Provided are a sustained-release and controlled-release fertilizer having a core-shell structure and a preparation method therefor, which relate to the field of sustained-release and controlled-release fertilizer production. A sustained-release and controlled-release fertilizer having a core-shell structure comprises a core of fertilizer granules and a polyurea-formaldehyde coating layer coated on the surface of the core of fertilizer granules. The molar ratio of urea to formaldehyde in the raw material of the polyurea-formaldehyde is 1-2.5 : 1, and the polyurea-formaldehyde comprises at least polyurea-formaldehyde having 2 to 5 carbon atoms. The molecular weight of the polyurea-formaldehyde can be varied by adjusting reaction conditions so as to form a membrane structure having different carbon chain lengths. The sustained-release and controlled-release fertilizer having a core-shell structure can not only control the sustained release of a large number of nutrients such as nitrogen, phosphorus and potassium, but also can control the sustained release of trace elements such as calcium, magnesium, iron and zinc, and thus can meet nutrient requirements of different crops.
展开▼
