Digging earth pits, the size of which depends on the number of rapeseed cakes, laying plastic film or mats inside the pits. The crushed rapeseed cake is first soaked in water and the ratio of cake to water is about 1:1; after soaking, it is put into a pit and 500-700 kg of rapeseed cake is loaded per cubic meter. After filling, the top is covered with grass or plastic film and the pressure is about 20 cm above the ground. Two months later, it can be fed.