Initial availability of NO3, NH4, and urea applied to limed or unlimed pine bark as well as the form of N available over a period of 21 days was determined. Nitrate was not present in significant amounts when N was supplied as either urea or NH4, and the extractable amounts of both urea and NH4 declined significantly over the course of the experiment. Urea was the least effective of the N forms in supplying N in an extractable form. With NO3 as the N source, addition of lime to pine bark resulted in significant reductions in extractable NO3. Applications of NH4 gave relatively equal amounts of extractable N as NH4 from limed and unlimed pine bark after 21 days. It was concluded that N interaction and N transformations with these N forms in pine bark would influence total available N as well as the form of N available for plant growth.
Received for publication 24 Sept. 1984. A contribution of the Univ. of Georgia Agricultural Experiment Stations, College Station, Athens. This work was supported by Hatch Act 775. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.