[Effects of freeze-thaw cycles on aggregate stability of black soil].

The stability of 3-5 mm aggregates of black soil collected from Heilongjiang Province were analyzed by Le Bissonnais method under different freeze-thaw cycle treatments (0, 1, 3, 5 and 9). The aggregate porosity were measured by wax-coated method. The results showed that the contents of different size aggregates fluctuated with the freeze-thaw cycles, and the variation coefficient of aggregate content turned stable gradually. There were significant differences of the content of above 0.25 mm aggregate among the treatments of fast wetting, slow wetting, and wet stirring. Aggregate porosity increased with increasing freeze-thaw cycles, ranging from 32.4% to 41.4%. Low variation of aggregate contents occurred in different breakdown patterns with increasing freeze-thaw cycles. There was negative correlation between porosity and mean weight diameter, suggesting the aggregate porosity was important in the aggregate stability under freeze-thaw condition.应用Le Bissonnais法分析冻融循环(0、1、3、5和9)对3～5 mm黑龙江省黑土团聚体稳定性的影响,采用蜡封法分析黑土孔隙度的变化.结果表明: 不同粒径团聚体含量随冻融循环次数增加均呈波动状态,团聚体含量变化系数随冻融循环次数的增加逐渐趋于稳定;快速湿润、慢速湿润、预湿润震荡3种处理土壤中＞0.25 mm团聚体含量有明显差异;孔隙度随冻融循环次数的增加而增大,变化范围在32.4%～41.4%.随冻融次数的增加,不同破碎方式下团聚体含量变化程度较低,团聚体平均重量直径与孔隙度呈负相关,表明冻融条件下孔隙度是影响团聚体稳定性的重要因素.