Change of nutrients and botanical composition of mixed Lolium perenne ╋Trifolium repens grasslands under long-term grazing and mowing utilizations

• Hong SUN, 
• Ying-wen YU, 
• Xiang-li MA, 
• Hong-mei ZHANG, 
• Xiao-ming MOU, 
• Jia-fa LIAO, 
• Fu-jiang HOU