LOBLOLLY-PINE SEEDLING RESPONSE TO FERTILIZER AND LIME TREATMENTS ON A SPODOSOL

Loblolly pine trees (Pinus taeda L.) grow poorly on the Spodosols of the mid-Atlantic Coastal Plain. This greenhouse study was undertaken to determine the effects of N, P, S, micronutrients, and lime on the growth of Loblolly pine seedlings in the A1 horizon of a Lynn Haven fine sand (sandy, siliceous, thermic Typic Haplaquod). Nitrogen, and N-P in combination resulted in increased growth of the pine seedlings. A small application of CaCO3 (2337 kg/ha) resulted in reduced growth and increased foliage necrosis. This negative effect was overcome by N applications. Micronutrients alone had little effect on growth and the foliage concentrations were adequate with all treatments. Sulfur treatment had a slight effect on plant growth but, with S, foliage N was increased from 17.5 to 19.0 g/kg. Aluminum concentrations were determined to be at nontoxic levels in this soil horizon. We postulate that the negative effect of CaCO3 on plant growth was due to reduction of available N. The mechanism for this result has yet to be elucidated.