PT - JOURNAL ARTICLE AU - Werner, L.P. AU - Jull, L.G. TI - Fertilizer Nitrogen Uptake and Partitioning in Young and Mature Common Hackberry (<em>Celtis occidentalis</em>) Trees AID - 10.48044/jauf.2013.012 DP - 2013 Mar 01 TA - Arboriculture &amp; Urban Forestry (AUF) PG - 85--93 VI - 39 IP - 2 4099 - http://auf.isa-arbor.com/content/39/2/85.short 4100 - http://auf.isa-arbor.com/content/39/2/85.full AB - Twenty-one mature and thirty-six young common hackberry (Celtis occidentalis L.) trees received a single application of 15N double isotope enriched ammonium-nitrate (NH4NO3) fertilizer. Application rates were 0, 0.49, and 1.47 kg N 100 m−2 of canopy coverage, respectively. Foliage, current season stem wood, stem wood, root, and fruit tissues were analyzed for total concentration [N] and nitrogen derived from fertilizer (NDFF). Growth phase and application rate did not consistently affect total % [N], particularly the N demanding foliage. Growth phase and application rate significantly affected the percentage of NDFF. In every instance, NDFF was highest in the tissues of young trees and/or trees receiving the 1.47 kg N 100 m−2 application rate. Mature trees relied upon previously assimilated N to meet the annual demand for N to a greater extent than young trees.