Decomposition and nitrogen release patterns of Paraserianthes falcataria tree residues under controlled incubation

The residue quality of Paraserianthes falcataria leaves and roots was determined separately and as a mixture, and residue decomposition and nitrogen release were assessed using the super(15)N dilution technique. The study was carried out using an Ultisol. The quality indices of leaves alone were found to be about three times smaller than those of roots alone, but the indices of the mixture were approximately two times smaller than those of roots alone. Root residues alone produced the least amount of carbon dioxide, followed by the mixture and the leaves alone, and the cumulative CO sub(2) evolution of the residues followed the same sequence as that for N mineralization. The percentage of ammonium N cumulatively derived was lowest for roots alone, followed by the mixture and leaves alone. After incubation for about 20 d, P. falcataria leaves and the mixture caused a significant decrease in soil pH.