Spatial Variability Characteristics of Medium and Micro Nutrients in Wenshan Tobacco-growing Soil Based on GIS

• Pengfei LI, 
• Xiaofen YU, 
• Shuming YANG, 
• Yanmei ZHU, 
• Bingli ZOU, 
• Tianyang XU, 
• Ying WANG, 
• Xueli QIU