干湿交替作用对西南地区黄壤团聚体稳定性的影响

为了探究我国西南地区干湿交替作用对土壤团聚体稳定性的影响,选取重庆缙云山典型黄壤为研究对象,在4个前期含水率(风干,10%,15%,20%)水平下,对4组不同粒级团聚体(1~2,2~3,3~5,5~7mm)分别进行7个不同干湿交替过程(1,2,3,5,7,10,15次)模拟。采用Le Bissonnais法,对干湿交替作用后的团聚体在不同破碎机制下的稳定性特征进行了探讨。结果表明:(1)快速湿润(FW)对团聚体稳定性的破坏程度最大,且与机械扰动(ST)和慢速湿润(SW)存在显著差异;(2)小粒径团聚体相较于大粒径团聚体稳定性更高;(3)干湿交替过程对团聚体存在明显的破坏作用,且在不同含水率变化范围下其破坏程度不同;(4)干湿交替作用主要通过影响团聚体破碎后2mm团聚体的百分比含量来影响团聚体的稳定性。该结果对于研究西南地区土壤侵蚀的发生机理具有一定的参考价值。

Influence of Dry-Wet Cycles on Aggregate Stability of Yellow Soil in Southwest China

To explore the influence of dry-wet cycles on soil aggregate stability in Southwest China,an experiment was conducted in the Jinyun mountain in Chongqing.The typical yellow soil in cultivated land was taken as the research object.With four groups of aggregates of different particle sizes (1-2,2-3,3-5,and 5-7 mm),seven dry-wet cycle processes (1,2,3,5,7,10,and 15 times) under four antecedent moisture levels (air dried,10％,15％,and 20％) were simulated.The stability features of soil aggregates after dry-wet cycles under different broken mechanisms were discussed with the Le Bissonnais method.The results showed that:(1) Fast wetting (FW) had the most serious damage on soil aggregate stability,and there was a significant difference between FW and the other two broken mechanisms (slow wetting (SW) and stirring (ST)).(2) Compared with large-size aggregates,the stability of small-size aggregates was higher.(3)The destructive effect of dry-wet cycles on aggregate stability was obvious,and the extent of the damage was different under different antecedent moisture levels.(4) The dry-wet cycle processes mainly affected the stability of aggregates by affecting the percentage of ＞2 mm aggregate fragmentation.These results had an important reference value for the study of soil erosion mechanisms in Southwest China.