冻融条件下藻结皮覆盖对土壤结构的影响

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

[目的]为研究生物结皮覆盖和冻融作用对土壤结构的影响。[方法]以黄土高原北部风沙土为研究对象,采用室内模拟冻融的方法,利用田口方法分析不同冻融次数、冻融前土壤初始含水量和生物结皮(藻结皮)盖度对土壤结构特征的影响。[结果](1)通过正交试验获取的土壤结构指数(I GSS)为75.57~96.57,信噪比(S/N)为37.55~39.70 dB,通过田口方法确定的最佳因子组合为15次冻融循环、15%初始含水量、80%藻结皮覆盖度,其预测结果为I GSS=98.09,S/N=39.89 dB。(2)I GSS与冻融次数、初始含水量、藻结皮盖度均呈正相关关系,各因子对土壤结构指数的主效应表现为初始含水量>冻融次数>藻结皮覆盖度;各因子对土壤结构指数变化的贡献率为初始含水量(52.17%)>冻融次数(31.95%)>藻结皮覆盖度(2.12%)。(3)土壤结构指数的变化来自于冻融过程中土壤水分的散失和孔隙扩张,藻结皮覆盖可以减缓冻融过程中水分的散失,从而减缓I GSS变化。[结论]研究使用正交试验对冻融条件下藻结皮覆盖对土壤结构的影响进行探讨,研究结果可为复杂条件下的土壤冻融过程研究提供一定的理论参考。

[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(I GSS)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 I GSS=98.09,S/N=39.89 dB.(2)A positive correlation was observed between I GSS I GSS 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 I GSS 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.