Simulating Swine Manure Transport in Soils Using the Mobile-Immobile Contaminant Transport Model

Abstract

Modeling swine manure transport is an important initial step not only in understanding the behavior of this potential contaminant in the subsurface environment but also in providing a basis for appropriate management schemes. This study was carried out to estimate the solute transport parameters in Nicollet silt loam in Iowa and to consequently perform simulation of swine manure transport using the two-region, mobile-immobile, non-equilibrium contaminant transport model. Laboratory soil column and lysimeter miscible displacement experiments were performed using swine manure as tracer and using electrical conductivity as a measure of chemical transport. The solute transport parameters were measured based on experimental data and optimized using CXTFIT. The mobile-immobile contaminant transport model for predicting swine manure transport fitted the observed breakthrough curves better under laboratory conditions (R2=0.956) than under field conditions (R2=0.763) for the soil dealt with. Of all model parameters, the scaling effects were most pronounced for the dispersion coefficient. Results of this study proved the applicability and adequacy of the two-region (mobile-immobile) nonequilibrium contaminant transport model for predicting the transport of swine manure in soils.