黄土沟壑区小流域不同地形下土壤微量元素分布特征

研究了黄土沟壑区小流域塬面、坡地、梯田和沟道土壤微量元素的剖面分布特征,以揭示不同地形条件下微量元素的有效性及地球化学特性.结果表明,不同土层土壤全量微量元素的变异系数均小于15%,为小变异土壤性质,有效态和吸附态铁和锰的变异系数均高于36%,为高度变异土壤性质;有效态和吸附态锌和铜属于中到高度变异.全量铁、锰和铜以沟道土壤较高,全锌、有效态和吸附态微量元素含量以塬面土壤较高.不同形态微量元素的剖面分布趋势取决于地形条件.不同地形下成土过程及不同地形条件所对应的土地利用方式造成了全量微量元素的差异,而土壤有机质含量的差异是不同地形条件下有效态和吸附态微量元素剖面分布特征不同的主要原因.

Distribution of Micronutrients in Soils as Affected by Landforms in a Loessial Gully Watershed

Landform is the most important environmental factor influencing the distribution of soil micronutrients in the Loess Plateau and the well understanding of the effects is an important prerequisite for the estimation of soil micronutrients' availability and geochemistry in the Loess Plateau. This study was therefore conducted in a watershed of the loessial gully region to reveal the effects of landforms on profile distribution of soil micronutrients. Soil samples from 37 profiles were collected and total, available and adsorbed iron, manganese, zinc and copper were determined. The results showed that total micronutrients varied slightly with covariance coefficients lower than 15%, while available and adsorbed micronutrients varied greatly in the studied area. Total contents of iron, manganese and copper were higher in gully bottom soils, while total zinc, available and adsorbed micronutrients were higher in plateau land soils compared with soils in other landforms. The soil-forming process and land use conditions in each landform are the major reasons for the differences in soil total micronutrients. Landform induced changes of soil organic matter is the major factor controlling profile distribution of available and adsorbed micronutrients.