植被恢復對典型黑土表層土壤壓縮性和承載能力的影響1)

韓少杰　王恩姮　羅松　陳祥偉

(東北林業大學，哈爾濱，150040)

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植被恢復對典型黑土表層土壤壓縮性和承載能力的影響1)

韓少杰王恩姮羅松陳祥偉

(東北林業大學，哈爾濱，150040)

以恢復年限分別為14、36、50 a的落葉松人工林及相鄰耕地表層土壤(0～10 cm)為研究對象，采用快速固結試驗法，對土壤孔隙比、壓縮指數、先期固結壓力等指標進行測試，分析植被恢復對典型黑土表層土壤壓縮性、承載能力的影響。結果表明：土壤孔隙比、壓縮指數、先期固結壓力，均隨恢復年限的增加而增加，壓縮指數、先期固結壓力變化范圍分別為0.231～0.399、4.2～100.0 kPa。落葉松林地土壤壓縮指數、先期固結壓力，均顯著高于耕地土壤(p<0.05)；隨植被恢復年限的增加，典型黑土表層土壤壓縮性、承載能力逐漸提高，耕性有所增強。土壤力學性質指標與理化性質之間，表現出顯著的相關性(p<0.05)；壓縮指數與土壤黏粒比例、有機質質量分數之間關系更為緊密(p<0.01)；先期固結壓力與土壤黏粒比例呈極顯著負相關(p<0.01)。植被恢復導致土壤有機質質量分數的增加；土壤密度和黏粒比例的降低，是黑土表層土壤壓縮性增加、土壤承載能力增強的重要原因。

植被恢復；黑土；土壤；土壤壓縮性；土壤承載能力

To explore the changes of black soil’s compressibility and load support capacity in the restoration process, we took the topsoil (0-10 cm) in typical black soil region with vegetation restoration of 14, 36 and 50 years and the nearby farmland as test objects. We used fast oedometer test to measure and calculate soil mechanical parameters, soil void ratio, the compression index and the pre-compression stress. The soil void ratio, compression index, and pre-compression stress were increased with the increasing year of vegetation restoration. The values of compression index and pre-compression stress were varied in 0.231-0.399, 4.2-100.00 kPa, respectively. The compression index and pre-compression stress of soils at different age larch plantations were significantly higher than those of tillage soil (p<0.05), that is, the compression index, pre-compression stress and the tilth of soil were increased with the increasing of recovery years. The soil bulk density, clay proportion decreased and the mass fraction of organic matter were increased with the increasing of recovery years, and good linear regressions were between bulk density, clay proportion, the contents of organic matter and soil mechanical properties. Bulk density had a negative influence on compression index (p<0.05), the correlation between the contents of organic matter, clay proportion and compression index were closer (p<0.01). Clay proportion also had a negative influence on pre-compression stress (p<0.01). Therefore, degree of soil compaction decrease, soil compressibility and load support capacity were increased with the increasing of recovery years. The conceivable reasons for increasing the soil compressibility and load support capacity were the decrease of soil bulk density, clay proportion and the increase of the content of organic matter due to the vegetation recovery.

從土壤力學角度出發，探究壓實過程中土壤性質的變化備受國內外學者關注[1-3]。通過土力學中固結試驗得到的土壤壓縮曲線，常用來表征土壤的壓實行為；由壓縮曲線進一步得到的土壤壓縮指數和先期固結壓力，則被廣泛應用于評價土壤的壓實敏感性和壓實風險[4]。由于土壤壓縮指數反映了土壤壓縮性的大小，所以壓縮性的大小與土壤耕性呈正相關[5]；先期固結壓力又反映了土壤面對外界壓力時的抵抗能力[6-7]；因此，土壤壓縮指數、先期固結壓力，可以反映出土壤承載能力的大小和耕性的優劣。

作為我國重要的商品糧生產基地，東北黑土區廣泛采用機械化耕作。機械化作業，一方面，推進了農業集約化進程，提高了農業生產效率；……