IMPACT OF CONTINUOUS FARMING ON THE MICROBIAL AND PHYSIO-CHEMICAL CONSTITUENTS IN GROUNDWATER

Water is one of nature’s most important gift all living things. The importance of this gift of nature is such that without it man could hardly exist. However, the major source of water is groundwater which agricultural activities contaminate through infiltration of organic and inorganic substances used on the farm. The aim of the study is to investigate the effect of agriculture on groundwater quality. Groundwater samples were collected from thirteen (13) wells in Oyo State Agricultural Development Farm (OYSADEP) in Ogbomoso South Local Government, Nigeria. The samples were taken to the laboratory for Physical, Chemical and Bacteriological analysis. The parameters determined include pH, temperature, BOD,COD, Iron (Fe2+), Sulphate (SO4 2+),Potassium, Phosphorous (PO4 3- ) and heavy metals like Lead (Pb2+), Copper (Cu2+) and Zinc (Zn2+). Pb2+, Cu2+ and Zn2+ concentrations in the samples indicated groundwater pollution but were below the WHO limits for consumption and USEPA Maximum Contaminant Level. The pH ranges from 5.57 to 6.65 indicating toxic pollution. In the same vein, Sulphate and Ammonia-Nitrogen concentrations ranges from 6.17mg/L to 37.23 mg/L, 1.03 mg/L to 6.96 mg/L respectively, only sample 1 contain 0.05mg/L of copper, no data for Zinc. Total Coliform Count ranges from 1.2x103 cfu/ml in Sample 4 to 17.2x103 cfu/ml in Sample 13 exceeding WHO standards. Moreover, Total Viable Count, Total Fungal Count and Total Coliform Count was high. Statistical analyses using nonparametric Spearmen correlation indicated significant differences at 0.05. A positive moderate relationship exists between Potassium and Iron. A very strong correlation exists between potassium and Electrical Conductivity, TFC and TVC also show strong correlation. It is concluded that the samples were polluted due to agricultural activities on the studied farms; the bacteriological constituents of the entire samples were high due to organic manure and require treatment before domestic use. Water treatment, groundwater monitoring and effective nutrient management in the study is recommended.