Nitrogen release from decomposing litter of Leucaena leucocephala in the dry tropics

Abstract

Experiments were made on a 2-yr old Leucaena leucocephala stand to measure the litterfall and decomposition rates. Annual litterfall was 10 t ha −1 and was maximal in the dry summer months (≈50% of total litterfall). The seasonal peaks were in June and December (15 and 11% of total litterfall, respectively). Leaves comprised 88% of the total litterfall. Litter decomposition in the field was examined using leaf, twig and fruit fractions of above-ground litter. Roots were also studied for loss of mass and N release below-ground. Loss of mass was in the order fruit > root > twig > leaf. The inital mass loss was high and there was rapid loss in the rainy season (July-September). Annual above-ground litter N content was high (256 kg ha −1) with an annual release of 208 kg ha −1 i.e. 81% of the total litterfall. N release from litter per unit area was leaves (13.2gm −2), fruits (10.5 gm −2), twigs (4.4g m −2) and roots (3.4g m −2). Litter decomposition and N release from the decomposing litter was dependent on the C-N ratio and environmental factors. N turnover time was < 1 yr for all litter fractions.