Studying the Effects of Biocrusts on Soil Water Dynamic and Evaporation

Biocrusts affect several soil hydrological properties such as soil water dynamic and evaporation. The aim of this study was to explore the effects of biocrusts on soil water dynamic and evaporation as a function of time. Soil sampling carried out from saline soil mass and biocrusts (undisturbed along with 5 cm underneath soil) from Qara Qir rangeland. To conduct experiment in a controlled condition, four plastic columns (20 cm d × 50 cm h) were prepared and filled up to 48 cm and 6 columns up to 43 cm with uniform saline soil mass collected separately from bare soils of study area, then a layer of intact BSCs (with 5 cm thickness) was put on the top of soil columns. Daily evaporation rates were measured with electronic balance weightings during 142 days. soil water content was determined three times in days of 17, 50 and 103 after experiment onset in any columns, at depths of 10 (D1), 20 (D2), 30 (D3) and 40 (D4) cm. The results showed that BSCs prevent water evaporation from soil surface, particularly at high evaporation demand (up to 77 days). The effect of BSCs on the evaporation rate at low atmosphere demand (77 to 142 days) was insignificant. Soil water content followed evaporation trend. According to these findings, it can be concluded that the BSCs as soil surface coverage is a key factor for reducing evaporation and conserving water in the soil.