Residual Effect of Malathion (Organophosphate) and Sevin (Carbamate) Application on Potato ( Solanum tuberosum )

An experiment was conducted at Shambat Agricultural farm to study the effect of pesticides residues on soil and potatoplant. Potato was planted on January, 2009 on ridges with a spacing of 70 cm between rows and 10 cm between plants. Sevin and Malathion pesticides were added at different concentrations to evaluate their effect on the plant growth and soil. The measurement taken was plant height (cm), fresh and dry weight (gm), leaf area (cm2), pH, total nitrogen %, phosphorus (ppm), leaf number and size of tubers. The results revealed that both chemicals affected negatively the vegetative growth of potato and its yield. It was noticed that the yield was generally less due to the effect of the heavy clay soil of Shambat. Addition of Sevin increased the total soil nitrogen and reduced soil organic carbon while the reverse was noticed for Malathion. Both chemicals lowered soil pH, from alkaline to neutral or slightly alkaline. However, they increased soil salinity which in turn affected potato growth and yield.