Comparatives Effectiveness of Two Vetiveria Grasses Species Chrysopogon zizanioides and Chrysopogon nigritana for the Remediation of Soils Contaminated with Heavy Metals

The study was carried out at the screen house of the Institute of Agricultural Research and Training (I.A.R&T) to determine the responses of two vetiver grasses cultivars (Vetiver zizanioides and Vetiver nigritana) on four different contaminated soils and their potential to remediate metal contaminated soil. The experiment was a 3 x 4 factorial experiment arrange in a randomized complete block design and replicated thrice. There were three levels of vetiveria grasses (V. zizanioides, V. nigritana, and no vetiver) and four contaminated soils. The absorption of metal contaminants like lead, cadmium, and zinc by the two vetiver cultivars was determined in all treatments. In mechanic village soil, V. zizanioides absorbed more of zinc followed by V. nigritana with percentage reduction of 7.0 and 5.9 respectively. In industrial waste soil, the percentage reduction of heavy metal in the soil was 27.6 and 18.8 by V. zizanioides and V. nigritana, respectively. Also in urban waste soil, there was a percentage reduction of 13.7 and 6.1 by V. nigritana and V. zizanioides, respectively. In mechanic village soil, V. nigritana absorbed more of cadmium in the soil than V. zizanioides with percentage reduction of cadmium being 30.5 and 26.2 respectively. In urban waste soil, there were percentage reductions of 7.1 and 6.8 in V. nigritana and V. zizanioides. In mechanic village soil, V. nigritana absorbed more of lead than V. zizanioides with percentage reduction of 36.3 and 43.4 respectively. In urban waste soil, there were percentage reduction of 10.2 and 6.3 by V. zizanioides and V. nigritana respectively. In industrial waste soil, there were percentage reduction of 39.2 and 29.9 by V. zizanioides and V. nigritana respectively. Vetiver nigritana, the local variety, proved to have the great potential of phytoextracting the heavy metals in the contaminated soils than the exotic cultivar (V. zizanioides).