VARIABILITY OF SOME SELECTED SOIL PARAMETERS IN A 50 YEARS INTENSIVELY CULTIVATED EXPERIMENTAL PLOT ON AN ALFISOL (IWO SERIES)

Abstract

Background. Soil has variability inherent to how its formation factors interact within the landscape. Objective. This study was carried out to describe the variability of some selected physical and chemical soil properties in a 50 years intensively cultivated field. Methodology. Eighty soil samples from a 100m × 180m plot were collected at 0 - 25 and 25 – 50cm depths and subjected to physical and chemical analysis. Semivariogram was calculated for each variable to ascertain the degree of spatial variability between neighboring observations. Results. Soil pH was moderately acidic with a mean of 5.64 and CV 6.91 % at 0- 25cm while at 25- 50cm it was strongly acidic with mean value of 5.54 and CV 7.04 %. Mean value of OC in the experimental field was higher at the top soil than sub soil with values 5.96 g/kg and 4.54 g/kg respectively with CV 38.26% and 50.44%. At 0 – 25cm, % silt had a significant negative correlation with % sand (-0.790) at 0.01%. % clay and % silt was negatively correlated (-0.428), however CEC was positively correlated with % clay (0.460) at 0.01% probability while OC concentration was positively correlated with TN (r = 0.833) at 0.01.  Semivariograms indicated the existence of moderate to strong spatial dependence of soil variables at both depths. Implications. The study was used in determining the degradation status of the soils in the area, the findings of this study also showed that spatial structure exist in the soil properties at the field scale in the study site. Conclusion. These results support the importance of collecting information in experimental fields to know how a site –specific system should be undertaken.