| The coating properties of controlled-release fertilizers is the key factor influencing the nutrient release, and fast measurement of the nutrient release rate of coated controller-release fertilizers is the important means to evaluate the characteristics of nutrient release. The investigation and evaluation of coating properties of controlled-release fertilizers and the fast measurement of nutrient release could reveal not only the relationship between coating properties and the rule of nutrient release, and the method of fast measurement and evaluation in theory, but also the directly practical meaning and applied value in the exploitation and manufacture of coated controlled-release fertilizers. The characteristics of three different kinds of coated controlled-release fertilizers (thermoplastic resin coated controlled release fertilizers, thermosetting resin coated controlled release fertilizers and polymer Sufur coated urea), the extraction method of nutrient release in water, scanning electronphotomicrograph, stress-extend experiment, etc were applied to investigate and evaluate the relationships between the coating properties and nutrient controlled release. Moreover, the fast measurement of nutrient release rate of the coated controlled-release fertilizer was also determined and evaluated. Main results of the experiments were as followes:1. The nutrient release rates of thermoplastic resin coated controlled release fertilizers and thermosetting resin coated controlled release fertilizers were slower with the coating thickness increased, and the nutrient release longevity was prolonged in turn. Besides, the coating thickness and the nutrient release longevity could be simulated by function relationship.2. The nutrient release rate of thermoplastic resin coated controlled release fertilizers was faster with the proportion of coated penetrating resin increased, and the nutrient release longevity was reduced in turn. The relationships between...
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