Salinity and compaction effects on soil water evaporation and water and solute distributions

Water evaporation and solute transport were studied in open soil columns. The study included two different soil materials - Clarinda clay (fine, montmorillonitic, mesic, sloping Typic Argiaquoll) and Fayette silty clay loam (fine-silty, mired, mesic Typic Hapludalf) and three conditions. Two conditions mere noncompacted solute-free and salinized noncompacted soil columns of both Clarinda and Fayette soils, and one condition was compacted salinized soil columns of Clarinda soil only. The initial soil water contents sere 0.271 and 0.181 m(3) m(-3) for noncompacted Clarinda and Fayette soils, respectively; The initial soil water content of compacted Clarinda,vas 0.393 m(3) m(-3) The initial KCl concentrations were 1.11 and 0.92 mot kg(-1) of soil solution for Clarinda and Fayette soils, respectively. Measured ratios of evaporation loss from the noncompacted salinized soil columns to the amount of eater evaporated from noncompacted solute-free soil columns increased with time from 0.78 to 0.89 for Clarinda and 0.90 to 0.95 for Fayette soils. Evaporation from noncompacted Clarinda soil increased with time from 0.73 to 0.77 of the evaporation from compacted Clarinda soil. A numerical model of heat, water, and solute transfer was used to predict distributions of temperature, water content, and solute concentration for a given evaporation rate. Efficiency of the model fur reproducing the water content and solute concentration ranged from 94.5 to 61.1%, The predicted and observed solute concentrations increased with time in the upper 0.02 m of noncompacted soil. Also, the upper soil portion, the 0.05-m layer, dried drastically. Both observations and predictions indicate complex interactions between heat, water, and chemicals near evaporating surfaces.