Evaluation of Vetiver Grass Buffer Strips and Organomineral Fertilization for the Improvement of Soil Physical Properties

Abstract

Soil erosion still remains the major cause of deterioration of soil physical qualities on cultivated lands worldwide. A study was carried out on erosion plots at the Teaching and Research Farm of the University of Ibadan, Nigeria to assess soil physical properties after five years of using vetiver grass buffer strips (VGBS) and organomineral fertilizer (OMF) with bare soil on which farmers had planted without soil conservation measures as the control. Samples were analyzed for water stable aggregates (WSA), mean weight diameter (MWD), bulk density, porosity and particle size distribution. The cone index (CI) was also assessed. Infiltration values were fitted to Philip’s and Kostiakov’s models. Results showed that the amount of WSA for the VGBS and OMF plots was the same (64%) and on the bare soil was 54%. The MWD on the VGBS plot was 6.11% higher than on the OMF plot and 19% higher than on bare soil. The bulk density for the bare soil was 4% higher than that of the VGBS plot. Porosity values for the VGBS and OMF plots were the same, being 8% higher than the bare soil plot. The CI was 15.7% and 7% lower on the VGBS and OMF plots, respectively, compared to the bare soil. Cumulative and initial one-minute infiltration increased by 39.4% and 35%, respectively, on the VGBS plot when compared with the bare soil. Hydraulic conductivity increased by 41.7% on the VGBS plot when compared with bare soil. The initial capacity of the soil to accept water increased on the VGBS plot by 19% over the OMF plot and 39% over the bare soil plot. The index of soil sorptivity (reflecting rate of decline of infiltration capacity) was the same for the VGBS and OMF plots and 21.78% higher than for the bare soil plot. The use of vetiver grass buffer strips on erosion-prone cultivated fields over the years could act as a source of organic fertilizer, improving soil physical properties.