摘 要 ：土壤团聚体是土壤的重要组成部分，其大小分布影响土壤的功能。本文利用22年土长期定位试验，研究不同土壤管理措施和不同施肥对土壤机械稳定性和水稳性团聚体的分布及其稳定性的影响。土壤管理措施包括裸地休闲、 撂荒和小麦/玉米轮作体系，其中小麦/玉米轮作体系中有9种施肥处理，分别为不施肥（CK），化肥氮（N）、 磷（P）和钾（K）不同配施5个处理（N、 NP、 NK、 PK、 NPK），秸秆还田与化肥配合（SNPK），有机肥与化肥配施2个处理（M1NPK、 M2NPK）。结果表明，不同管理措施显著影响表层（0—10 cm）和亚表层（10—20 cm）土壤的机械稳定性和水稳性团聚体的分布。与作物体系比较，长期休闲可显著增加机械稳定性微团聚体（<0.25 mm）的含量，对水稳性团聚体的含量和分布没有显著影响。而长期撂荒显著增加了大于2 mm 的团聚体含量及团聚体的稳定性。长期不同施肥显著影响 0—30 cm 土层的机械稳定性和水稳性团聚体的分布，总趋势为施肥比不施肥处理降低了>1 mm的团聚体含量，增加了0.25~1 mm的团聚体含量，但对土壤团聚体的稳定性没有显著影响。因此，土撂荒22年后显著增加了土壤团聚体的稳定性，而种植作物和不同施肥处理对土壤团聚体的稳定性影响甚微。
Abstract: Soil aggregate is a main component of soil, and its size distribution has an important effect on soil function. This study investigated effects of soil management practices on distribution of dry aggregates and water-stable aggregates based on a 22-year long-term experiment on Lou soil in Guanzhong Plain, Shaanxi province, China. The soil management practices were cropland abandonment (Set aside), bare fallow without vegetation (Fallow) and a wheat-maize cropping system (Cropping). The Cropping was combined with the following nutrient management treatments: control (CK, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PK), NP, NPK and straw plus NPK (SNPK) and two levels of manure plus NPK (M1NPK and M2NPK). The soil management practices have significantly effects on the distribution of dry aggregates and water stable aggregates in the surface and subsurface soil layers (0-10 and 10-20 cm). Compared with the Cropping, the fallow treatment increases the proportion of dry microaggregates (<0.25 mm), but has no significant effects on distribution of water-stable aggregates, and the Set aside treatment increases the proportion of macroaggregates (larger than 2 mm in size) and aggregate stability. The distributions of dry aggregates and water stable aggregates are significantly impacted by the fertilization in all soil depths under the Cropping. Generally, the proportions of aggregates in sizes >1 mm under the fertilization are lower than those of no fertilization, and the proportions of aggregates in sizes of 0.25-0.5 mm and 0.5-1 mm in the treatments which received both N and P are higher than that of the control. It is concluded that the abandonment of cropland after 22-year significantly improves aggregate stability, while the long-term fertilization practices significantly influence the distribution of soil aggregates and have not significant effects on the aggregate stability under the cropping system in Lou soil.