A device provided by the invention is simple in structure and is convenient to use. The water temperature of well water is generally lower than the water temperature of surface water, and the mineralization degree of well water is higher than the mineralization degree of surface water. Water molecules can be reduced by magnetizing well water, and physical and chemical properties such as conductivity, surface tension and the like can be changed, so that fertilizers can be mixed better. After a water flow is heated, microbial activity of soil can be improved, antioxidant enzyme activity of cropsis increased, root activity of the crops is enhanced, and therefore, the effect of increasing the yield of crops is achieved.