石漠化区桑树地埂的土壤水分特征研究

Characteristics of Soil Moisture in Mulberry Terrace Embankments in Karst Rocky Desertification Area

石漠化区生态环境脆弱,坡耕地生物埂作为一种独特的农林复合措施,其对石漠化区坡耕地土壤水分分布和有效利用的影响作用明显。本文选取该区4种不同管理方式的桑树埂为研究对象,采用野外调查、理化分析及相关分析法,研究了坡耕地桑树地埂土壤水分垂直分布特征。结果表明:(1)不同生物埂土壤容重及孔隙状况均以天然林地和桑埂农地较好,桑埂撂荒地和桑埂自然生草地较低,有机质含量也以天然林地最大,桑埂农地次之(41.231g/kg),说明桑埂农地埂坎较其它生物埂蓄水能力强;(2)土壤水分入渗特性以自然生草埂最好,而桑埂清草地、桑埂撂荒地、桑埂农地均存在影响土壤水分入渗的限制土层,其土层分别位于20—30,10—20,30—40cm;(3)土壤持水性能以桑埂自然生草地最差,其中土壤通透库容以桑埂农地最大(1 088.2t/hm2),桑埂自然生草地最小(594.04t/hm2),而有效水库容也以桑埂自然生草地最小(331.68t/hm2),说明其易冲刷侵蚀且抗旱能力弱;(4)土壤容重、孔隙度、粘粒(<0.002mm)含量及有机质含量是影响土壤水分特性的主要因素,其与土壤饱和含水量、田间持水量、总库容和最大有效库容呈显著或极显著的相关关系。研究结果可为石漠化区土壤水分合理利用与季节性干旱调控及土壤保持提供科学依据。

In karst rocky desertification,the eco-environment is fragile.Terrace bio-embankment on sloping farmland is a special agro-forestry measure in this area,which has obvious influence on soil water distribution and its effective use in sloping farmland.In order to explore the vertical distribution characteristics of soil moisture in terrace embankments of mulberry on sloping farmland,terrace embankments of mulberry under 4different management modes were selected,and field investigations,physical and chemical laboratory analyses and correlation analysis methods were applied in this study.The results showed that：（1）Soil bulk density and soil porosity condition were better in natural forest land and farmland than in abandoned land and natural grassland,while soil organic matter content in natural forest land was the highest,followed by that in farmland（41.231g/kg）,which indicated that the farmland had the stronger water storage capability than other managing modes of mulberry terrace embankment.（2）Soil water infiltration characteristics of natural grassland was the greatest,while limiting layer of water transport existed in soils of weeded land,abandoned land and farmland,which located in 20—30cm,10—20cm and 30—40cm soil layers,respectively,leading to influence on soil water infiltration.（3）Soil water holding capacity of natural grassland was the worst,while the flood detention capacity of farmland was the greatest（1 088.2t/hm2）and that of natural grassland was the poorest（594.04t/hm2）.The effective water storage capacity of natural grassland was also the poorest（331.68t/hm2）,indicating that the natural grassland was prone to erosion and had low drought resistance.（4）Themain influencing factors on soil moisture characteristics were soil bulk density,soil porosity,the content of clay（〈0.002mm）and soil organic matter content,which were significantly or highly significantly correlated with soil saturated water content,field moisture capacity,total reservoir storage and maximal effective storage.These results could provide scientific basis for reasonable utilization of soil moisture,regulation of seasonal drought and soil conservation in rocky desertification areas.