Evaluation of Some Metals Content and Physicochemical Properties of Some Major Rivers as Sources of Irrigation Water in Mid-Benue Trough

摘要

Irrigation Water were sampled from some major rivers in the mid-section of Benue Trough for twoconsecutive years, 2011 and 2012 and analysed for some metals contents and physicochemical properties. The resultsshowed that irrigation water were slightly (pH 6.5) to moderately (pH 5.5) acidic and good for irrigation withminimal or no liming. Very low pH delays nutrients uptake by plants and therefore plant metabolism. Levels of totalsoluble salts, Mg2+, Ca2+, Na+ and K-were within the acceptable limits for irrigation water. Salinity of water waslow and ranged from 0.00 to 0.05 dsm-1with EC from 64.30 to 104.50 μmhos which falls below the upper limit ofstandard for irrigation water (2,000 μmhos). Total suspended solids concentrations were from 9.00 to 13.00 mgl-1.These ranges are relatively low to medium compared to the standard limits and may pose no harm or threat to plantsirrigated or cause damage to pumps if screens are not used to exclude them. The anions: NO3-, HCO3-, CO32-, Cl- SO42-levels were however less than the upper limit for irrigation water. Therefore, the waters were highly suitablefor irrigation without improvement. Trace elements were 0.44 to 0.93 mgl-1for Fe, 0.03 to 0.12 mgl-1 for Mn, 10.00 to 14.00 mgl-1for Cd, 3.00 to 5.00 mgl-1 for Pb and 0.25 to 0.45 mgl-1for B (maximum application rates should notexceed that which allows normal crop growth as plant uptake is so small). In general terms therefore, qualities ofirrigation water in the study sites conformed to the specifications for irrigation water.