Nitrate Leaching from Soils as Influenced by Rate and Timing of Potassium Nitate Application

The kinetics of leaching of nitrate (NO3−) in agricultural and non-agricultural soils was studied on undistributed columns using alkaline soil (pH = 8) of Kota region of Rajasthan. Potassium nitrate (KNO3) was used as a source of NO3−. Power form equation (LRobs = k [NO3−]i1.49 for agricultural and (LRobs = k [NO3−]i1.72 for non-agricultural soils) have been derived for dependence of LRobs on leachable concentration of NO3− present initially in the column during leaching. Effects of pore volume, temperature, Ca hardness and Na level of extractants have been observed on leaching rate. Change in water filled porosity θ (cm3 cm−3) of the column has been found to affect LRobs. An increase in temperature in the range 25–50°C has increased LRobs. Experimental data fitting on various kinetic models showed first order kinetic models and parabolic diffusion to be most suited for predicting leaching rates.