Surface seal hydraulic conductivity as affected by livestock manure application

An infiltration model was developed based on Green-Ampt flow theory to describe infiltration of livestock manure into a uniform soil profile topped by a thin surface seal. The model incorporated the concept of effective hydraulic conductivity and allowed for either a constant or developing seal. Conductivity parameters associated with the seal and subseal layers were fitted to infiltration data obtained from soil columns in which a seal had formed due to exposure to simulated rainfall. Model results using the fitted parameters for both developing and stable seals were excellent when compared to observed data. Fitted crust conductivity parameters were examined to determine the effects of swine and dairy manure applications on surface-sealing of two soils. The stable seal conductivity parameter for columns receiving manure application was significantly greater than the respective parameter for Control columns, with the exception of swine manure incorporated into silt loam soil. Greater seal conductivity may be attributed to more organic matter on the soil surface, which improved aggregate stability and protected the surface from the energy of impacting raindrops.