The Effect of Broadcast Nitrogen Fertilization Rates and Placement on the Growth of Green Ash Trees

Abstract

Tree responses to slow-release nitrogen fertilization treatments were limited, but application of fertilizer to the inner half of the root zone improved caliper growth and relative chlorophyll content. Concentrating nitrogen fertilizer applications closer to the base of the tree may be able to take advantage of naturally higher root density, in addition to any further root stimulation resulting from the applied fertilizer treatment. The study site was moderately fertile, as are many urban landscapes where lawn and planting beds surrounding trees are fertilized. The pre-existing level of fertility may have contributed to the limited growth response to the nitrogen applications.