The Effect of Soil Salinity and Sodicity on Soil Erodibility, Sediment Transport and Downstream Water Quality

There is an abundance of literature on many aspects of soil salinity and sodicity, and the impact of increased salt and sodium on properties, behaviour, management and productivity of soils. However the impact of sodicity on erosion and soil erodibility and sediment transport has received less attention. The aim of this study was to investigate the effects of changing soil salinity and sodicity of two Queensland soils on their erodibilities and erosion losses under simulated rainfall. Erosion measurements were carried out on the two soils in the 1 x 6 m flume of Griffith University's large rainfall simulation facility (GUTSR), with and without sodium treatments. Sediment loss increased for both sodium-treated soils with the Redlands soil showing an eight-fold increase. Mean aggregate/particle size of the eroded sediment decreased with increased sodicity. High sodium concentration thus contributed to the weakening of soil aggregates and their dispersion under the raindrop impact. Electrical conductivity and salt concentration of the runoff decreased exponentially with time from sodium-treated soils. Additional