Effect of Nitrogen and Phosphorus Fertilization on Growth in a Sweetgum Plantation in Southeastern Arkansas

Effects of nitrogen and phosphorus fertilization (nitrogen only, phosphorus only, nitrogen + phosphorus, and no fertilizer) on the growth of a sweetgum (Liquidambar styraciflua L.) plantation were tested in a poorly drained Henry silt loam soil in southeastern Arkansas. The plantation was fertilized when 4 yr old. Nitrogen fertilization increased height, dbh, and stem volume growth 1 yr after the application, and the mean height, dbh, and stem volume were significantly greater for the trees with nitrogen fertilization than for the trees without nitrogen fertilization through 10 yr. Phosphorus alone did not affect tree growth. However, height growth was improved by the combination of nitrogen and phosphorus eight yr after fertilization. Nitrogen also increased crown width and length through the first 4 yr, but crown width and length were similar among treatments after crown closure occurred by 13 yr. South. J. Appl. For. 22(3):163-168.