Resumen

MELCHOR MARROQUIN, Isidro; VARGAS HERNANDEZ, Jesús; VELAZQUEZ MARTINEZ, Alejandro  y  ETCHEVERS BARRA, Jorge. Aboveground biomass production and nitrogen content in Gliricidia sepium (Jacq.) Walp. Under several pruning regimes. INCI [online]. 2005, vol.30, n.3, pp.151-158. ISSN 0378-1844.

The aboveground dry matter (ADM) production and nitrogen accumulation in Gliricidia sepium (Jacq.) Walp. under several pruning regimes was studied to evaluate the potential for organic matter production and total nitrogen incorporation into the soil. The study was carried out in a 6-months-old plantation (6670 plants/ha) established under a 4×2 factorial design in a split-plot design with four replications. The pruning frequency (4, 8, 12 and 24 weeks) was assigned to main plots, whereas the pruning height (0.5 and 1.0m) was assigned to subplots. Pruning height did not affect ADM production or its quality; however, all variables were significantly modified by the pruning frequency. ADM increased from 0.50 up to 10.52ton·ha^-1 in the 4- and the 24-weeks regime, respectively. The proportion of stem biomass increased from 20 up to 53% in the 4- and the 24-weeks regime. Overall nitrogen concentration (NC) in ADM diminished from 3.19 to 2.64% upon reducing the pruning frequency from 4 to 24 weeks, but total nitrogen accumulated was much higher in the 24-weeks regime (272kg·ha^-1) than in the other pruning frequencies, due to the larger biomass production. However, in soil samples taken two months after the last pruning, no significant increase in soil organic matter (SOM) or soil nitrogen (SN) was observed in any of the pruning regimes. In order to detect changes in SOM and SN, a longer evaluation period might be required to allow for biomass decomposition.

Palabras clave : Pruning Frequency; Pruning Height; Biomass Distribution; Soil Organic Matter.