冻融过程对黑土水稳性团聚体含量影响

The Effect of Freezing and Thawing Processes on Black Soil Aggregate Stability

以黑土为试验材料,通过室内模拟试验,研究了冻融过程中含水量、温度、循环次数等因素对黑土团聚体稳定性的影响.结果表明:田间持水量(40%)时的冻融过程增强团聚体稳定性,含水量过高或过低均破碎团聚体,特别是高含水量(70%);冻结温度对团聚体稳定性也有显著影响,含水量条件是适宜冻结温度的先决条件;随冻融循环次数增加(1次、7次和14次)各级团聚体含量(>0.5mm)、团聚体总量和平均重量直径降低.在此基础上,针对含水量对团聚体稳定性效应的研究争议,提出冻融过程团聚体稳定性的土壤水气矛盾统一体假设.建议在黑土冻结前,调节土壤含水量至田间持水量,从而保持和改善土壤物理结构.

Laboratory experiments were carried out to investigate the effect of freezing and thawing on wet aggregate stability （WAS） of black soil, including the effects of different aggregate size groups, different water contents and various freezing and thawing cycles and freezing temperatures. The re sults showed that WAS is greatest at field water capacity （40%）, and less at higher or lower water content, especially at higher water content （70 %）. The freezing temperature also has a significant influence on WAS, but the water content is a predominant factor to a suitable freezing temperature. The mean weight diameter, water stable aggregates （〉0.5 mm） and the total contents decrease with freezing and thawing cycles increasing. The reason for crumbing aggregates is the water and air confliction. A hypothesis explaining how the water content affects the aggregate stability in the process of freezing and thawing is put forward.