DRIS-based fertilization efficiency of young hybrid poplar plantations in the boreal region of Canada

Abstract

In order to maximize early growth and establishment of planted hybrid poplars in the boreal region of Eastern Canada, growth response of four clones to fertilization was tested in two plantations. The first two fertilization treatments were based on Diagnosis and Recommendation Integrated System (DRIS), a method based on nutrient ratios: DRIS I was based on previously established norms from a study that had been conducted in the same area, and DRIS II was based on DRIS norms developed from hybrid poplars in northern Ontario, Canada. Nutrient status and growth of trees under these 2 treatments were compared to unfertilized trees and to trees under standard (STD) fertilization treatment (40 N–20P–20 K). Leaf nutrient concentrations and DRIS indices showed that fertilization treatments, and especially DRIS I corrected N deficiencies but failed to correct P deficiencies. Fertilization increased volume relative growth rate by 7.51, 4.76 and 13.25 % on average at the agricultural site for DRIS I, DRIS II and STD treatments respectively, compared to no fertilizer application. At the forest site, fertilization treatments based on DRIS indices (DRIS I and DRIS II) increased growth rates (6.67 %) slightly more than the standard treatment (5.80 %). Overall, although DRIS-based fertilization treatments generally increased growth rates, they were often equal to or less efficient than the STD treatment, and may not be as practical as using a standard fertilization recipe.