Assessing Leaching and Salt Balance in the Reclamation of Sodic Soils

The study was conducted on two 4 m x 4m plots of saline-sodic soils, designated as plot 1B having medium textured loamy surface with very slowly permeable subsoil and plot IIA light textured silt loamy surface with slowly permeable subsoil. Leaching and salt balance were assessed from the analysis of different parameters of salt inflow and outflow from the soil. Bulk of the salt movement occurred during the kharif rice grown under water submerged condition, practically nil during the rabi wheat and somewhat increased during the following monsoon grown green manuring crop. Salts leached from the surface soil were deposited in the 60 cm subsoil of plot 1B but deeper in plot IIA. The salt leaching fractions were 0.520 and 0.685 from 30 cm depth of plot IB & IIA respectively which reduced to 0.158 and 0.412 as soil depths increased to 90 cm. Disposal through flushing was small but significant. Leaching decreased with soil depth approaching zero at 167 cm depth in plot IIA but stopped at 116 cm in heavier soil, not deep enough to affect ground water quality. By employing tritium tagged estimated ground recharge, some of the mathematical models could be used to predict salt leaching which gave comparable results obtained from the experimentally determined salt balance equations.