Soil Properties of Balat Estuary, Giao Thuy District, Nam Dinh Province

Thí study was carried out to determine soil properties and for soil mapping of Ba Lat estuary. The main methods applied are soil servey, soil analysis, and soil classification according to FAO. The results showed that soils of Ba Lat estuary, Giao Thuy district were divided into 3 soil groups with 5 soil units, including 5 soil sub-units. Salic Fluvisols group has largest area of 7,498.01 ha, accounts for 77.61% of total surveyed area and nearly 50% of total natural area. Typical character of salic fluvisols of Ba Lat estuary, Giao Thuy district is various soluble salt concentration. More than 71% of salic fluvisols has high salinity which has total soluble salt greater than 0.5%; the rest has medium and low salinity, with total soluble salt less than 0.5%. Salinity comes from chloride. Total concentration of substances varies from medium to rich. Fluvisols group has only 1,859.16 ha, accounts for 19.24% of total surveyed area. Fluvisols of Giao Thuy district is typical with light to medium soil texture, rich total nitrogen and total phosphorous, medium potassium. Acidity from light acid-medium to light alkaline. Entire area is slightly saline. Arenosols group has smallest area of 303.71ha, accounts for 3.14 of total surveyed area or 2% of district’s total natural area.  Arenosols of Ba Lat estuary, Giao Thuy district has very light soil texture (the main content is sand), medium acidity, poor nutrients and low cation exchange capacity, normally less than 3 meq/100g soil.