Device for farmland drainage

The utility model discloses a device for farmland drainage. The device comprises a first substrate and a second substrate, wherein commercial crops are planted on the first substrate and the second substrate. A trench is formed between the first substrate and the second substrate, wherein the substrates are in a long-strip shape, a crop stalk layer is placed in the trench, and a soil layer is placed on the crop stalk layer. The problems that rainfall or irrigation causes fertilizer loss along with water and soil, and rain waterlogging is much, so that crop growth is affected are solved, and the pollution risk, caused by the fertilizer loss, of water environment is reduced. Local materials can be used in the installation process, so that cost is low, husbandry waste is effectively utilized, and the environment pollution problem caused by husbandry waste is also solved. Moreover, crop stalks can further effectively improve the content of nutrients such as organic matters and nitrogen phosphorus and potassium, o