西藏土壤钾素状况及其影响因素分析

根据西藏 16个土类 138个土壤剖面 4 6 5层土样的分析资料 ,讨论土壤的全钾和速效钾状况及其影响因素。结果表明 :西藏土壤全钾较丰富 ,主要由于成土母质中钾含量较高 ,其主要原因是母质钾的风化淋溶程度低。由于土壤有机质对矿物钾的“稀释效应” ,致使一般土壤 (表层 )全钾低于母质全钾 ;同时在富含钙质的碱性土中 ,CaCO3的聚积对全钾也有一定的“稀释效应”。西藏绝大部分土壤的速效钾处于高供钾水平 ,其含量主要决定于土壤CEC ,进而又主要决定于有机质含量 ,在少部分土壤中也与粘粒含量有关。此外在富含有机质的酸性土中 ,速效钾含量还受盐基饱和度的影响。

Status of Soil Potassium and Its Affecting Factors in Tibet

According to the analysis data of 465 soil samples from 138 soils profiles of 16 soils types, soil potassium and its affecting factors were studied. The contents of soil total potassium (STK) are 17.7～23.4、g/kg in surface horizon and 20.3～27.6、g/kg in C horizon which are abundant. Parent material which has lower weathering intensity and plentiful potassium is the main effecting factor of STK. In general, organic matter in surface layer makes "dilution effect" of the mineral potassium (r=-0.559 **), so that the STK of surface horizon is lower than that in parent material horizon. At the same time the accumulative CaCO 3 makes "dilution effect" of the mineral potassium in alkaline soils. Available potassium contents in most soils types are higher than 100、mg/kg. Correlation coefficient of the soil available potassium (SAK) with soil cation exchange capacity (CEC) with soil organic matter in the soils is the significant (0.547 ** and 0.515 **), respectively. The relationship of SAK with soil clay is significant only in several soil types. Moreover, in acid soil the SAK has higher coefficient with base saturation (BS%) than CEC.