Effect of Algae Crusting Cover on Soil Structure Under Freeze-Thaw Conditions

Abstract

[Objective] To investigate the effects of biological crustal cover and freeze-thaw on soil structure. [Methods] The effects of different freeze-thaw times, initial soil water content before freeze-thaw and biological crusting (algae crust) cover on soil structure characteristics was employed to analyze the indoor simulated freeze-thaw method. [Results] (1) The soil structure index (IGSS) obtained by orthogonal experiment was between 75.57～96.57, the signal-to-noise ratio (S/N) was between 37.55～39.70 dB, and the optimal factor combination ascertained by the Taguchi method was 15 freeze-thaw cycles, 15% initial water content, and 80% algal crust coverage, and the predicted results were IGSS=98.09, S/N=39.89 dB. (2)A positive correlation was observed between IGSSIGSS was positively correlated with freeze-thaw times, initial water content and algal crusting coverage, and the primary influences on the soil structure index were ranked as initial water content > freeze-thaw times > algal crusting coverage. The contribution rates of each factor to alterations in the soil structure index were initial water content (52.17%) > freeze-thaw frequency (31.95%) > algae crusting coverage (2.12%). (3) The change of soil structure index comes from the loss of soil water and pore expansion during the freeze-thaw process, and algae crusting can slow down the loss of water during the freeze-thaw process, thereby decelerating the IGSS alteration. [Conclusion] Orthogonal experiments in this research explored the effect of algae crusting cover on soil structure under freeze-thaw conditions, and the results could provide a theoretical reference for the study of soil freeze-thaw process under complex conditions.

Keywords

• the loess plateau
• soil structure
• freeze-thaw simulation
• biological crust
• taguchi method