Magnesium supply of the vineyards in the Balaton - Highlands

The physiological importance of magnesium is well known. Although vines need this nutrition in macro element quantities, its replenishment in the fertilisation system of vineyards is not widespread in Hungary. Over the past years deficiency symptoms which could be attributed to a deficiency in magnesium were visually noticed on the foliage in vineyards in the traditional wine regions located on the northern shore of the Balaton. This phenomenon raised the possible need for magnesium replenishment to be included in the production technology.In 1998 the Ministry of Agriculture and Rural Development Research Institute for Viticulture and Aenology, Badacsony recognised that this subject was topical and set up field trials for the use of magnesium fertilizer, within the frame of which various doses, methods of administering magnesium replenishment (soil and foliage treatment) were carried out annually using Epsom salt (MgSO4 x 7H2O). On the basis of the results of the three years of the experiment it can be ascertained that: significant increase in the quantity of the bunch yield could be seen with the "higher dosage" soil treatments (30-40 kg/ha). Foliage treatment in itself did not increase the production yield. The effect of the use of magnesium fertilizer on the quality of the must and wine depends on the vintage. In two out of the examined years data regarding the must degree showed a rateable increase where soil treatment was applied in higher doses. During the organoleptic grading of the experimental wines the judges sensed a positive difference in two out of the three years in the quantity and quality of the flavour and aroma materials present, to the complement of the magnesium treatments. Data concerning soil and leaf analysis shows unambiguously that on the trial area the relative magnesium deficiency, which can be traced back to the stockpiling of K fertilizer, causes the deficiency symptoms. When visually observing prior to harvest the deficiency symptoms, which can be traced back to the visible magnesium deficiency on the foliage, soil applications of the larger dose (30-40 kg/ha) gave favourable, lower percentage values. Here too no favourable effect of just foliage fertilizer application was observed. Summarising our results to date it can be ascertained that magnesium fertilizer application, depending on the applied dose and form, effected grape bunch yield, the sugar content of the must and the sensual values of the wine in a positive manner, and the deficiency symptoms visible on the foliage were also significantly reduced after each application.