【目的】探讨东北黑土区耕地结构性状的退化程度与区域差异,为不同区域黑土地保护与退化耕地修复提供参考。【方法】以东北典型黑土区3个区域(丘陵漫岗、漫川漫岗、低山丘陵)未开垦草地和开垦60 a耕地为研究对象,利用干湿筛法和环刀法测定了土壤团聚体特征、土壤孔隙与持水特征以及土壤三相(固液气)结构特征并进行对比分析。【结果】开垦前丘陵漫岗和漫川漫岗区土壤团聚体机械稳定性、土壤团聚体水稳性、土壤孔隙度和持水量显著高于低山丘陵区,而广义土壤结构指数(值越大越适宜作物生长)显著低于低山丘陵区。长期(60 a)耕作后,土壤团聚体机械稳定性退化不明显,而土壤团聚体水稳性退化程度表现为低山丘陵>丘陵漫岗>漫川漫岗;土壤孔隙度和持水能力在丘陵漫岗和漫川漫岗退化严重,而在低山丘陵地区反而增加。表层0~10 cm土层固液气三相比例在丘陵漫岗和漫川漫岗区更加趋近理想三相结构,但低山丘陵区无显著变化;在3个区域20~40 cm土层均因固相比例增加导致土壤三相结构显著退化。【结论】东北典型黑土区开垦前土壤结构存在区域差异,丘陵漫岗和漫川漫岗区的土壤团聚体结构、孔隙结构和持水能力较优,低山丘陵区的土壤三相结构较优。农田土壤结构整体呈退化趋势,但退化程度存在区域差异,丘陵漫岗和漫川漫岗区土壤孔隙结构和三相结构退化较为严重,低山丘陵区土壤团聚体结构退化较为严重。

【Objective】This study aims to explore the degradation degree and area differences of soil structure in different areas across the typical black soil region, and to provide reference and basis for the protection of black soil and the restoration of degraded cultivated land. 【Method】 The characteristics of soil aggregates, soil porosity and water retention capacity, and soil three-phase structure of uncultivated grassland and farmland (cultivated for 60 years) were measured by dry-wet sieving and cutting ring method, and were comparatively analyzed in three areas (hill area, rolling hill area, low mountain area). 【Result】The results showed that the mechanical and water stability of aggregates, porosity, and water retention quality of soil were significantly better in the uncultivated hill area and rolling hill area than those in the low mountain area, while the generalized soil structure index was significantly lower in the low mountain area. The degradation of the mechanical stability of aggregates was not obvious after long-term cultivation (60 years), while the degradation of water stability of aggregates was in the order of low mountain area > hill area > rolling hill area. The total porosity and water retention capacity of the soil in the hill area and rolling hill area degraded seriously, while it showed an increased tendency in the low mountain area. The ratio of solid, liquid and gas phases of soil approached the ideal three-phase structure and was beneficial to crop growth in the 0-10 cm soil depth of the hill area and rolling hill area, but there was no significant change in the low mountain area. The increase in the solid phase proportion leads to the obvious degradation of the soil three-phase structure in the 20-40 cm soil depth of all three areas. 【Conclusion】The soil structure in uncultivated areas has regional differences in the typical black soil region. The hill area and rolling hill area had a superior aggregate structure, soil pore structure, and water retention capability, while the low mountain area had a superior soil three-phase structure. Farmlands in the three different areas across the typical black soil region showed a trend of degradation, with varying degrees of degradation among the areas. The soil pore structure and the three-phase structure of the hill area and rolling hill area degraded more seriously, while the aggregate structure of the low mountain area degraded more seriously.