The method of quickly predicting longevity of controlled release fertilizer coated with heat-solidified resin

Pattern of accumulative nutrients release rate from coated controlled release fertilizer(CRF),Osmocote,was tested at 25℃,40℃,60℃,70℃,80℃ and 100℃ respectively to study and establish a quick method to predict longevity of CRF by use of regression equation.Results showed that the pattern of accumulative nutrients release curve would fit one factor quadric regression equation at each given temperatures,and all of R2 was bigger than 0.996.There was a significant negative correlation between temperature and the longevity of the CRF,which the one factor quadric regression equation could also be used to describe the relationship,and its R2 was greater than 0.993.The regression equation between temperature and the longevity could be applied to predict longevity of CRF within a relatively short period of 3 to 8 hours.Based on this one variable factor quadric regression equation the longevity of CRF could be quickly and precisely predicted,and the difference of longevity between the measured and the predicted one is only 2.4 days.However,the difference of longevity between measured and predicted by use of widely or commonly applied method of differential release rate is 29 to 42 days.It could be concluded that the one variable factor quadric regression equation method is more superior to the commonly used one of differential release rate.Longevity of coated CRF could be quickly and precisely predicted in a few hours by application of one factor quadric regression equation method.This method could also be applied to quality control of coated controlled release fertilizer production online and to test CRF quality in the fertilizer market.