High crop yield and soil fertility are all important parts of sustainable agricultural development, while maintaining or improving soil fertility assures higher yield and better quality of crop. Soil fertility is the basic property of soil, and also reflects soil physical, chemical and biological properties. The sudangrass(Sorghum sudanense) and ryegrass(Lolium multiflorum L.) rotation was a new type and more intensive cropping system in the south of China, which developed very fast in recent years, and gro...