西藏土壤有效锰含量及其影响因子分析

Status of Soil Available Manganese in Tibet and Its Affecting Factors

根据西藏土壤普查提供的18个供试土类162个剖面的有效锰和相关分析化验资料,运用数理统计方法,探讨土壤有效锰变化及其影响因子.西藏土壤表层和表下层有效锰含量分别平均约为46,17 mg/kg.各类土壤有效锰含量的变化趋势一般是：山地湿润森林型和旱生林灌型土壤较高（21-82 mg/kg）,其次是高山草甸型和河谷半水成型土壤（17-48 mg/kg）,最后是寒冻土和高山草原型土壤（7-23 mg/kg）.受多种因素的影响,尽管绝大多数土壤有效锰含量属于适宜或丰富水平之列,但变化比较大,因土壤类型和剖面层次而不同.土壤有效锰与有机质、粘粒含量呈显著正相关,与pH、碳酸钙含量呈极显著负相关,与阳离子交换量表现为极显著正相关.逐步线性回归分析显示,酸性土壤有机质等因子对有效锰影响的强弱程度顺序是：有机质,pH,粘粒甚小;石灰土：则是有机质最大,其次为pH,最后是碳酸钙、粘粒.

According to the analysis data of 162 soil profiles from 18 soil types in a soil survey in Tibet,soil available manganese（A-Mn） in the soil and its affecting factors were studied by mathematical statistics.The results showed that the average A-Mn of the surface soil and the subsurface soil was 46 mg/kg and 17mg/kg,respectively.Soil A-Mn varied with soil types.Mountain humid forest and drought forest-coppice soils had higher A-Mn,in the range of 21-82 mg/kg,while A-Mn in alpine meadow soil and valley semi-hydromorphic soil was in the range of 17-48 mg/kg.Frigid frozen soil and alpine steppe soil had the lowest A-Mn（7-23mg/kg）.The content of soil A-Mn showed large variance in different soil types and profile layers due to the effects of many factors,though the content A-Mn of major soil types was all at the medium or abundance level.Soil A-Mn was in highly significant positive correlation with organic matter and clay and in highly significant negative correlation with pH and CaCO3 content.The relation between soil A-Mn and CEC was apparent significant correlation.Stepwise linear regression analysis demonstrated that the influence of various factors on A-Mn appeared in the order of organic matter 〉pH,with a negligible influence from clay,for acid soil,and in the order of organic matter 〉pH 〉CaCO3≈clay for calcium soil.