The soil needs rest, just like people. China has a large population and little land, and the limited arable land has supported more than one billion people, but it has also paid a great price. At present, most farmland in China is cultivated all the year round and overloaded for a long time, such as wheat and rice in the north and three-season rice in the south. The outstanding problems caused by this are the serious overdraft of cultivated land fertility and the decline of soil quality, which restricts the sustainable development of agriculture. Without soil fertility, seeds can't find the direction of life. Therefore, allowing the soil to have a full rest and implementing the system of rotation fallow is conducive to the recuperation of cultivated land.