ABSTRACT

The Coastal Plain Sands of Abia State spans from Umuahia North to Ugwunagbo Local Government Area, hence it was studied adopting the free soil survey approach. Data were obtained from the field and laboratory analyses. Three Mapping units were delineated and six pedons were sunk as designated; COPED I (Pedon 1 and Pedon 2), COPED II (Pedon 4 and Pedon 5) and COPED III (Pedon 3 and Pedon 6). Physicochemical characterization of the pedons was studied to classify the soils and determine the best possible land use and management of the soils. Following the USDA Soil Taxonomy, the pedons were classified as Rhodic Paleudult (Pedon 1), Grossarenic Paleudult (Pedon 3) Typic Paleudult (Pedon 2, 4. 5, and 6) and they all correlated with Haplic Acrisol in (WRB). The soils were generally deep (> 100 cm) with soil textures dominated by sandy loam and loamy sand at the soil surface, and sandy clay loam at the sub surface. Generally the soils were acidic with pH ranges of (4.8 - 5.5) in CODEP I, (4.0 - 5.1) in CODEP II, (4.0 - 4.8) in CODEP III. Effective Cation Exchange Capacity were observed to be low with ranges of (5.37 - 7.70 cmol/kg) in CODEP I, (0.49 - 6.39 cmol/kg) in CODEP II, (2.92 - 5.64 cmol/kg) in CODEP III. Base saturation were found to be low to moderate with ranges of (29.0 - 42.2 %) in CODEP I, (23.8 - 59.7 %) in CODEP II, (29.0 - 57.4 %) in CODEP III. Bulk Density showed ranges from (1200 - 1720 kg/m3) in CODEP I, (1320 - 1760 kg/m3) in CODEP II, (1210 - 1750 kg/m3) in CODEP III. Saturated Hydraulic Conductivity ranged was (1.57 - 87.2 cm/hr) in CODEP I, (22.3 - 121 cm/hr) in CODEP II, (1210 - 1750 cm/hr) in CODEP III. The pedons were evaluated for mung bean production and suitability using the Riquier’s productivity index and Khiddir Index of Productivity approach. From the two suitability classification methods, based on mapping units, the suitability classification method of Riquier’s productivity index revealed that; COPED 1 and COPED II were currently, marginally suitable S3 and potentially, moderately suitable S2, COPED III were currently, not suitable N and potentially, marginally suitable S3. While the suitability classification method of Khiddir Index productivity revealed that COPED 1, COPED II, COPED III were currently, not suitable N and potentially, marginally suitable S3. From comparisons, it was concluded that the obtained indices by the Riquier index presented higher and better land suitability ratings more than the Khiddir method. Correlation analysis exposed a positive correlation between the two methods. Fertility Capability Classification (FCC) of the three mapping units (COPED I, COPED II and COPED III) were classified as ‘SLkmh’ with potassium deficiency (k), low organic carbon saturation (m) and acidity (h) as the estimated limitations. Principal Component Analysis reduced the factors and processed the highly correlated pedogenic variables; the soil organic matter, sand texture, moisture contents, pH and nutrient contents were revealed as the principal limiting factors in this study.