Remediation of saline soil from shrimp farms by three different plants including soybean (Glycine max (L.) Merr.)

Abstract

Shrimp farm activity can elevate in-situ soil salinity that in turn may affect any subsequent crop production if land usage changes. The utility of three different plants viz. soybean (Glycine max (L.) Merr.), narrowleaf cat-tail (Typha angustifoliaL.) and sea holly (Acanthus ebracteatus Vahl) for phytoremediation of saline soil derived from former shrimp farmactivity was investigated. The latter two species have been categorized as halophytes. In experiments of 16 days’ duration and using sodium chloride concentrations (50–70 mg g−1 dry weight) similar to those found in the benthic material of shrimp farms in Nakhon Pathom Province, central Thailand, the bioconcentration factors of sodium chloride (BCF; g soil dry weight g−1 plant dry weight) in soybean (2240–4840) were found to be significantly higher than those found for narrow leaf cat-tail (16–20) and sea holly (15–17) at p<0.05. The translocation of sodium chloride from root to shoot was noted in all plant species investigated, as well as wilting and defoliation due to the effects of sodium chloride. Approximately 90%, 70% and 60% removal of sodium chloride in root zone soil was observed after growing soybean, narrow leaf cat-tail and sea holly, respectively. Soybean plants thus showed the greatest ability to decrease soil salinity, with measured root zone soil conductivity levels falling from 16.4–18 dS m−1 (characteristic of strongly saline soils) to 1.5– 2.1 dS m−1 (weakly saline). Although an important economic crop, soybean may also have potential in soil remediation.