The effect of abattoir effluent on physicochemical parameters and earthworm abundance of soils around Gbagi stream (Odo-Eran), Ibadan, Nigeria.

Abstract

The discharge of untreated effluent into both soil and water bodies is known to degrade the natural environment, including soil quality. The present study investigates the effects of Gbagi abattoir effluent on the physicochemical properties of the soil and earthworm abundance around the abattoir. Top soil samples were collected at a depth of 0 – 30 cm between March 2008 and January 2010 and analysed using standard methods. Soil properties include sandy-loam soil; high organic matter content and very high electrical conductivity. The mean values of some physicochemical parameters were: pH 7.69, phosphorus, 84.81 mg/Kg, nitrate-nitrogen 635.47 mg/Kg, sulphate-sulphur 55.98 mg/Kg. Mean values of exchangeable bases are Na (1294.78 mg/Kg), K (3081.67 mg/Kg), Mg (1774.23 mg/Kg) and Ca (27826.41 mg/Kg) and the micronutrients Zn, Mn and Fe were 321.68, 420.49 and 35558.41 mg/Kg respectively; these values being much higher than the results obtained from the control site. Three species of earthworms recorded throughout the sampling period were Hyperiodrilus africanus, Eudrilus eugeniae and Dichogaster modigliani. The results show a negative and consistent decline in soil health and earthworm diversity and abundance in the sampling location as against the control. This calls for proper treatment of effluent before release into the environment.