Effect of Palm Oil Milling Wastes on the Physico-Chemical Properties of Soils in Okija, Southeastern Nigeria
This research work was carried out to determine the physico-chemical properties of soils as affected by palm oil milling wastes in Okija, Anambra state, Nigeria. Soil samples from an abandoned palm oil mill (site 1), active palm oil mill (site 2) and a fallow land (site 3) were collected from three mini-pits per land unit at 0-20 and 20-40 cm depths. The soil samples were air-dried, sieved with a 2-mm sieve and analyzed for physico-chemical properties. Data collected in a Randomized Complete Block Design (RCBD) were subjected to analysis of variance. ECEC were significantly different (p<0.05) in the surface and subsurface soils among the sites. Significant differences also existed among bulk density of the surface soils. Again, significant difference existed in the Ca2+ content of the surface and subsurface soils among the sites. The Ca2+ content of the soils of abandoned palm oil mill (13.98 Cmolkg-1) was about 50% more than that of soils of the other two study sites. Available phosphorous in the study sites was highly variable (CV = 71 %) and the values were significantly different in the surface and subsurface soils among the sites. There were significant differences in the organic matter contents among the surface soils of the study sites and were highly variable (CV= 53%). It is therefore advisable that palm oil mill wastes especially palm oil mill effluent undergoes some form of treatment or decomposition before deposition on the soil.
Keywords: Palm oil milling effluent, soil properties, fertility indices, target soil survey, mini-pits.