Soil salinity reduction and prediction of salt dynamics in the coastal ricelands of Bangladesh

Field experiments were conducted in moderately saline and saline soils during the 1996 dry and wet seasons and the 1997 dry season to document salt dynamics and establish their relationship with local hydrology. Topsoil (0-15 cm) salinity in the dry season varied from 4.0 to 9.0 dS m(-1) in moderately saline soils at Mirzapur and from 5.0 to 12.0 dS m(-1) in saline soils at Barodanga. In wet season, the corresponding figures were from 1.5 to 2.5 dS m(-1) and from 2.0 to 3.0 dS m(-1) respectively. Dry season cropping significantly reduced topsoil salinity at both the research sites. Overall peak salinity in non-plowed cropped lands was 25-38% lower than that of fallow lands, and in plowed cropped lands it was about 30-40% less than the non-plowed cropped lands. Multiple linear and non-linear regression models were developed to predict topsoil salinity of the fallow land for both moderately saline and saline soils by using daily rainfall and evaporation as independent variables. The prediction level was not significantly improved when a non-linear model was employed in place of linear model. Therefore, a linear model may be used to predict topsoil salinity of the coastal ricelands of Bangladesh. (C) 2001 Elsevier Science B.V. All rights reserved.