Effects of Nitrogen, Phosphorus, and Lime on the Forest Floor and Growth of Pole‐size Loblolly Pine

Abstract Changes in the nutrient content of the forest floor and tree growth were studied after application of N P, and lime to a pole‐size loblolly pine (Pinus taeda L.) plantation in the South Carolina Piedmont. Nutrients move with varying speeds through the forest floor. Nitrogen broadcast at a rate of 56 kg/ha could not be detected in the forest floor after 10 months, but relatively large percentages of applied P, Ca, and Mg were retained for longer periods. Supplementing N with lime reduced the quantity of N in the F layer, probably because of higher nitrification and volatilization rates. The L layer of the forest floor, consisting of needles that fell after fertilizers and lime were applied, more readily reflected application of P, Ca, and Mg than did intact foliage. Dominant and codominant trees responded in the second growing season to treatments containing N. The duration of the response to the relatively light rate of N lasted from 1 to 3 years. Applying lime with N produced a positive response that was still evident after the fifth growing season. Applied P had no significant effect on growth.