When you make organic fertilizers, there are many types of raw materials you need. And there will be a lot of sundries in these raw materials. If you compost them directly, it will affect the subsequent production efficiency. Therefore, screening before composting is the pretreatment of raw materials. Sieve out the unproducible materials and leave the materials that can be turned over. This will not only increase your production efficiency, but also help you produce high-quality fertilizer.