喀斯特山地土地利用方式对土壤团粒的影响——以重庆黔江为例
Land use effect on soil aggregates in the karst hilly areas—A case study in Qianjiang, Chongqing, China
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摘要: 土壤结构恶化是土壤侵蚀性退化的普遍现象和结果,在喀斯特地区表现尤为突出。本文以重庆黔江区为例,分析了四种不同的土地利用方式下,土壤团聚体的组成、稳定性及其影响因素。结果表明:研究区土壤颗粒组成主要集中在<0.05mm的范围内,土壤粘粒(<0.001mm)含量普遍较高;土壤经人为开垦利用转变为耕地后,表层土壤颗粒砂化明显;土地利用方式不同,风干团聚体含量相差不大,而水稳性团聚体组成和稳定性差异较大,＞5mm和＞1mm水稳性团聚体含量由大到小为:灌草坡＞林地＞退耕地＞耕地,＞0.25mm团聚体含量由大到小为:灌草坡＞退耕地＞林地＞耕地。灌草坡的水稳性团聚体含量最大,稳定性最强,耕地最差。有机质是影响水稳性团聚体的主要因素,因此,增加有机质的含量是恢复和改良喀斯特山地土壤结构状况的关键Abstract: Soil structure deterioration is a general phenomenon due to soil degradation by caused erosion especially in karst areas. The paper chooses Qianjiang as a case study and analyses the composition, stability of soil aggregates and its influencing factor under 4 different land use types. The result shows that most of the soil particles in the study area are smaller than0.05m m in diameter and the soil has a higher soil clay contents (greater than0.001m m in diameter). The topsoil particles will become coarsing or sandy obviously when the soil is tilled. The discrepancy of dry aggregate contents in the soil is not apparent, but the composition and water-stable aggregates are quite different with each other under different land use types. The contents of water-stable aggregate(>1m m and>5m m in diameter)decreases from shrub-grass land to woodland, abandoned land and cultivated land, while the contents of water-stable aggregate which have a diameter of big than 0.25mm decreases from shrub-grassland to abandoned land, woodland and cultivated land gradually. Shrub-grassland is the highest in content of stable-soil aggregate that their stability is highest; and the cultivated land is the lowest. The water-stable aggregates are mainly controlled by organic content; therefore, increasing the organic content is the key to modify the soil structure in karst hilly area.
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Key words:
- land use /
- soil structure /
- soil aggregate /
- karst mountain area /
- Qianjiang,Chongqing
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