Abstract: The methods of pure water dissolving incubation and high temperature drip washing were used to study the pattern of the nutrients release of the CRFs and the regression equations of the periods needed for the same cumulative release rates between 25℃ and 80℃, through which to explore the rapid method to test the CRFs longevity by use of the high temperature drip washing. Results showed that the patterns of cumulative nutrients release curve would fit one factor quadric regression equations at each given temperatures, and all of relative coefficiencies were bigger than 0.995. With the temperature increasing, the nutrients release of the CRFs increased. The CRF’s longevity could be predicted by application of the cumulative nutrients release equation at 80℃ and the regression equation of the periods needed for the same cumulative release rates between 25℃ and 80℃. There were only 0.3~6.9% relative errors difference between the tested CRF’s longevities and the pridicted one. Hence, the longevities of CRFs could more quickly and precisely predicted by use of the high temperature drip washing method than the common differential release rate one. The longevity of coated CRF could be rapidly and precisely predicted in a few hours by application of the high temperature drip washing method.

Key words: Controlled release fertilizer (CRF), Coated with modified natural resin, Longevity of CRF, Rapid test method