PROFILE ANALYSIS OF SOIL PHYSICAL PROPERTIES ON VERTIVER AND NON VERTIVER GRASS SOIL (CASE STUDY AWKA AGRICULTURAL ZONE OF ANAMBRA STATE, NIGERIA)

ABSTRACT Field study was carried out to assess the Profile analysis of soil physical properties on a vetiver and non-vetiver grass soils located at Nnamdi Azikiwe University Awka, Anambra state, Nigeria. Soil samples were collected from the profile pit of both vetiver grass soil (VR) and adjacent non-vetiver grass soil (NVR) of the site. Disturbed and undisturbed soil samples were collected randomly at three depths (0-15cm, 15-30cm and 30-45cm) in three replicates to assess the soil physical properties. Following standard procedures, the soil samples collected were analyzed in the laboratory for selected soil physical and hydraulic properties. The parameter measured were, soil bulk density (BD), saturated hydraulic conductivity (Ksat), total porosity (Ft), permanent wilting point (PWP), field capacity (FC), moisture content (M.C), available water capacity (AWC) and particle size distribution. Data collected were subjected to analysis of variance (ANOVA) using GenStat statistical package where means were separated using Fisher’s least significant difference (FLSD) at 5%. Results of the particle size distribution showed that the soil is predominantly loamy sand which was significant (p≤0.05) as influenced by the grass cover across the depths. The surface soil (0-15cm) had the highest percent sand on NVR (94.00%) and VR (89.00%), followed by the subsoil, while the least values were obtained on NVR at depth 30-45cm. Bulk density shows no significant difference when comparing VR and NVR. NVR had higher BD of 1.54g/cm3, relative to VR whose value was 1.49g/cm3. Porosity had no significant difference with respect to the effects of the grass cover, but significant across the depths. VR had higher porosity (43.84%) than NVR whose value was 41.76%. The moisture content showed that there was no significant influence of vetiver on the main effect as compared to the adjacent grass cover. Though, VR had higher M.C as to compare the adjacent grass cover with a value of (5.01%) while the NVR had the value of 4.8%. Conversely, the effects showed that there was a significant increase down the profile with depth 30-45cm having the highest value of 5.20% followed by 15-30cm which has the value of 5.14% and the least was observed at the top soil (0-15cm) with a least value of 4.40% in that order. The saturated hydraulic conductivity (Ksat) was not significant on the main effect, but significant on the depth down the profile. The NVR tends to have higher Ksat of 12.13cm/hr while the VR has the value of 11.58 cm/hr. Field capacity also had no significant difference on the main effect with VR having higher value of 10.24 % as relative to NVR which had the lower value of 9.74%. With respect to depth, there was a significant increase down the profile with depth (30-45cm) having the highest value of 10.24%, followed by depth 15-30cm which had the value of 9.95% and the least was observed at depth 0-15cm with a value of 8.28% respectively. The permanent wilting point showed that there was no significant difference on the main effect with VR having higher value of 4.43 % as compared to NVR which had the lower value of 4.42% respectively. The depth showed a significant increase down the profile. In the same manner, the AWC showed no significance on the main effect, but was on across the depth down the profile. The interaction effect between the grass cover and depths showed a high level of significance in all the physical and hydraulic parameters as measured. Hence, it was recommended that planting of vetiver grass and other related grasses helped to significantly influence the physical properties and moisture characteristics of the soil and to avert the risk of erosion because of the erosive nature of the soil.