Influence of a polyacrylamide soil conditioner on runoff generation and soil erosion: Field tests in Baringo District, Kenya

Abstract Following promising laboratory results the effect of low concentration applications of a polyacrylamide soil conditioner SEPARAN AP30 on soil properties was tested under field conditions in a severely degraded semi-arid region in northern Kenya. Tests of conditioner performance on tilled and undisturbed soils were carried out under simulated rainfall on crusting Eutric or Calcaric Fluvisols at two sites on alluviolacustrine flats adjacent to Lake Baringo. Tests were carried out in two series separated by up to six weeks of sunshine and natural rainfall, to determine the longevity and residual effects of conditioner application. Runoff generation and soil loss were significantly reduced on all runoff plots during the first rainfall simulation, but the most dramatic results occurred when conditioner application was combined with raking. This inhibited crust development and virtually eliminated runoff and soil loss. Under natural weathering, surface crust had developed on all plots before the second rainfall simulations. Some residual effects of the conditioner on infiltration rates were still noted, but the residual effect on soil loss was greatly diminished. The tests indicate that low concentration applications of SEPARAN are not useful on undisturbed soils, but can provide useful temporary reductions in sheet and rillwash hazard when combined with tillage and could be effectively combined with grass re-seeding for more permanent reclamation.