Preparation and slow release effect of coated urea using tung oil as film-forming materials

The paper details the coating of urea granule by using the tung oil as major film forming materials. Through studying the viscosity as well as the viscosity index of tong oil, tong oil/modified resin mixture and their mixtures with inorganic additive, studying the surface and section morphology of coated urea, studying the slow release and fertilizer effect of the coated urea in ryegrass growth, the optimum coating technological conditions of the coated urea were found. The results show that the nutrient release time reaches 24～62 d at 9%%～15% coating ratio with tong oil/E₁ or tong oil/E₃ mixture as coating material, and the product could supply nitrogen nutrients for ryegrass growth in a longer period than ordinary urea, and prolong the green periods of ryegrass growth.