冻融循环恢复土壤压实过程中大孔隙作用研究

农机压实土壤的问题很难避免,而农田压实土壤的结构恢复至关重要,冻融循环是恢复压实土壤的有效方法。为了研究冻融循环+大孔隙对恢复压实土壤的作用,通过室内试验重塑压实土壤及人工孔隙措施模拟大孔隙,在不同土壤含水率条件下设计不同的冻融循环次数,利用温度传感器监测土壤温度波动,同时对比冻融循环前后压实土壤孔隙与团聚体参数的变化。结果表明,冻融循环过程中,有人工孔隙压实土壤在高、低两种含水率条件下,分别在第3次和第2次冻融循环时开始大幅温度波动,相同含水率条件下无人工孔隙的压实土壤温度大幅波动则出现在第7次和第4次冻融循环,经历多次冻融循环后,有人工孔隙压实土壤的团聚体平均尺度、结构系数等参数均优于无人工孔隙的压实土壤。人工孔隙可通过调节土壤温度波动改变冻融循环在土壤中的作用强度,加速压实土壤结构恢复进程,冻融循环+大孔隙策略是改善土壤孔隙及团聚体结构的有效措施。

Role of Macropores for Soil Compaction Restoring during Freeze-thaw Cycles

The problem of soil compaction by agricultural machinery is almost unavoidable, so structural restoration of compacted soils is essential and the freeze-thaw cycle is an effective method for restoring compacted soil. In order to study the role of freeze-thaw cycle + macropore on the recovery of compacted soil, the indoor experiments were carried out to remodel the compacted soil and simulate the macropore by artificial pore measures, the number of freeze-thaw cycles was designed to be different under two soil water contents, the temperature fluctuation of the soil temperature was monitored by using temperature sensors, and at the same time, the changes of the pore and aggregate parameters of the compacted soil before and after the freeze-thaw cycle were compared. The results showed that during the freeze-thaw cycle, the temperature fluctuation of the compacted soil with artificial pores started at three and two cycles under the conditions of high and low water contents, respectively, while the temperature fluctuation of the compacted soil without artificial pores under the same water content conditions appeared at seven and four cycles, and the average scale of the aggregate and the structure coefficient of the compacted soil with artificial pores were all better than those of the compacted soil without artificial pores after freeze-thaw cycles. Artificial pores can change the intensity of freeze thaw cycles in soil by adjusting the soil temperature fluctuation, and accelerate the process of structural recovery of compacted soil, i.e., the strategy of freeze-thaw cycles + macropores was an effective measure to improve the pore and aggregate structure of soil.