Heat,Water, and Solute Transfer in Unsaturated Porous Mdeia: II -- Compacted Soil Beneath Plastic Cover

Soil surface dynamics involve coupled transferof heat, water, and solute. An experimental andtheoretical study of heat, water, and solute transferin closed compacted soil columns under surfacetemperature wave amplitudes is presented. Thetemperature wave amplitudes ranged from 17.9 to 21.0°C. Potassium chloride solution was used tomoisten Clarinda clay and Fayette silty clay loamsoils. Initial water contents of 0.403 and 0.279 andinitial solute concentrations of 0.062 and 0.052 mol kg^-1were used in Clarinda and Fayette soils,respectively. The moistened soils were packed andcompacted in PVC columns (0.075 m diameter and 0.30 mhigh). Bulk densities of the compacted Clarinda andFayette soils were 1403 and 1585 kg m^-3,respectively. The columns were buried in soil suchthat column surfaces were exposed to natural as wellas artificial radiation and thermal conditions. Thecoupled nonsteady-state balance equations of mass andenergy were solved numerically to predict soiltemperature, water content, and solute concentrationdistributions. The theoretical model described soiltemperature, water content, and solute concentrationwell as compared with the measured values. TheFickian diffusive solute flux was one or two orders ofmagnitude greater than salt-sieving and thermal-diffusion solute fluxes.