Effects of Different Soil Improvement Organic Materials on Soil Nutrient Supply in Tobacco Fields and Carbon and Nitrogen Metabolism of Tobacco Plants

• LI Xinlei, 
• XIE Yiyan, 
• SHAN Qu, 
• ZHANG Yubiao, 
• ZHAO Zhengxiong, 
• YANG Dehai, 
• OUYANG Chengren