EFFECT OF WATER CHEMISTRY AND SOIL AMENDMENTS ON A SILT LOAM SOIL - PART 1 - INFILTRATION AND RUNOFF

Infiltration, runoff and soil loss are processes that occur when rainf all and runoff water interact with the structure and physical and chem ical bonds of the soil surface. A well-aggregated soil which is strong ly resistant to dispersion and aggregate breakdown, and which is fairl y porous, will typically have greater infiltration rates and less runo ff and soil loss than a poorly aggregated soil that is easily disperse d and which seals and crusts. Soil surface seal formation results from : physical breakdown of soil aggregates due to raindrop impact, and/or chemical dispersion which is dependent upon soil properties and the e lectrolyte concentration in the surface water solution. This study exa mined the effect of electrolyte concentration in rainfall and runoff w ater as well as the effect of different soil surface amendment treatme nts on infiltration, runoff and soil loss from a typical silt loam soi l susceptible to aggregate breakdown and sealing. This article present s the infiltration and runoff results, and a companion article present s the soil erosion results. Rain water electrolyte content was found t o have no significant effect on final runoff or infiltration rates. Th e use of a fluidized bed combustion bottom ash (a byproduct from coal- fired electric power plant emissions desulfurization) soil surface ame ndment significantly increased infiltration on small interrill areas ( 41.9 mm/h vs 32.2 mm/h for the control), but was less effective on lon ger rill plots (20.6 mm/h vs 18.4 mm/h for the control, difference not significant). Addition of a small amount of an anionic polyacrylamide in tap water used as simulated rainfall greatly increased water infil tration into the soil, which may have potential application in sprinkl er irrigation systems.