Abstract:
The land at Anuka, Nsukka Local Government Area of Enugu State in Southeastern Nigeria, under the sub-humid tropical climate was evaluated for maize (Zea mays), cassava (Manihot esculenta), yam (Dioscorea spp.) and oil palm (Elaeis guineensis) cultivation. Data were obtained by field study and laboratory analyses. Six pedons were dug and described: two pedons each for maize and oil palm fields, and one each for yam and cassava fields. These pedons were dug to represent sampling units. Auger samples were also purposefully collected from the sampling units at depths 0 - 20cm and 20 - 40cm. This was to investigate the nutrient spread in the area. Soil samples from the pedogenetic horizons of the pedons were collected after profile description, processed and analyzed. The pedons were designated P01 = cassava field, P02 and P03 = maize fields, P04 = yam field, and P05 and P06 = oil palm fields. The textural classes of the soils included sandy clay loam, sandy loam, sandy clay, loam, clay loam and clay, but the dominant textural class is sandy clay loam. The overall results showed that the soils are acidic; the phosphorus content is generally low; organic matter ranged from 0.42 - 4.31 %, decreasing down the profile depth and is medium (>2.0 %) for epipedons. Exchangeable bases are generally low: low exchangeable Ca (<3.2 cmol kg-1), low to medium exchangeable Mg (0.2 - 3.2 cmol kg-1), very low exchangeable Na (<0.70 cmol kg-1) and deficient exchangeable K (<2.0 cmol kg-1). Total nitrogen content is moderately low to very low (0.042 % < N < 0.196 %). The soils met the criteria for classification as Typic Dystrustults (P01, P03, P04, P05 and P06) and Aquic Argiustults (P02) (Soil Taxonomy), correlated to Acrisols (FAO/UNESCO). The results showed that although climate and topography are optimum or near optimum, there was no current highly suitable (S1) soil unit for maize, cassava and yam cultivation by both parametric and non-parametric methods of suitability evaluation. However, soil units P01 and P02 showed actual and potential S1 for oil palm production in the study area. None of the sampling units showed high suitability for its current utilization type. The severe constraints to crop cultivation in the area are generally low fertility for all soil units; wetness for soil unit P02 and adverse soil physical characteristic for soil unit P04. Application of organic manure, use of balanced fertilizer and drainage management practices are necessary for maximum productivity of Anuka soils for the evaluated crops.
