Cover crops is a kind of high-quality organic fertilizer, which plays an important role in crop rotation. In recent years, the project of green fertilizer to enhance soil organic matter has been advocated and developed by the state. In organic agriculture, planting green fertilizer seeds is not only an effective way to increase fertilizer sources, but also plays a key role in soil improvement, thereby improving the physical and chemical properties of the soil, which is conducive to future growth. At present, the common green fertilizer seeds are:White clover,Red clover,Crimson clover,Orchar.