我国缺乏微量元素的土壤及其区域分布

微量元素指土壤中含量很低的化学元素。有的微量元素是植物正常生长和生活所不可缺少的营养元素。土壤是微量元素的主要给源。

GEOGRAPHICAL DISTRIBUTION OF TRACE ELEMENTSDEFICIENT SOILS IN CHINA

The geographical distribution of soils deficient in trace elements including boron, molybdenum, manganese, zinc and copper in China has been studied. Five nationwide maps of the content of these elements are compiled based on the soil map of China on the scale of 1:10,000,000. These maps show that in the country there are not only the soils which result in trace elements deficiency of plants, but also the soils which result in the imbalance of trace elements of plants, all these soils will affect the crop yield.There are large areas of boron-deficient soils in the eastern and southern China. The content of laoron in soils varies with the soils types and parent materials. Laterite, lateritic soil and red earth derived from granite and other igneous rocks, gneiss and sandstone are lower in total and available boron. Symptoms of boron-deficiency of crops may be observed on these soils: In the cases of severe boron-deficiency, even complete failure of rape yield was found. Many molybdenum-deficient soils are distributed in China including two main Mo-deficient soil regions. One of these is the region of loessial soils and lightcolored meadow soils derived from alluvium of the Yellow River, in which the contends of total and available molybdenum are low. The other one is the region of laterite,lateritic soils, red earth and yellow earth, in which the content of total molybdenum is high and content of available molybdenum is low. Good response of leguminoues crops to molybdenum fertilizers has been found on these soils.