Study on the characteristics of nutrient releasing of the coated urea with tung oil as controlling materials

The captive test in the water and the potted planting experiment were used to study the nutrients releasing dynamics of polymer-coated-released fertilizer. The result shows that the preliminary solubility rate of nitrogen of tung oil-coated urea is 12.6% in the soil and 20.1% in the water meaning that tung oil is a preferable coating materials. The ratio of the releasing periods in the water to in the soil is 1:1.2. The kinetics equation of LOGISTIC could be used to express the nutrient release characteristics. The nitrogen release rate can be reflected by the velocity coefficient k.