Modification of soil physical properties by manipulating the net surface charge on colloids through addition of Fe(III) polycations

Summary The addition of 0.07 per cent Fe in the form of polycation of molecular weight 10000–50000 flocculated soil suspensions. Higher concentrations of Fe(III) caused redispersion of the clay. Electrophoretic and electron microscopic studies confirmed the flocculation‐dispersion phenomena. The soil suspensions with higher concentrations of Fe(III) gave points of zero charge (PZC) between pH values 5.0 and 6.0. The flocculation resulted in microaggregation and created pores 40–100 μm in diameter. This led to an increased water‐holding capacity and hydraulic conductivity and lower bulk densities and modulus of rupture. The soils treated with Fe(III) polycations were shown to be more friable than untreated soils.