Research advances in slow/controlled-release water-storing fertilizers

The incorporating use of fertilizers with hydrogels is important practice of enhancing efficiency of fertilizer and soil water, and the frontier in international fertilizer research. In the article, a review was given on method and process of fertilizers combined with hydrogels, interaction of fertilizer nutrients with hydrogels and its research methods, and interactive effects of water and nutrients of hydrogels or slow/controlled release water-storing fertilizers(SRWAFs/CRWAFs) applied to soils, and existing problems and future directions to SRWAFs/CRWAFs. Hydrogels can be incorporated with fertilizers into slow/controlled release water-storing fertilizers by physical mixing(absorption or granulation), coating and synthesizing, the process of coating and synthesis is advanced technique to prepare SRWAFs/CRWAFs with high nutrient analysis. Fertilizers and salts influence swelling rate and absorption of hydrogels which depend on fertilizers and salt ionic valence. Reports on slow-release effects of hydrogels and SRWAFs/CRWAFs on nutrients are similar, information about the effects of hydrogels on soil water is conflict which is related to application rate of hydrogels and high salts in soils. From now on, emphasis should be made on criterion of nutrient content and absorbency index, innovation of water-absorbent materials and its incorporation process with fertilizers, and the mechanism of wetting and nutrient controlled-release of SRWAFs/CRWAFs, and also on research of development of pilot-plant and industrialization technology.