Effects of Continuous Cropping Time on Soil Nutrient, Microbial Biomass, and Extracellular Enzyme Stoichiometry Characteristics of Tobacco-planting Soil

• Chuqi LIU, 
• Gaokun ZHAO, 
• Xiaopeng DENG, 
• Erdeng MA, 
• Junying LI, 
• Yi CHEN, 
• Yonglei JIANG, 
• Cong WANG