Effect of Water Quality and Drying on Soil Crust Properties

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Abstract
The effect of soil crust and drying on the infiltration rate of Calcic Haploxeralfs (Loess) and Typic Rhodoxeralfs (Hamra) was studied using a rainfall simulator. The soils were exposed first to a rainfall of water with low electrolyte concentration [electrical conductivity (EC) ≃ 0.01 dS.m−1] until a steady state infiltration rate was obtained. Thereafter, the crusted soils were dried for different periods of time (24, 48, 72 and 96 h). After drying, the soils were saturated from beneath with tap water, then subjected to a second storm of either water with low electrolyte concentration (EC ≃ 0.01 dS m−1) or saline water (EC œq 5 dS m−1). Drying the crust increased the infiltration rates of the soil in the second storms, and increased its sensitivity to the salinity of the applied water. The results suggest that drying the crust caused its' breakdown, due to both the formation of cracks and the formation of new structure at the soil surface. Drying the crust brings the soil particles, which form the crust, closer together creating a new structure. The new structure at the soil surface makes the soil surface more permeable and more sensitive to the destructive action of the raindrops.