A kind of double-coated environmental friendly fertilizer was prepared by urea as a core, well-mixed keratin and oxidation starch as an inner coating, and superabsorbent polymer as the outer coating. The influence of water absorbency, water retention, and the slow-release behavior of the study fertilizer were investigated. 0.01M CaCl2 immersion extraction and Kjeldahl digestion method were used to measure the content of nitrogen. And the result showed that the nutrient release was 72wt% on the thirtieth day. This result corresponded with the standard of slow release fertilizers of the Committe...
