Spatial Variation Characteristics And Zoning Management Of Cultivated Soil Trace Elements In Northwest China

Northwest China is an important grain-producing area and reserve arable land resource distribution area in China.There are problems such as infertile soil,low level of nutrient input and poor quality of arable land,especially the lack of more systematical studies on soil micronutrients.Based on the macroscopic spatial scale,this study used the attribute data of soil survey and sampling,and applied classical statistics,geostatistics,Kriging interpolation method,least squares method and other methods to study the spatial variation and distribution characteristics of available Cu,Zn,Fe and Mn in soil trace elements around the unclear spatial characteristics of the abundance and deficiency distribution of trace elements in cultivated land in Northwest China.The spatial differentiation characteristics and influence effects of trace elements in cultivated land were analyzed,and the management zoning scheme of trace elements in cultivated land was discussed.The aim was to provide reference for improving the quality of cultivated land and promoting sustainable development.The research conclusions are as follows:（1）The average contents of available Cu,Zn,Fe and Mn in cultivated soil in Northwest China were 1.50 mg kg^-1,0.86 mg kg^-1,10.69 mg kg^-1 and 9.57 mg kg^-1,respectively,with moderate variability.On the whole,the average content level of available Fe is at a relatively rich（upper middle）level,and available Cu,Zn and Mn are at a general（middle）level;（2）The coefficient of variation of available Cu,Zn,Fe and Mn in cultivated soil in Northwest China was between 36.3%and 49.9%,which showed a moderate variation level.The spatial variation characteristics depended on the combined effect of random factors and structural factors.（3）The content distribution area of effective Cu,Zn,Fe and Mn in the northwest region accounts for the largest proportion of the general（medium）level,forming the spatial distribution characteristics of a small polar horizontal distribution area and a wide general（medium）level distribution area.The distribution of effective Cu and Fe is relatively consistent.The low value areas are concentrated in Qinghai Province,Gansu Province,Ningxia Hui Autonomous Region and northern Shaanxi,and decrease from west to east.The distribution of effective Zn is generally at the lower middle level,and Qinghai Province and Ningxia Hui Autonomous Region are particularly low.Gansu Province is high in the northwest and low in the southeast.The high value area of Xinjiang Uygur Autonomous Region is scattered.Shaanxi Province is characterized by low in the middle and high in the north and south,and the distribution of available Mn is generally at the lower middle level.（4）The content of trace elements in cultivated soil was significantly correlated with soil pH and fertilizer（N/P₂O₅/K₂O）.The average content level of available Fe in the cultivated soil of northwest China was relatively rich（above the medium level）,and the average content level of available Cu,Zn and Mn was general（medium）.In agricultural production,management measures should be formulated in combination with random factors and structural factors,and zoning management should be carried out according to the demand level of different effective trace elements,and the pertinence of trace element fertilizer application should be strengthened.