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Spatial and depth variation of soil physico-chemical properties of two land use systems in Umudike, Abia State, Nigeria
Abstract
The effects of two land use systems, oil palm plantation and arable cropping (maize, melon and cassava mixtures) on soil physicochemical properties were evaluated along the axis of horizontal spacing and depth variability in Umudike, Abia State. Soil samples were collected at three depths; 0-20, 20-40 and 40-60cm respectively using soil auger, from five locations 10m apart within a hectare area. The samples were collected in three replicate each from the two different land uses and an adjacent area of land was sampled and used as control. The samples were analyzed in the laboratory using standard procedures. The data obtained were subjected to analysis of variance (ANOVA) and means were separated using fisher‘s least significant difference at five percent probability level. The study showed that the different land uses produced differences in soil physical and chemical properties across the fields and the values for these properties decreased with depth of the soil. However, the texture of the soil (sandy loam) was the same in both land use studied. Soil properties investigated such as organic carbon content of the arable cropped land varied, with OC value for the arable land classed as medium (1.54-1.70) compared to that of oil palm plantation which was high (2.01-2.06). The soil pH of arable cropped farmland varied from strongly acidic to moderately acidic (4.70-5.21) while oil palm farm was moderately acidic (5.13-5.33). The effect of depth of sampling indicated that soil chemical properties varied with depth indicating that beyond 40cm depth nutrient elements decreased as you move down the profile limiting plant nutrient absorption and proper crop growth and yield. Therefor spatial and depth variability in soils should be taken into consideration during soil testing to enable efficient prediction of the quantity of input (fertilizer or organic manure) required for uniform and maximum plant growth and yield.
Keywords: Land use, spatial variability, arable land, organic carbon and depth variability