A long term (1990-2000) soil and water salinity monitoring programme was undertaken to address the salinization problem in paddy cum brackish water shrimp cultivation area . The information generated during this period has been presented in this paper. In monsoon season, particularly from August to October soil salinity had increased from 1.4 dS/m to 10.3 dS/m. In between November and February depth of ground water table remained within 0.12 m to 0.33 m and rest of the year it remained at or close to the surface. So, due to presence of ground water table at shallow depth and slower permeability downward movement of soluble salts from the top is very limited. Under Pashur river system average submerged water salinity was found to be 13.8 dS/m to 17.5 dS/m in between March and- May. In Shibsha river system it was found to be 13.2 dS/m to 24.2 dS/m in between February and June. More soluble salts have been accumulated in the topsoil over long period brackish water shrimp cultivation. Increasing tendency of soil pH from 7.5 to 8.2 may be due to high amount of cations like Ca, Mg, and K. High amount of S may be one of the possible reasons for P deficiency in brackish water submerged condition. Soils are rich in B. Cu, Fe except Zn. Late transplantation, without or very little fertilization, without insecticides, use of aged seedlings, wider spacing, relatively high flooding at the time of aman transplantation, minimum tillage and little opportunity of flushing and leaching of fresh water are the common constraints of paddy cultivation in paddy cum brackish water shrimp cultivation area.

A five year project was undertaken to address the salinity problem in the upstream of Baleswar river. The information generated during this period have been presented in this paper. Previously the Madhumati-Baleswar river system was completely non saline throughout the year. Recently upstream fresh water flow from the Madhumati river through the Baleswar river passing in between Chitalmari and Nazirpur Upazila is about to cease due to prolonged siltation on the river bed. During intensive monitoring work (1995-1999) some canals such as the Chitra river, Vasa canal, Santoshpur canal, Lara canal etc. are identified as the portals of saline water in the upstream of the Baleswar river in dry season. Due to tidal effect they carried saline water from Daratana river to Baleswar river. As a result high water salinity prevailed in Baleswar river in between February and May. Maximum water salinity ECw 17.6 dS/m and soil salinity ECe 4.4 dS/m were recorded in May. Water extraction for irrigation in the riparian area was restricted due to high salinity. To minimize this salinity problem upstream fresh water flow from the Madhumati river to the Baleswar river has to be increased. Increased volume of upstream fresh water flow will push saline water back to downward direction. The major portals namely Chitra river and Vasa canal may be closed seasonally by constructing sluice gate with proper engineering design to prevent entry of saline water in the Baleswar river.