岩溶坡地不同利用类型土壤入渗性能及其影响因素

Soil infiltration capacity and its influencing factors of different land use types in Karst slope

为了探讨岩溶坡地不同土地利用类型土壤入渗性能差异及其影响因素,该文利用环刀法测定了不同利用类型石灰岩土壤的入渗过程曲线,并分析了孔隙状况、颗粒组成和土壤结构等对入渗的影响。结果表明:土地利用类型对岩溶坡地土壤入渗性能影响较大,初始入渗速率和稳定入渗速率均表现为灌丛>果园>草地>旱地。灌丛地表下层(>15～30cm)平均稳定入渗速率8.11mm/min,最小值4.22mm/min;旱地地表下层平均稳定入渗速率0.46mm/min,最小值仅0.13mm/min。旱地表层以下存在显著的入渗阻滞层。岩溶坡地土壤入渗性能与有机质、水稳性团聚体和孔隙度有显著相关性。非毛管孔隙在入渗初期的作用大于后期,>0.25mm水稳性团聚体含量是影响稳定入渗速率的重要因素。该文为进一步研究岩溶坡地旱涝灾害、水土保持和水资源开发利用等提供了理论依据。

In order to ascertain soil infiltration capability and analyze its influencing factors in Karst region,this paper studied soil infiltration curves and their characteristics of four land use patterns in a Karst hill by using infiltration ring.Soil bulk density,porosity,soil particle-size distribution,water-stable aggregates and organic matter were also measured.The study indicated that,soil infiltration rates and permeability in surface layers of the four land use types were similar,but big difference existed in sub-layers between dry lands and other land use patterns.Land utilization was an important factor which should be responsible for the variation of infiltrability.Stable infiltration rates in soils,under natural conditions,were very high;cultivation and deforestation appeared to increase soil bulk density,while also reducing organic matter,water-stable aggregates and infiltration rates.Initial and stable infiltration rates changed in the same order：shrub landorchardgrass landdry land.Mean value of stable infiltration rates of sub-layers（15-30 cm）in shrub profiles was 8.11 mm/min,which was much higher than that of dry land（0.46 mm/min）.The lowest value of stable infiltration rates in shrub soils was 4.22 mm/min that was thirty three times of dry lands（0.13 mm/min）.Obstacle layers associated with low infiltration rates existed in sub-layers of dry land profiles.There were significant positive correlations between permeability and organic matter,soil porosity and water-stable aggregates.Water-stable aggregates and soil organic matter were the principal influential factors which affect infiltrability in Karst slope.This research provides theoretical basis of exploring and utilizing Karst water resource,soil and water resource conservation.