The Main Ion Concentrations in Surface Soil Layer in Nam Dinh Province of the Red River Delta, Northern Vietnam

Abstract

Abstract:This study aims to clarify the main ion concentrations in paddy field surface soil from 0 to 100 cm in depth along the coast of the Red River Delta, Northern Vi etnam, represented by Nam Dinh Province. There is a relation between total dissolved solid (TDS) and Na+ concentra tion. Na+ and Cl concentrations in paddy fields increase gradually and the abundance of Cl concentration in soil proclaims the influence of seawater intrusion. Washing is reported to reduce the high salinity in the cultivation-layer soil of paddy fields. Furthermore, the impact of seawa ter intrusion on soil salinity of coastal paddy fields has been considered. The top soil layer of coastal salt-affected paddy fields has the highest sodium absorption ratio (SAR) values, and shows the strongest salinity influence in both the flood season and the dry season. Soil samples near the Day River mouth have high SAR values with considerable Na+ concentrations in the dry sea son. The exchange selectivity between Ca2+, Mg2+ and Na+ has also been studied by considering changes in the SAR under different conditions of soil composition and land cover. In coastal agri cultural land, the SAR in the surface soil layer can be used to evaluate the influence of salinity. The SAR in cultivated soil is used to assess the influence of salinity problems on the paddy field.

Problem Soils of the Paddy Fields in the Eastern Coastal Plain of the Red River Delta, Vietnam

“…On the other hand, in the tide-dominated delta, the top soil layer has high sulfur and aluminum concentrations in an acidic environment (Dinh and Haruyama, 2002, Dinh et al, 2003, 2004, 2005 .…”

“…Dinh et al (2006) studied the main ion concentrations in surface layer of soils in Nam Dinh Province of coastal area of the Red River Delta and clarified the relation between total dissolved solid and Nat.…”