Characteristics of alpine grassland soils and their change with pasture degradation in the eastern part of Qinghai-Tibet plateau
2008
Li, H.(Kagoshima Univ. (Japan)) | Hamazaki, T. | Nagatomo, Y. | Sakai, M.
Characteristics of alpine grassland soils and the relationships between level of pasture degradation and soil fertility in Zeku of the eastern part of Qinghai-Tibet plateau were investigated. The lightly degraded alpine pasture soils in Zeku were Haplic Phaeozems (Siltic, Calcaric) with a mollic horizon and the moderately and heavily degraded alpine pasture soils were Haplic Cambisols (Siltic, Calcaric) without a mollic horizon. Texture of Zeku soils was silt loam, derived from calcareous loess, and major clay minerals were mica, kaolin, vermiculite and chlorite. Organic carbon (OC) content, total nitrogen (TN) content and CEC of the soils ranged from 14.8 to 39.5 g/kg, from 1.4 to 4.0 g/kg and from 10.7 to 25.4 cmolc/kg in the surface horizons, respectively. Values of the soil pH (H2O) ranged from 7.6 to 8.8 and the soils contained 74 to 104 g/kg of calcium carbonates. However, they did not have any horizon of secondary carbonates accumulation. Moreover, accumulation of salts in the soils was not observed. Available nitrogen (AN) content ranged from 35 to 66 mg/kg and available phosphorus content ranged from 6 to 20 mg P2O5/kg in the surface horizons. The level of the both contents was very low. In the surface horizons, the OC, TN and AN content, and CEC of the soils decreased clearly with pasture degradation. On the contrary pH, base saturation percentage and calcium carbonates content increased with pasture degradation.
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