Fertilizer Fate in a 13-year-old Slash Pine Plantation1
- Eugene Shoulders and
- Allan E. Tiarks2
Surface application of 403 kg N, 95 kg P, and 64 kg K per ha to a 13-year-old slash pine (Pinus elliottii Englem. var. elliottii) plantation on Caddo loam soil increased total volume growth during the next 6 years by 8.3 m3/(ha·year). Trees responded rapidly to the fertilizer; measurable differences in diameter growth developed by mid-May. Fertilization markedly increased the amount of N, P, and K accumulated in current-year needles during the first year after treatment. Fertilized trees continued to accumulate more P in current foliage for at least 8 years. Ratios of Rb/K in foliage indicated that K from the fertilizer comprised 27% of K accumulated in current-year needles of fertilized trees during the fifth and sixth growing seasons, and 20% accumulated in the eigth. Ten months after treatment, added K had apparently disappeared from the top 13 cm of soil, but about half the added P remained available there. After 8 years, fertilized soil contained 40 ppm available P in the 0.9 cm layer; unfertilized soil contained only 2 ppm. In 8 years, fertilized plots accumulated 9.2 metric tons/ha more litter than did control plots. Litter had 50 kg/ha more N, 11.3 kg/ha more P, and 5.1 kg/ha more K than did litter on unfertilized plots. Disking to incorporate the fertilizer into the soil gave no advantage.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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