Ammonium Sorption Characteristics of Soils of Coastal Plain Sand in Owerri West Imo State

Information on the ammonium sorption capacity of soils is very crucial in the development of sound ammonium fertilization and management. This study was therefore carried out to determine the ammonium sorption characteristics of soils of coastal plain sand formation in Owerri West LGA of Imo State. Samples were collected from three locations (FUTO, Ihiagwa and Umuokanne), at three depths (0-15, 15-30, 30-45 cm), giving a total of nine observational units. The experimental design was a 3 x 1 factorial in Randomized Complete Block Design (RCBD), the parent material and soil depth was the factors under consideration. Statistical analysis did not show significant (P>0.05) variation in soil physical and chemical properties with location. However, most of the properties increased with depth. Data obtained from the analysis were statistically analyzed using Analysis of Variance (ANOVA) and means separated using Lsd(0.05). Correlations between soil routine properties and ammonium sorption parameters were done using SPSS (Version 16.0). Soil Ammonium sorption properties of the soils showed variability with location and depth. FUTO had the highest capacity to absorb ammonium (445mg/kg). For all locations, maximum adsorption capacity increased with depth. However, the affinity coefficient was greatest in soil of Ihiagwa (3.25mg/kg) and this increased with depth for all soils. The adsorption maximum and affinity coefficient correlated positively with clay and negatively with sand and organic matter. Langmuir and Freundlich isotherms were applied to test the sorption data. Comparing the fitness of the ammonium sorption models using the R2 values, it was evident that Freundlich Model better described and predicated the ammonium sorption parameters and is therefore recommended for the study of soils of these locations.