Assessing nutrient status and removal of hazelnut cultivars in Australian climates

Hazelnut production in the past has been relatively small in Australia; in the last decade, a major expansion has occurred, with considerable plantings in the Riverina (NSW). In 2012, two experimental sites were set up in semi-arid climates (Murray, Riverina) and one in a temperate climate (Central Tablelands); these sites were planted with 15 cultivars. A better understanding of the nutrient status and requirements of the most economically important cultivars is essential under the Australian conditions to ensure target yields. At each site, leaves were collected for two growing seasons from five hazelnut cultivars (‘Barcelona’, ‘Tonda Romana’, ‘Tonda Di Giffoni’, ‘Tokolyi Brownfield Cosford’ and ‘San Giovanni’). From each plot of five trees, 50 leaves were collected in spring and summer from the middle of a new shoot. A further leaf sampling was conducted in autumn from Central Tablelands; here 50 nuts per plot were also collected at harvest for estimation of nutrient removal. Leaf and nut samples were dried and ground, before these were analysed for macro- and micronutrients. The leaf tissue analysis of the five cultivars collected from orchards in summer indicated below, normal, and above normal ranges for most nutrients in the first season. Deficiency or below normal levels were reported for magnesium (Mg) in all cultivars for the Central Tablelands and for zinc in ‘Tonda Romana’ in Murray. The leaf samples in spring generally had higher macronutrient and lower micronutrient levels than leaf samples in summer, while the opposite was observed for the autumn nutrient leaf levels. N was the most removed macronutrient by the nuts followed by K, while for the micronutrients, Fe had the highest amounts present in the nuts and Mn came second. The removal of nutrients by the nut crop needs to be considered for fertiliser application together with the leaf nutrient levels.