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Abstract
Litter layer nitrogen flux in Lower Coastal Plain and nutrient pools of above ground tree components on Lower Coastal Plain and Piedmont were measured for Pinus taeda L. stands of three ages that received complete interspecific competition control and annual fertilization. Nitrogen fertilization increased foliar N concentration with the upper canopy having the highest concentration and this effect increased with stand age. Previously established critical concentrations for NPK did not correspond with the growth response to treatments. Fertilized treatments retained less litter layer nitrogen than the unfertilized treatments. Fertilization increased throughfall organic N and increased the litter layer retention of organic N. The amount of inorganic nitrogen in the litter leachate was low but a return of an additional 100 kg N ha-1 yr-1 with fertilization to the mineral soil over 20 years could have a large impact on available N. Approximately 60% of fertilized N could be accounted in above ground biomass.