中文摘要：

2007-2012年在陕西合阳连作玉米田进行保护性轮耕与施肥长期定位试验，设置免耕／深松（NT-ST）、深松／翻耕（ST-CT）和翻耕／免耕（CT-NT）3种隔年交替轮耕处理和连续免耕（NT-NT）、连续深松（ST—ST）、连续翻耕（CT—CT）3种连耕处理及平衡施肥、低肥和常规施肥3种施肥处理，分析了0～40em土壤团聚体分布、平均质量直径（MWD）、几何平均直径（GMD）、分形维数（D）及0～60cm土壤有机碳（SOC）含量．结果表明：随着耕作强度的增加，土壤团聚体总含量减小，稳定性降低，有机碳损失增大；连续免耕和轮耕增大了土壤团聚体MWD和GMD，减小分形维数，增加了粒径大于0．25mm团聚体（R0．2，）和SOC含量．在相同施肥处理下，团聚体Rn25表现为NT—NT〉NT—ST〉NT—CT〉ST—ST〉CT—ST〉CT—CT；在相同耕作方式下，平衡施肥和低肥处理下土壤团聚体比常规施肥更稳定。通过对土壤团聚体分形维数进行数学拟合，干筛法和湿筛法所测土壤团聚体的分形维数分别为2．247—2．681和2．897—2．976．0～30cm土层土壤团聚体分形维数均表现为连续免耕和轮耕显著低于连续翻耕（CT—CT），随土层加深分形维数增大，在40cm处趋于稳定．施肥对不同土层有机碳含量的影响差异显著（P〈0．05），随土层加深有机碳含量呈递减趋势，平衡施肥处理下有机碳积累量较常规施肥增加了6．9％．土壤有机碳含量随团聚体粒径的增大而增加，O．25～2mm粒径土壤团聚体含量对有机碳积累的影响达到显著水平（P〈0．01），确定系数R^2为0．848．

英文摘要：

A field experiment on effects of tillage rotation and fertilization on corn continuous cropping-practiced lands was carried out in Heyang of Shaanxi in 2007-2012. The tillage types included annual rotation of no-tillage and subsoiling （NT-ST）, subsoiling and conventional tillage （ST-CT）, or conventional tillage and no-tillage （ CT-NT）, and yearly practice of no tillage （ NT-NT）, subsoi- ling （ST-ST） or conventional tillage （CT-CT）. The fertilization treatments included balanced ferti- lization, low-rate fertilization and conventional fertilization, which were separately practiced against the different tillage types. The experiment investigated compositions, mean mass diameters （MWD）, geometrical mean diameters （GMD） and fraction dimension numbers （D） of soil aggre- gates in 0-40 cm soil and contents of organic carbon in 0-60 cm soil. The results indicated that： 1 ） The increased tillage intensity caused the reduced mechanical stability and content of soil aggre- gates and increased soil organic carbon loss. No-tillage or tillage rotation increased the MWD, GMD and contents of soil organic carbon and soil aggregates with diameters of more than 0.25 mm, but decreased D. Under the same fertilization treatment, the contents of soil aggregates with diameters of more than 0.25 mm were ranked in the order of NT-NT〉NT-ST〉NT-CT〉ST-ST〉CT-ST〉CT-CT, and under the same tillage rotations, the soil aggregates were more stable with the balanced or lowrate fertilization than with the conventional fertilization. 2） Mathematical fraetal dimension fitting of soil aggregates indicated that the fractal dimension numbers of soil aggregates ranged within 2. 247- 2. 681 by dry sieving and 2. 897-2. 976 by wet sieving. In 0-30 cm soil, the fractal dimension numbers of soil aggregates were significantly lower under no-tillage or tillage rotation than under conventional tillage, and in 0-40 cm soil, the fractal dimensions of soil aggregates increased with soil depth, and tended to stabiliz