Abstract: In order to understand the composition and stability of soil aggregates of Desert Highway shelterbelt in Tarim,soils of 0-20 cm in 5 different planting age’s shelterbelt were analyzed through field sampling and laboratory analysis. Dry sieving method and wet sieving method were used in this study. The results showed that: ① Under the condition of dry sieve,the content of >0.25 mm air drying soil aggregates is between 33.35-280.38 g·kg^-1 in different layers,and the >5 mm aggregate is predominant in different layers,about 41.56%-70.09%; the 5-2 mm aggregate comes second,about 6.58%-34.88%,the 1-0.5 mm aggregate content was the lowest,only 1.66%-5.46%. Under the condition of wet sieve,the content of >0.25 mm water-stable aggregates is between 0.21-72.54 g·kg^-1 in different layers,and the change of soil aggregates decreased with the decreasing of particle size for all planting age’s shelterbelt. ② With the increasing of shelterbelt planting years,the content of air drying soil aggregates increased from 69.94 g·kg^-1 to 159.88 g·kg^-1,and the content of water-stable aggregates increased from 0.41g·kg^-1 to 60.84 g·kg^-1 in 0-20 cm soil layer,while there is no aggregate formation in quicksand. Shelterbelt plantation promoted the formation of aeolian sandy soil. ③ With the increasing of planting years,the content of >0.25 mm air drying soil aggregates (SDA_{>0.25 mm}) and water-stable aggregates (WSA_{>025 mm}),mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates increased,and the correlation between these parameters are significant (P<0.01). ④ The content of >2 mm air drying soil aggregates can be used to characterize the mechanical stability of soil aggregates in the shelterbelt soil; and the content of >1 mm water-stable aggregates can be used to characterize the water-stability of soil aggregates in the shelterbelt soil. Planting shelterbelt on aeolian sandy soil along Tarim Desert Highway could increase the formation of soil aggregates,promote the aggregates to be well-distributed and improve the mechanical stability and water-stability of soil aggregates,and accelerate the soil forming process.

Key words: shelterbelt, soil aggregates, composition, stability, Tarim Desert highway