In order to study the distribution characteristics and stability of long-term cultivated soil aggregates in Zhoukou City, Henan Province, four different cycles of

dry-wet alternation were designed, which were 0, 1, 3 and 5 times, respectively. The aggregate content, mean weight diameter (MWD) and geometric mean diameter (GMD) of different soil layers were measured by dry sieving method and wet sieving method. The results showed that, under dry sieving condition, the content of  aggregate >0.25 mm was significantly reduced by 5 times dry-wet cycles, the MWD value of each soil layer was significantly increased by dry-wet cycles, and the GMD value of each soil layer was significantly increased by 1 and 3 times dry-wet cycles. Under wet sieving condition, dry-wet cycles had different effects on the content of  aggregate >0.25 mm in different soil layers, and the MWD and GMD values of each soil layer were significantly reduced by once dry-wet cycle. The MWD values of 40—60  and 60—80 cm soil layers were significantly increased by 3 and 5 times dry-wet cycles. Three dry-wet cycles significantly increased the GMD value of 80—100 cm soil layer, and 5 times dry-wet cycles significantly decreased the GMD value of 0—20, 20—40, 40—60 and 80—100 cm soil layer. The percentage of aggregate destruction in once dry-wet cycle treatment was significantly higher than that in other treatments. To sum up, the dry-wet cycle treatments affected the status of soil aggregates, and mainly showed that the proportion of soil aggregates >0.25 mm was decreased. The present research provided theoretical reference for the stability maintaining of farmland soil structure in Huang-Huai area.

为了研究河南省周口市长期耕作土壤团聚体的分布特征和稳定性，设计不同循环的干湿交替，分别为0、1、3和5次。采用干筛法和湿筛法测定不同土层各粒级土壤团聚体含量、平均重量直径（mean weight diameter，MWD）和几何平均直径（geometric mean diameter，GMD）。结果表明，干筛条件下，5次干湿交替显著降低>0.25 mm团聚体含量，干湿交替显著增加各土层MWD值，且1和3次干湿交替显著增加各土层GMD值。湿筛条件下，干湿交替在不同土层对>0.25 mm团聚体含量影响不同，1次干湿交替显著降低各土层的MWD和GMD值；3和5次干湿交替显著增加40—60和60—80 cm土层MWD值；3次干湿交替显著增加80—100 cm土层GMD值，5次干湿交替显著降低0—20、20—40、40—60和80—100 cm土层的GMD值。1次干湿交替的团聚体破坏率显著高于其他处理。综上，干湿交替影响了土壤团聚体状况，且主要表现为>0.25 mm团聚体比例下降。结果对于黄淮地区农田土壤结构稳定性的维持提供一定理论参考价值。