Field studies on leaching behaviour of a highly saline-sodic soil under two modes of water application in the presence of crops

Summary The leaching behaviour of a highly saline-sodic, moderately permeable, sandy-loam soil was evaluated under continuous and intermittent submergence conditions in a longterm field study in the presence of rice and subsequent wheat and sesbania crops. Leaching curves with respect to both desalinization and desodification showed that leaching efficiency was considerably higher with intermittent than with continuous submergence. The curves were useful in determining the amount of leaching water needed for a given mode of water application to reduce harmful levels of salinity and sodicity to acceptable ones. Empirical equations were determined to fit the experimental data. Their comparison with another empirical equation from published bare-field data of this site showed that leaching efficiency under crops was higher than under fallow. From the desodification leaching curve, it is concluded that in reclamation of these soils there is no need of the application of any amendment like gypsum. The soil salinity and sodicity data recorded at different growth stages and crop yields showed that leaching during the rice growing season, under intermittent submergence without previous leaching, decreased salinity and sodicity throughout the top 100 cm of the soil to levels safe for the successful cultivation of rice and subsequently the relatively deep-rooted crops of wheat and sesbania.