The Preparation Of Biodegradable Resin Coated Controlled Release Fertilizer

In this experiment, the biodegradable materials were used as membrane materials forpreparing controlled release fertilizer. More than100samples were prepared byspouted-spraying method in fluidized bed film-coating machine. The structure and propertiesof the used biodegradable resins were indenfied by FTIR, DSC, TG, and SEM. The resultshows that the membrane material possesses strong film characteristic flexility and is able toform full film．The film is dense and smooth and the membrane material combines tightlywith surface of urea．The membrane material is able to most suit the surface shape of granuleurea and covers with it tightly． To measure their initial release rate, the water immersion wastested. The nutrient content release and degradation rate of the fertilizer in the soil was alsoconformed. Coated urea fertilizer made by the membrane material has remarkable controllingfunction for urea nitrogen release．CHCl3was used as solvent all through the experiment. The optimum coating processparameters were as follows: air temperature50-60oC, the amount of urea200g/time, thespout pressure0.15-0.2MPa, the injection volume of coating solution2.0-3.0mL/min.Firstly, we chose A as the main membrane material for the coated fertilizer duo to theobvious properties such as complete biodegradable, better film performance, easy processing,and low water permeability. Actually, we found the thermal deformation temperature is toolow and it is easy to adhere between the coating fertilizers. It is still no role after addedmodifiers. Therefore, biodegrable resin B was used as another membrane material to mix withA with different proportion.Before coating, we find a way to identify the optimum ratio range of the two materialsmixed as coating materials. It could save the time of the selection of materials, and thefollowing coating process proved this approach is feasible. Based to the optimum proportionof A and B, the injection concentration and the coating time related to the coating quality werediscussed in detail.The degradation of the membrane materials and nutrient release content were measuredin soil, we found the coated fertilizer release nutrient slowly. The time of controlled releaseabout four months or so, it is fit for crops which has a short growth.