapevine. The role and function of the most important macro- and micro- elements in the grapevine are discussed in Chapter 5. The majority of the nutrients as single elements or as a group has an impact on berry growth and composition in a direct or indirect way. In a direct way, it is about whether the nutrient elements are present in a deficient or excess situation in the soil, grapevine and/or grapes. A deficiency of nutrients can be detrimental for the physiological and/or biochemical processes in the grapevine, while an excess can be toxic. The deficiency of a specific nutrient element occurs when limited uptake of that nutrient element takes place, and it usually occurs when there are low levels of the element in the soil or insufficient water in the soil for uptake. It is also important to remember that nutrient uptake is very dependent on the soil pH which determines the availability of the element, and the ideal soil pH for good uptake is 5.5-6.5. The indirect relationship involves the growth of the grapevine which is negative ly or positively affected by a deficiency or excess of the nutrients. The vigour and the management thereof determine the canopy characteristics and light relationship of the canopies. The exposure of the bunches, together with the efficacy of the canopy has a big influence on the ultimate grape composition and subsequent wine quality and wine sensory characteristics. There are few specific studies however, with the possible exception of nitrogen, and to a lesser extent potassium, that compare the direct relationship between nutrient levels in the berry and wine sensory characteristics. In contrast, the influence of location of a vineyard, or terroir – which is the combination of the climate, topography and soil type of a specific vineyard or region – whether on the wine style or wine sensory characteristics, are rela tively well studied. Subsequently, the following are a few findings from local as well as interna tional literature with regard to the relationship of specific nutrient elements to wine quality and/or wine sensory characteristics:

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