中文摘要：

以大豆（S）、玉米（M）、小麦（W）和草本植物（GL）的根际土和裸地（BL）作为处理,研究了不同植物根际土壤团聚体组成、稳定性以及团聚体结合碳的分布。结果表明,草地以水稳性大团聚体（〉0.25 mm）占绝对优势,比例达85.9%;与草地相比,农田三种作物处理显著降低了大团聚体的比例,质量分数为68.7%;裸地大团聚体比例（55.7%）最小,尤其是〉2 mm的团聚体仅占3.5%。团聚体水稳定性草地最高,裸地团聚体水稳定性最差,农田三种作物处理居中。玉米、小麦和大豆三种作物根际土壤团聚体在组成上并无显著差异,而玉米根际土壤团聚体稳定性显著高于小麦和大豆。草地团聚体结合碳量最高,为36.0g kg-1土,比农田（平均33.9 g kg-1土）和裸地分别高出5.8%和16.7%。大团聚体（〉0.25 mm）是有机碳存储的主要部分,因此保护和维持这部分团聚体的数量和稳定性对于抵押CO2排放和土壤肥力的可持续发展具有重要意义。

英文摘要：

Stable aggregates,resistant to the stresses induced by wetting,are important for maintaining agricultural productivity and protecting soil organic carbon（SOC）.This study was undertaken to assess aggregate stability and determine content of aggregate-associated organic C under bareland（BL） and in rhizosphere soil under grassland（GL） and cropland cropped to maize（M）,soybean（S） and wheat（W）.Results indicated that the percentage of water-stable aggregates 0.25 mm（WSA0.25mm） was the highest in grass rhizosphere,at 85.9% and that was smaller in wheat,soybean or maize rhizosphere,accounting for 68.7%.Bareland has the lowest percentage,at 55.7%.Aggregate stability decreased in the order GL M W S BL.No differences in percentage of different size fraction of water-stable aggregates were found in rhizosphere of wheat,soybean and maize.The deterioration rate of aggregates 0.25 mm（ADR0.25mm） showed that maize cropping increased soil aggregate stability relative to wheat and soybean cropping.The total content of associated-aggregate organic C in grass rhizosphere was 36.0 g kg-1 soil,which was 5.8% and 16.7% higher respectively than that under bareland and cropland.Macroaggregates（ 0.25 mm） share the largest part of C storage,so promoting the formation and stability of this fraction has important significance for sequestering C dioxide and cultivating the soil in a sustainable matter.