Characteristics of nitrogen content between rhizosphere and bulk soil of Amorpha fruticosa with different plant ages in southern rdge of Mu Us Desert

• Yuanyuan ZHOU, 
• Mingxin DU, 
• Xiangrui ZHOU, 
• Zhiyu ZHOU, 
• Xin LU, 
• Xiaohui TAO, 
• Ping ZHAO, 
• Jinhui LI, 
• Qian JIN