Aboveground biomass production and nitrogen content in gliricidia sepium (JACQ.) WALP. under several pruning regimes

Résumé 0

"The aboveground dry matter (ADM) production and nitrogenaccumulation in Gliricidia sepium (Jacq.) Walp. under severalpruning regimes was studied to evaluate the potential for organicmatter production and total nitrogen incorporation into thesoil. The study was carried out in a 6-months-old plantation(6670 plants/ha) established under a 4×2 factorial design in asplit-plot design with four replications. The pruning frequency (4,8, 12 and 24 weeks) was assigned to main plots, whereas thepruning height (0.5 and 1.0m) was assigned to subplots. Pruningheight did not affect ADM production or its quality; however, allvariables were significantly modified by the pruning frequency.ADM increased from 0.50 up to 10.52ton·ha-1 in the 4- and the24-weeks regime, respectively. The proportion of stem biomassincreased from 20 up to 53% in the 4- and the 24-weeks regime.Overall nitrogen concentration (NC) in ADM diminished from3.19 to 2.64% upon reducing the pruning frequency from 4 to 24weeks, but total nitrogen accumulated was much higher in the24-weeks regime (272kg·ha-1) than in the other pruning frequencies,due to the larger biomass production. However, in soilsamples taken two months after the last pruning, no significantincrease in soil organic matter (SOM) or soil nitrogen (SN) wasobserved in any of the pruning regimes. In order to detectchanges in SOM and SN, a longer evaluation period might berequired to allow for biomass decomposition."