EFFECT OF FERTILIZER APPLICATIONS ON HAZELNUT LEAF AND SOIL CONCENTRATIONS

Fertilizer response trials involving potassium (K), magnesium (Mg), boron (B), copper (Cu) and zinc (Zn) were conducted in four commercial hazelnut orchards in the Fraser Valley of British Columbia. The use nutrients were selected based on information as leaf nutrient:nut correlations, comparisons of leaf nutrient concentrations to previously proposed targets in a preliminary survey of seven orchards and to published research information. No yield nor consistent nut quality effects were measured in any of the nutrient response trials, partly due to large variability in the nut measurements. Leaf analyses showed that K, Mg, Cu and Zn were not readily taken into the plant from the soil fertilizer applications. Soil analyses of these nutrients suggested that the fertilizers, particularly Cu, but also K, Mg and Zn, were not readily available to the plant due to a reaction of the nutrients in the soil. There was no apparent difference in availability between soil-applied magnesium oxide and magnesium sulfate fertilizers. Foliar application of Mg increased leaf Mg, but there was no measurable short-term effect on nut production. Soil-applied B increased leaf B in all B application trials and application of K together with B soil fertilizer reduced leaf B concentration. Foliar application of B did not significantly increase leaf B concentration when applied at the one kg B ha^-1 rate.