Salinity and Compaction Effects on Soil Water Evaporation and Water and Solute Distributions

Abstract

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, mixed, mesic Typic Hapludalf) — and three conditions. Two conditions were 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 were 0.271 and 0.181 m3 m−3 for noncompacted Clarinda and Fayette soils, respectively. The initial soil water content of compacted Clarinda was 0.393 m3 m−3 The initial KCl concentrations were 1.11 and 0.92 mol 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 water 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 for 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.

Nonlinear effects of salt concentrations on evaporation from porous media

“…For instance, Shimojimaa et al [1996] reported that in the presence of water table, the evaporation rate from silica sands and glass beads saturated with NaCl solution of ∼0.3 molal (i.e., moles of salt per kilograms of water) was reduced 70% and 30%, respectively, compared to the evaporation rate from pure water. Nassar and Horton [1999]also reported reduction of the evaporation rate due to the presence of KCl in water. Despite the fact that areas such as salt‐affected lands, salt marshes, and salt lakes may contain high salt concentrations, most of the previous evaporation studies focused on the situations in which salt concentrations were relatively low and very few studies attempted to quantify the evaporation process from porous media saturated with highly saline solutions.…”

Maximum surface temperature model to evaluate evaporation from a saline soil in arid area

“…The low osmotic potential reduced the vapor pressure in saline soil, which can reduce evaporation. Nassar and Horton (1999) found that evaporation from saline soils varied from 78 to 95% of the evaporation from non-saline soils.…”

On the effectiveness of dry drainage in soil salinity control

“…In terms of sustainability, more attentions should also be paid to it since the continuously accumulating salt in the fallow area perhaps has significant effects on soil physical properties and therefore on evaporation during its long run. Experiments show that water transfer is reduced in salinized soils [13][14][15][16] . Numerical simulation shows that the lifetime of a dry drainage system could be a few years before the pores in the top 0.5 mm soil layer are plugged by the precipitated salt and the evaporation stops [9] .…”