Response of Mature Olive Trees with Adequate Leaf Nutrient Status to Additional Nitrogen, Phosphorus, and Potassium Fertilization

The aim of this study was to evaluate the effect of applying additional nitrogen (N), phosphorus (P) and potassium (K) to trees with adequate leaf nutrient status. Growth and yield of mature 'Picual' (208 plants/ha) and 'Arbequina' (1667 plants/ha) trees were determined in 2007 and 2008. N was applied to the soil in spring as ammonium sulfate at a rate of 92 and 138 kg N/ha in 'Picual', and 250 and 367 kg N/ha in 'Arbequina' in 2007 and 2008, respectively. P and K were applied by foliar fertilization during the summer. P was applied at a rate of 1.3 and 1.5 kg P2O5/ha in 'Picual', and 6.5 kg P2O5/ha in 'Arbequina' in 2007 and 2008, respectively. K was applied at 3.1 and 7.2 kg K2O/ha in 'Picual', and 8.3 and 25.3 kg K2O/ha in 'Arbequina' in 2007 and 2008, respectively. Trunk perimeter only increased in 'Picual' with N fertilization. In 2008, yield increased in N-, P- and K-fertilized 'Arbequina' but not 'Picual' trees. Although olive trees initially had adequate leaf nutrient levels, these preliminary results show positive responses to additional N, P and K fertilization.