冻融循环作用对黑土团聚体破碎机制的影响

为探究冻融循环作用对黑土团聚体抵抗不同破坏作用能力的影响,以黑龙江省典型黑土耕作层土壤为研究对象,通过LB法的3种不同破碎处理,分析冻融循环次数、初始含水量对不同初始粒级土壤团聚体稳定性的作用机制。结果表明:冻融循环作用对1～2,2～3,3～5 mm不同粒级团聚体稳定性有显著影响(P0.05),其稳定性均呈现为湿润振荡(WS)慢速湿润(SW)快速湿润(FW),快速湿润(FW)处理对黑土团聚体稳定性的破坏作用最大,而慢速湿润(SW)和湿润振荡(WS)破坏作用较小。同时,初始含水量和冻融循环次数对3种不同粒级团聚体的快速湿润平均重量直径(MWD_(FW))、慢速湿润平均重量直径(MWD_(SW))、湿润振荡平均重量直径(MWD_(WS))均具有极显著影响(P0.01)。随着冻融循环交替次数的增加,0.2 mm的大团聚体破碎而小团聚体(0.2 mm)含量增加。初始含水量对于2～3,3～5 mm粒级团聚体具有破坏作用,而对1～2 mm粒级团聚体有助于改良团聚体结构,增大团聚体稳定性。

Effect of Freeze-thaw Cycle on the Fragmentation Mechanism of Black Soil Aggregates

In order to explore the effect of freeze-thaw cycle on the ability of black soil aggregate to resist the influence of different damage. the typical black soil of Heilongjiang province was taken as the research object. and the effects of freeze-thaw cycles and the initial moisture content on stability of soil aggregate with different initial size were analyzed through three different crushing processes of LB method. The results showed that the freeze-thaw cycles had significant effect on the stability of aggregates with different size of 1~2, 2~3 and 3~5 mm (P<0.05). The stability of aggregates followed the order of wetting oscillation (WS) > slow wetting (SW) > fast wetting (FW). FW treatment had the greatest damage to the stability of black soil aggregates, while the SW treatment and WS treatment had less damage. At the same time, the initial water content and the number of freeze-thaw cycle had extremely significant influence on the MWD_FW, MWD_SW and MWD_WS of three different sizes aggregates (P<0.01). With the increasing of the number of freeze-thaw cycle, the large aggregate of >0.2 mm was broken and the content of the small aggregate (<0.2 mm) increased. The initial water content had a destructive effect on 2~3 and 3~5 mm aggregates, while for 1~2 mm aggregates, it was helpful to improve the structure and increase the stability of aggregates.