The characterization of spatial variability of soil physical and chemical characteristics is very important for precision farming and managing agricultural production. Therefore, the objective of this study was to evaluate the spatial variability of selected physical properties of a soil under different crops in Ado Ekiti, Nigeria using descriptive statistics and geostatistical techniques. Grids of 10 m x 10 m were set up on the field within three land uses. The field was about 3 hectares, out of which 1ha was apportioned for cowpea, 1ha was for sole maize and the rest for maize/cassava intercrop. A total of one hundred and eighty-four (184) georeferenced surface samples were collected for analysis of texture, bulk density (BD), particle density (Pd), porosity (Pt) and saturated hydraulic conductivity (Ks). The study used descriptive statistics to investigate the striking features in each soil property and further adopted semi-variogram and kriged maps to assess the spatial dependence and classification of the soil properties respectively. The soil properties showed varying degrees of spatial variability, with Ks highly variable (118%) than others. There was weak correlation between Ks versus BD (12%) and Pt (-14%) but the correlation was significant with Original Research Article

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The sustainable soil management necessary to maintain soil quality depends on the understanding of how the soil responds to agricultural practices over time. This paper reports the changes in physicochemical properties that resulted from different cropping systems on a soil in Ado Ekiti, Nigeria. Soil samples were collected from sole maize plot (1.0 ha), sole cowpea plot (1.0ha) and cassava/maize intercrop plot (0.6ha) on a land that was previously under fallow. The sand, silt and clay contents of the soil and some selected chemical parameters varied considerably within the study area (different cropping zones). The soil was generally sandy loam and was found to vary from slightly acidic to slightly alkaline and generally low in Soil Organic Matter (SOM) and Available P (Av. P) with no salinity problem. High magnitude of variability was observed for Electrical Conductivity (EC), Av. P and SOM while pH had the least magnitude. A geostatistical evaluation of the soil chemical properties showed moderate to strong spatial dependence. The geospatial maps clearly revealed the heterogeneity of the soil chemical properties across the field. Both classical statistics and geo-statistical analyses of the soil of the area provided a better understanding of the spatial variability of soil chemical properties and the influence that such could have on crop performance. The results indicated that the soil pH is slightly acidic and contained low amounts of both SOM and Av. P. It is suggested that planting of cover crops, minimum tillage and controlled application of phosphate fertilizer should be done so as to increase the SOM, improve Av. P and maintain the soil pH. Further studies should be conducted to include other soil chemical properties such that robust site specific management programme could be effected.