Chemical Composition of Foliage from Fertilized Plus Douglas Fir Trees and Adjacent Unfertilized Check Trees

Abstract

AbstractShoots of the 1960, 1961, and 1962 growth were removed from two fertilized plus trees and two unfertilized adjacent check trees in April 1963. Each plus tree received 80 pounds of 16‐20‐0 ammonium phosphate sulphate fertilizer in April 1961, and 40 pounds of the same fertilizer in April 1962. The length of the shoots was measured and needle production was determined. Needles from each of the 3 years of growth were analyzed for N, P, K, Ca, Mg and S.Fertilization increased the length of the 1962 shoots. Diameter of the shoots also appeared to be increased. Needles from the fertilized trees seemed to be larger and darker green in color. Weight of needles produced in 1962 was greatly increased by fertilization. Concentration and weight of N in needles was markedly increased by fertilization, particularly in the 1962 growth. Phosphorus concentration was slightly reduced by fertilization. However, the weight of P in the 1962 needles was increased by fertilization. The N/P ratios in all needle samples from the fertilized trees were much greater than those in the unfertilized check trees. Although K concentration was reduced in the foliage from fertilized trees, weight of K was not influenced by fertilization. Potassium percentage tended to be lowest in the oldest tissue, and highest in the youngest tissue of all trees. Concentration and weight of Ca was highest in foliage from the fertilized trees. Calcium concentration increased with age of all foliage samples. Fertilization resulted in an increase in concentration and weight of Mg. Concentration and weight of S was highest in the foliage from fertilized trees. Older needles appeared to have a higher S concentration than the younger needles.