不同草地类型土壤有效态微量元素含量特征

Study on the Contents of Available Trace Elements in Different Grassland Soils on the Western Slope of the Helan Mountain

以贺兰山西坡不同草地类型土壤为对象，研究了土壤中微量元素Fe，Mn，Zn，Cu有效态含量特征及土壤有机碳、pH值、黏粉粒含量与气候因素之间的相互关系。结果表明：土壤有效态Fe，Mn，Zn的含量随着海拔的降低而逐渐降低，有效态Cu含量的积累顺序为：山地草原〉荒漠化草原〉高山草甸〉草原化荒漠。4种元素在各种草地类型的积累量变化为：高山草甸Fe〉Mn〉Zn和Cu；山地草原和荒漠化草原Fe〉Mn〉Cu〉Zn，草原化荒漠土壤中Fe和Mn含量差异不大，并大于Zn和Cu。土壤有效态Fe，Mn，Zn的含量与年均降水量、土壤有机碳、〈0．05mm黏粉粒含量都呈显著正相关，而与年均温度和土壤pH值呈显著负相关。土壤有效态Cu含量与年降水量、年均温度、土壤有机碳含量和〈0．05mm黏粉粒含量基本呈二次多项式，而与土壤pH相关性不显著。影响土壤有效态Fe和Mn含量的关键因素，0～20cm土层为有机碳、年降水量和年均温，而20～40cm土层土壤有机碳是其最重要的影响因素。0～20cm土层土壤有效态Zn主要受土壤pH、黏粉粒含量和年降水量的影响。

This paper analyzes the correlations between the contents of available trace elements including iron （Fe） , manganese （Mn） , zinc （Zn） and copper （Cu） in different grassland soils with different elevations on the western slope of the Helan Mountain in Alxa, Inner Mongolia. The factors affecting the contents of available trace element distribution, such as annual precipitation, temperature, soil organic carbon, content of clay with granule diameter 〈0.05 mm and soil pH value, are also analyzed. The results reveal that the contents of available Fe, Mn, and Zn in soil reduce gradually with the decrease of elevation; the accumulation of available Cu content is in a sequence mountain steppe 〉 desert steppe 〉 alpine meadow 〉 steppe desert. The accumulation of these elements is inasequence of Fe〉Mn〉Zn〉Cu in alpine meadow soil, and a sequence of Fe〉Mn〉Cu〉Zn in mountainous steppe and desert steppe soils. In the steppe desert, the difference between the contents of Fe and Mn is not so high but higher than that between Zn and Cu. There is a significant positive correlation between the conof soil organic carbon and content of clay with granule diameter 〈 0.05 mm, but a significant negative correlation between them and annual temperature and soil pH value. The correlation between the content of available Cu and the precipitation, annual temperature, content of soil organic carbon and content of lay with granule diameter 〈 0.05 mm can be expressed by a quadratic polynomial, but the correlation between the content of available Cu and the soil pH value is not significant. The key factor affecting the contents of Fe and Mn in soil layer of 0 - 20 cm in depth is organic carbon, especially in soil layer of 20 -40 cm. The content of available Zn in soil layer of 0 -20 cm is mainly affected by soil pH value, content of clay with granule diameter 〈0.05 mm and annual precipitation.