Abstract: For the issues of brackish water capacity of soil salt content for safe irrigation in the low plain around the Bohai Sea, it is expounded that characteristics on the soils profile of different salinity accumulation types are that distribution of soil salt content is accumulation in the upper of the soil profile, or in the middle of the soil profile and in bottom of the soil profile. The formation of different salinity poly types are with evaporation, infiltration of rainfall or irrigation and water table depth change related, according to the data from the field monitoring and sampling. The formation of different characteristics of these polymer profiles are in different hydrodynamic condition. The soil moisture potential gradient profiles point to the surface, its absolute value is much larger than 1.0 cmH₂O/cm with the formation of salt accumulation to the upper of the soil profile. The soil moisture potential gradient point to groundwater table in the upper of the profile and point to the surface in bottom of the profile with the formation of salt accumulation to the middle of the soil profile. The soil moisture potential gradient profiles point to groundwater table, its value is much larger than 1.0 cmH₂O/cm with the formation of salt accumulation to the bottom of the soil profile. The brackish soil is not suitable for land and crops irrigation using slightly salty water.

Key words: Bohai Sea plain, groundwater, soil, salt, soil moisture potential