Comparative Effects of Vetiver Grass (Chrysopogon zizanioides) Strips, Vetiver Mulch and Veticompost on Soil Quality and Erodibility of a Sloping Land

This study investigates the influence of vetiver grass strips (VGS), vetiver mulch (VGM) and composted vetiver prunes (veticompost) on soil quality of an eroded land in the Institute of Agricultural Research and Training, Ibadan (70 22’ N; 30 50’E), Nigeria. The treatments were 3-m wide VGS established at 10-m inter-row spacing, VGM imposed at 5 Mg ha-1, veticompost applied at 5 Mg ha-1 and a control (no-vetiver grass). All quality indicators including physical, chemical and biological indices and soil erodibility (K) factors were determined between 2008 and 2011. Results show that soil organic matter (SOM) and associated nutrients play a major role in soil quality variation. VGM had the highest impact on soil quality (76.5%) but not significantly different (P<0.05) from veticompost (72.5%). Soil quality ratings were in the order of VGM > veticompost > VGS > control. Significant and positive relationship (r = 0.92*) exist between soil quality ratings and maize yield, with 70% of grain yield variability accounted to the soil quality. K factor ranged from 0.013 to 0.030 Mg h MJ-1 mm-1 with the VGM and control plots having the least and highest K factors, respectively. Although the soil quality under veticompost is lower than vetiver mulch but the SOM and associated nutrients under veticompost enhanced better soil productivity, and thus accounted for higher crop yields than other treatments.