Soil fertility regeneration of impoverished ultisols of Edo State using Gliricidia sepium Jacq Walp.

Abstract

Improved fallow involving short-rotation woody and/or other perennial species are increasingly being tried as a means of sustaining crop productivity in impoverished farming systems of sub-saharian Africa. The contributions of nitrogen fixation and leaf litter of Gliricidia sepium Jacq Walp. to soil fertility regeneration of an impoverished ultisol during a two year fallow was assessed after continuous cropping for four consecutive years. One of the plots used in this investigation contained Gliricidia sepium as part of the fallow vegetation while the second plot did not. At the end of the two year fallow period, higher levels of exchangeable cations, available phosphorus and total nitrogen were recorded for the plot with gliricidia compared to the control plot. Litter from the gliricidia treated plot recorded higher nitrogen (23.5%), phosphorus (0.31%), potassium (1.3%) calcium (0.9%), lipid (10.85%) and crude fiber (4.28%) compared to control fallow plot occupied by diverse plant population, excluding gliricidia species, which recorded lower levels of nitrogen (12.31%), calcium (0.63%), potassium (1.7%), phosphorus (0.27% and lipid (9.92%) but higher crude fiber (6.18%).The incorporation of ground leaf litter into the post-fallow soil resulted in up to two fold increases in soil nutrients such as total nitrogen, available phosphorus and exchangeable cations (magnesium and calcium) in the gliricidia treated plot compared to the control plot. © 2007 Asian Network for Scientific Information.