EFFECT OF ALTERNATE BEARING ON THE MINERAL NUTRITION IN HAZELNUT

In previous works of this group, the amounts of mineral nutrients hazelnut uptake from the soil were investigated in relation to the different ages of the orchards. The aim of this work is to establish the effect of biennial bearing on orchard macronutrient uptake in order to apply the proper amount of mineral fertilizers. Investigations were conducted in two hazelnut orchards of ‘Tonda Gentile delle Langhe’ (TGL), sited in the Langhe district (Piedmont) for two consecutive years, of which the first (2002) was an ‘on-year’ and the following (2003) was an ‘off-year’. For both years and orchards, three representative trees were chosen for the determination of dry mass from pruning, whole fruit, husks and leaves. Then each of these plant parts was analysed to determine their N, P, K, Ca and Mg composition and to calculate the amount extracted per hectare and per year for a given productivity. Whilst the yield losses between on- and off-bearing years were greater than 70% and 60% for the two orchards, for the same two years the differences in mineral uptake were less than 50%, except for K. In addition, the mineral uptake was significantly different between the two orchards and between plant parts considered. These results may be helpful for fruit growers when calculating adequate quantities and rate of application of mineral elements to be supplied, also considering the different needs of the cultivation in an alternate bearing regime.