喀斯特不同土地利用类型裂隙土壤有机碳及磷素赋存特征

以喀斯特石漠化区不同土地利用类型裂隙土壤为研究对象,运用野外调查和实验室内分析相结合方法,探索其有机碳和磷素含量变化及其赋存特征,以期为喀斯特地区开展石漠化治理和植被恢复提供理论依据。结果表明：4种土地利用类型裂隙土层土壤有机碳赋存含量变化范围为16.067-39.436 g/kg,总体呈现出随土层深度增加而降低的变化趋势;土壤全磷、有效磷赋存含量变化范围分别为0.093-0.274 g/kg、3.836-8.025 mg/kg,整体上在裂隙表层显著高于其他土层,具有上层高下层低的特点;同时,土壤有机碳和磷素总体上属于中度变异。乔木林地和灌丛地的C/P总体上表现出随土层的加深而减小的趋势,而草地和撂荒地先减小后增加,土壤C/P在各土地利用类型裂隙土层变化范围为86.499-268.343,磷的有效性较低;随土层深度的增加,各土地利用类型裂隙土壤有机碳、全磷和有效磷含量逐渐在减少,有机碳对土壤碳磷比、有效磷含量变化有一定影响。

Occurrence characteristics of organic carbon and phosphorus in fissured soil under different land use types in Karst area

The goal of this study was to determine the changes in soil organic carbon (SOC) and phosphorus (P) content and their occurrence characteristics, to provide the theoretical basis for rocky desertification control and vegetation restoration in the karst area. Adopting field investigation and indoor analysis methods, different land use types of fissured soil in karst rocky desertification area were taken as the research object. The results indicated that the variation range of soil organic carbon (SOC) content in four types of land use was 16.067-39.436 g/kg, showing a trend of decreasing with the increase of soil layer depth. The total phosphorus (TP) and available phosphorus (AP) contents in the soil varied from 0.093-0.274 g/kg and 3.836-8.025 mg/kg, respectively, which were significantly higher in the fissure surface layer than in other soil layers in the whole, with the characteristics of higher in the upper layer and lower in the lower layer. Besides, soil organic carbon (SOC), total phosphorus (TP), and available phosphorus (AP) were generally moderately variable. Soil C/P ranged from 86.499 to 268.343 in the fissured soil of the four land-use types, which indicated that the availability of P was low, and C/P of arboreal land and shrubland decreased with the deepening of the soil layer, while that of grassland and abandoned land decreased first and then increased. With the increase of soil depth, the content of organic carbon (SOC), total phosphorus (TP), and available phosphorus (AP) in fissured soil decreased gradually and soil organic carbon (SOC) had affected the changes of C/P and available phosphorus (AP) content.