Soil Water Evaporation as Affected by Wetting Methods and Crust Formation
1970
Bresler, E. | Kemper, W. D.
Laboratory studies showed that evaporation from soil columns which were wetted by flooding was 25–30% higher than soil wetted by rain and 30–40% higher than from soil to which NaCl was applied prior to wetting by simulated rain. About 25–35% more water evaporated from soil which was exposed to evaporation immediately following infiltration compared to soil which exposed to evaporation 4 days after infiltration ceased. The crust which was formed at the soil surface by the raindrop action and dispersion due to sodium ion caused the wetting rate to decrease from 23 cm/hour in the flooded treatment to 1.1 in the rain and 0.06 cm/hour in the rain on NaCl treatment. Higher water content profile and shallower wetting zone resulted when rates of wetting were faster, and caused the total water loss to be higher. The total water loss was also affected by the type of crust which formed at the soil surface. After from 1 to 4 hours of evaporation, the highest resistance to water flow was estimated in the region immediately below the crust. This high resistance region hastened the formation of a surface dry layer in the rain-wetted treatments which reduced evaporation.
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