季节性冻融后机械压实黑土自然恢复特征

以东北典型黑土区机械压实的耕地土壤为研究对象,通过对一季冻融交替后土壤团聚体MWD、PAD0.25、土壤容重、孔隙结构以及广义土壤结构指数等指标的测定和分析,对比研究了季节性冻融对耕作区不同程度压实黑土结构的影响及其自然恢复特征。结果表明:季节性冻融能够加剧黑土风干团聚体的分散并促进水稳性团聚体的团聚、降低破其坏率,以碾压2次处理时最为显著,破坏率降低了24.57%;且两种作用均随着碾压次数的增加逐渐削弱,经冻融交替改善的土层范围也随着碾压程度的增加,逐渐上升缩减至地表。季节性冻融能够不同程度地缓解并改善典型黑土耕作区压实土壤的容重、NCP/CP以及土壤三相结构,但碾压超过8次时土壤结构无法恢复至自然无压实的状态;由于不同压实程度土体内水热运移的差异而致,土壤结构表现出不同的恢复特征,压实2次冻融后的容重、NCP/CP分别显著降低和增加了6.97%和58.79%,GSSI却相对降低了2.28%。

Natural recovery of black soil compacted by machinery after seasonal freeze and thaw cycles

Based on machinery-compacted soil in a typical black soil region,the effects of seasonal freeze-thaw cycles on soil structural and natural recovery characteristics were analyzed by measuring MWD and PAD0.25 of soil aggregates,soil bulk density,porosity and generalized soil structure index.Results show that seasonal freeze-thaw cycles can enhance the separation of dry aggregates while it can strengthen the aggregation of water stable aggregates and lower its percentage of disruption.In particular,when soil i...