Evaluation of the Quality of Soils Retained by Vetiver Grass Hedgerows on Runoff Plots in Southwest Nigeria
*1Oshunsanya, S.O., 2J.A. Fagbenro and 3N.O. Anenyeonwu
1&3Department of Agronomy, University of Ibadan, Nigeria
2Department of Crop Production, Soil and Environmental Management, Bowen University, Iwo, Nigeria
*Corresponding author: soshunsanya@yahoo.com (+234-8059759169)
Accepted on April 10, 2012
Abstract
In spite of the wide acceptability ofvetivergrass technology as soil conservation method, little or no attempt has been made in quantifying the soils retained by vetiver grass hedgerows(VGH) for sustainable agricultural production. Experiment was therefore conducted at the University of Ibadan Teaching and Research Farm to evaluate spacing effectsof VGH on slope stabilization and quality of soilsretained on runoff plot.Seven-year old vetiver grass hedgerows planted at 5m (5mVGH), 10m (10mVGH) and 20m (20mVGH) surface intervals across the slope on runoff plot and control (no-vetiver), replicated thrice in a Randomised Complete Block Design (RCBD). The plots weresampledat 1m, 3m and 5m distances away from 5m VGH, 10m VGH and 20m VGH and at the centre of control plot giving rise to ten treatments.Results showed that the heights of soils retained by seven-year old vetiver grass hedgerows spaced at 5m, 10m and 20m surface intervals across the slope were 5.7 cm, 6.0 cm and 14.8 cm, respectively.Consequently, the corresponding spacing of5m VGH, 10m VGH and20m VGH across the slope reduced the slope percent locally from 6% initially to 5.955%, 5.952% and 5.880%, respectively. Soil samples obtained from 10m VGS especially at 3m and 5m distances away from the vetiver grass hedgerows were better than other treatments in terms of soil water retention, soil structure and soil texture. However, there was no significant difference between 5m VGS and 10m VGS in terms of soil quality. The result further showed that the wider the spacing of vetiver grass hedges, the higher the soil accumulation and consequently the higher the degree of slope stabilization. In terms of soil quality, 10mVGS is better than 20m VGS and control plots with respect to soiltexture, soil structure and water retention ability of soils for sustainable crop production.