Humic Substances for Use in Remediation of Salt-Impacted Soils

This study looks at the impact of Humic Substances (HS) on the remediation of salt-impacted soil. Specifically, to evaluate the ability of different HS, including Nanobind, to reduce salinity levels in soil. In addition, the study evaluates the effect of HS on the leachability of sodium and chloride ions relative to control (unamended) and gypsum-amended soils. The study conducted a laboratory and growth chamber bioassay to investigate if HS can enhance the growth of selected salt-sensitive crops and to evaluate the impact of HS on salt and metal uptake in salt-impacted soils. Understanding the remediation potential of these amendments will allow the development of low-cost, eco-friendly remediation options of salt-impacted soil.

Our results showed that when salt-impacted topsoil marginally exceeds regulatory criteria it can be managed and put to agriculturally productive use by applying humalite or biochar combined with gypsum to the soil. When this amendment is followed by leaching with, at minimum, three pore volumes of water, it is an effective strategy for reclaiming sodic or saline-sodic subsoil of comparable mineralogy and texture. Boron removal from the salt-impacted subsoil using leaching was not as effective as that of salt because of the greater interaction of boron with the soil than chloride or sodium. Thus, for boron, one should consider risk-based site closure.