Abstract

The assessment of degradation status of wetland soils under five different land use types (LUTs) in Ogun state, Nigeria were studied. The laboratory study was conducted to determine the physical, chemical and biological properties of these wetlands and the results obtained were compared with the food and agriculture organization (FAO) standard indicators and criteria for land degradation assessment. The textural composition of the soil ranged from sandy loam to sandy clay loam. Total porosity was generally low with the mean value of 40.5%. The pH ranged from moderately acidic to slightly alkaline with fallow soil having the highest value. Available phosphorus was low across the LUTs. Total nitrogen was predominantly low in most of the cultivated soils to moderate in the fallow soils. Cation exchange capacity (CEC) was low, while the exchangeable sodium percentage (ESP) was high (>5) in all the LUTs. The organic matter ranged from low to moderate indicating low nutrients status of the soil. The soils were classified and placed in the order Alfisols. The degradation results showed that most of the cultivated wetlands were highly degraded compared to the reference (fallow) soils which were slightly degraded. It is opined that soil conservation practices like the use of inorganic fertilizers, organic manure, and composts should be intensified in these fragile low fertile wetlands. Also, there should be a periodic monitoring of the fertility status of the wetlands from the time it is first open for cultivation to subsequent uses.

Key words: Conservation, deforestation, environment, soil management, vegetation.