| Phosphorus is a key nutrient element that determines soil fertility and affects the growth of vegetation Selenium is necessary nutrient element in the human diet.Insufficient or excessive intake of selenium will endanger human health.In this dissertation,the Dabie Mountain in west Anhui Province was taken as the research area.The aims of this study were:?1?to explore the current level of phosphorus and selenium;?2?to reveal the spatial variations of soil total phosphorus and soil total selenium?3?to investigate the relationships between soil nutrient elements and pertinent environmental factors;A total of 774 top soil samples?0-20 cm?and 220 deep soil samples?150-180cm?were sampled.The environmental conditions of each sampling site were meanwhile recorded,including latitude,longitude,elevation,slope gradient,slope aspect,soil type and land use type.All the soil samples were taken to the laboratory for measurements of soil total phosphorus,soil total selenium,soil organic carbon,soil pH and other physical and chemical properties.The main results were listed as follows:?1?The content of phosphorus ranged from 267.1 to 547.3 mg·kg-1,the mean value of phosphorus was 349.4 mg·kg-1.The coefficient of variation was 35.8%.The content of phosphorus showed a distinct spatial distribution,which was gradually increased from northeast to southwest in the study area.?2?The percentage of phosphorus deficiency accounted for 85.27%in the study area;The soil microelements are overall in a moderate level except copper with slight lack,The content of selenium were lower than the average value of the other soils in China,as a whole,the result showed that the content of selenium were at medium to lack level in the study area.?3?The distributions of phosphorus in different soil parent material,soil type,topography,land use were as follows:sandy shale<siltstone<gneiss<granite<amphibolite;purple soil<paddy soil<coarse soil<yellow brown soil<brown soil;hills<low mountains<middle mountains;rice fields<tea fields<woodland<dry land.The main controlled factors of phosphorus in the study area were parent material,landform type,altitude,slope,land use type,soil type,oxide of iron and aluminum and clay content.?4?The content of selenium varied from 0.11 to 0.54 mg·kg-1,with the mean value of 0.22 mg·kg-1.The spatial distribution of selenium showed the potential deficient to moderate level from the northeast to the southwest in study area.Under the conditions of different soil parent materials,the content of selenium in the top soil was controlled by the deep soil.The distribution of selenium under different soil types and land use types was:brown soil<coarse bone soil>paddy soil<yellow brown soil>purple soil;dry land<paddy field<tea land>woodland.Selenium showed a good correlation with sulphur and carbon,and the correlation of clay content and soil pH to selenium was weak,and it was mainly influenced by the soil parent material and the content of soil organic matter. |
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