控释肥料膜层孔隙结构是影响养分渗透扩散行为和控释性能优劣的核心因素之一。在观测到控释膜层局部存在微孔的研究基础上，本项目以喷雾包膜和反应成膜两种工艺制备的控释肥料膜层为研究对象，首先建立直接量化测定膜层结构参数的压泡法和压汞法；然后结合水浸泡法、水汽渗透、尿素渗透和扫描电镜等测试技术，定量化研究不同控释膜层的物理孔隙结构特征，以及膜层受浸泡条件影响下的动态变化规律，明确孔隙参数与释放性能的相关关系；最后，根据膜层孔隙特征构建微孔释放的传质模型，并结合试验测定值验证模型计算结果的准确性。以此揭示微孔大小、数量和长度等孔隙特征参数对养分释放速率快慢的制约关系，探明膜层孔隙结构对养分释放速率的影响机制，为调控包膜肥料膜层制备过程、指导控释肥料生产和提高控释肥料产品质量提供理论依据。

The pore structure in the membrane of polymer coated fertilizer is one of the key factors which determine the nutrient diffusion behavior and controlled release quality. This project is based on our previous observation that there exist some local micropores in the controlled release film. The objects of this research are the controlled release membranes which are produced by spray coated and reaction film preparation techniques. Our proposed experiments are, firstly, to quantitatively determine the membrane structure parameters with bubble point and mercury porosimetry methods, and then to furtherly study the membrane structure characteristics using some other analysis experiments such as water dissolution, water vapor permeability, urea permeability, and SEM testing techniques, etc. Based on the above experimental observations, we will analyze the dynamical variation of membrane pore structure under different immersion conditions, as well as the relationship between controlled release properties and the pore structure parameters. Our final goal is to explore the controlled nutrient release mechanism and the determinant factors of the nutrient release rate based on our proposed micropore-flow release model for nutrient diffusion though the membrane and valuable experimental data. These determinant factors mainly include size, number and length of the membrane pores, etc.. The investigation of the nutrient release mechanism through membrane micropores will guide the production of coated fertilizer, regulate controlled release film preparation process and help us improve the quality of coated controlled release fertilizers.