Saline soils are the main soil types in the Thai Binh province, which play an important role for agricultural production in the province as well as in Red river delta. Under the influences of climate changes, land use and others, saline soils in Thai Binh have been changing in both area and quality. The results for these soils in Thai Binh from 1987 to 2007 showed that total area of the saline soils increased 2,010.6 ha
of which the areas of the mangrove saline soil increased 1,600.8 ha, the strongly saline soil decreased 528.9 ha and the moderately and slightly saline soil increased 938.7 ha. By comparing the soil analysis data from the survey in 1987 and from survey in 2007, the quality of these soils was significant change after 20 years of using. For the strongly saline soil: Total salt dissolve and chlorine did not change. The pH value did not change in top soil layers, but it slightly decreased in other layers. The total nutrient contents such as organic matter and potassium increased, nitrogen did not change, potassium available decreased. For the moderately and slightly saline: Total salt dissolve and chlorine trend increased. The particle sizes of sand were increased, but limous and clay were decreased in both saline soils, because of influences of water regime. The pH value decreased in top soil layers, but it did not change in other layers. The total organic matter, nitrogen and cation exchangeable capacity were decreased, because of water regime. Total potassium and available potassium increased. Because of annual alluvial irrigation and add a lot chemical fertilizers.