Spatial Distribution of Soil Physical and Chemical Characteristics at Umaisha, Nassarawa State of Nigeria
Garba Omar and Adam Umar Adam
Keywords: Spatial Distribution, Physical, Chemical, soil Characteristics, Derived Savanna, Nigeria.
Soil samples were taken from Umaisha village (derived savanna) in Nassarawa State to produce spatial maps of soil physico-chemical properties. Surface (0 – 20 cm) composite soil samples were taken at random. The soil samples were analysed using standard methods. Data generated were subjected to descriptive statistics. Ordinary Kriging was used for extrapolation to produce the spatial distribution maps. Results indicated that the soil was characterized by a loamy sand texture with a high sand content (76.50 %) predominant over the silt (14.00 %) and clay (9.50 %) fractions. The soil showed a slightly acid reaction (mean=6.27 in H2O) and was non-saline (mean EC=0.04 Cmol/kg) and non-sodic (mean Na=0.09 Cmol/kg). Mean total nitrogen (0.67 %), calcium (3.67 Cmol/kg) and magnesium (1.04 Cmol/kg) were high while mean available phosphorus (9.84 mg/kg) and potassium (0.43 Cmol/kg) were moderate. Organic carbon (0.78 %), sodium (0.09 Cmol/kg), cation exchange capacity (5.67 Cmol/kg), exchangeable acidity (0.50 Cmol/kg) and electrical conductivity (0.04 Cmol/kg) were low in the soil. Strong variability existed in the distribution of total nitrogen (CV=134.79 %) and exchangeable acidity (CV=102.63 %). In conclusion, the soil showed moderate variability in silt (CV=69.31 %), clay (CV= 55.87 %), organic carbon (CV=47.87 %), available phosphorus (CV=55.23 %), calcium (CV=72.28 %), magnesium (CV=66.46 %), potassium (CV=65.96 %), sodium (CV=50.93 %), cation exchange capacity (CV=57.91 %) and electrical conductivity (CV=68.51 %) with only the sand (CV=17.78 %) fraction showing a low variability.