Effect of traditional and slow-release N fertilizers on growth of olive nursery plants and N losses by leaching

Abstract

‘Picual’ olive trees ( Olea europaea L.) growing in 3 l plastic pots were fertilized with traditional or slow-release N fertilizers to study their growth and to determine N leaching losses. The traditional N fertilizers used were urea, ammonium sulfate, ammonium nitrate, and calcium nitrate; the slow-release N fertilizers selected were a sulfur-coated urea (Greenmaster), a nitrification inhibitor (Basammon), a low solubility material (Floranid), and a resin-coated urea (Multicote). Each plant received 2 g N from one of the aforementioned N fertilizers at the beginning of a first experiment, and 0.75 g N in a second experiment. Fertilized plants showed significantly increased vegetative growth compared to controls, but plants fertilized with 0.75 g N exhibited a greater shoot growth than those that received 2 g N. No significant differences were found among fertilizers when 0.75 g N was applied, but greater growth was obtained with Floranid and Multicote when 2 g N was applied to each plant. Regardless of N formulation, N was accumulated mainly in leaves of the olive plants. Most of the N recovered in the leachates was in the nitrate form. Total N losses were higher when ammonium nitrate and calcium nitrate were applied, and lower with the slow-release fertilizers, except for Basammon.