Salinity Status of Osere River for Irrigation: Long Term Use Implication in Selected Farmers’ Field in Ilorin, Nigeria.

Osere River is one of the important rivers that serves as a cheaper and easier disposal alternative to industries and at the same time a less expensive and dependable water supply to farmers for dry season vegetable production in Ilorin, the capital city of Kwara State, Nigeria. The edaphic aftermath of the use of its water for irrigation was investigated using a Randomized Complete Block Design (RCBD) in a two way factorial experiment. Factors comprised of fifty meter distance intervals (50 and 100 m) downstream and a control (50 m upstream) of a soap industry effluent discharge point and irrigation duration (0, 10, 20 and 30 years). River water samples indicated that the activities of the soap industry did not lead to its increased electrical conductivity (which signifies presence of dissolved salts and/or impurities), however soils under prolonged irrigation (up to 10 years) showed signs of salt induced structural deterioration (MWD). Farm soils 50 m downstream showed the lowest structural stability (MWD = 0.77 mm)and highest % silt of 21.2 whereas those located 100 m downstream indicated highest MWD of 1.10 mm. The consequent soil structural degradation was tied to elevated values of sodium adsorption ratio (SAR) following prolonged irrigation.