包膜缓释氮肥能够提高氮率利用率，减少氮肥施用对环境造成的负面影响而受到广泛关注。缓控释效果好、价格低廉、环境友好的膜材料研发已成为包膜缓释肥料领域研究热点。本项目采用有机高分子聚合和溶液共混技术以成膜性好、可降解的聚乙烯醇、聚乙烯吡咯烷酮共聚物为成膜剂，以比表面积大、吸附性强的生物炭为填充物制成水基共聚物-生物炭复合膜材料，通过测定膜材料疏水性、力学特性、微形态等指标明确各组分适宜配比和合成条件；采用流化床工艺对颗粒尿素（15N标记）进行包膜，制备包膜缓释氮肥。利用红外光谱仪和扫描电镜技术结合养分溶出特征，明确该膜材料对养分控释机理；采用土箱微区的试验方法，利用15N稳定性同位素示踪技术阐明所研制的新型包膜缓释氮肥氮素在土壤-作物系统中迁移转化规律，揭示该包膜缓释氮肥提高氮素利用效率的机理。研究结果为价格低廉、环境友好、养分控释效果好的包膜缓释肥料研发和应用提供科学依据。

Coated nitrogen attracted extensive attention worldwide since it can improve nitrogen use efficiency and reduce the negative impact of nitrogen applying on the environment. The research and development of membrane material which is inexpensive, environment friendly, nutrient release effectively has become a hot topic in the field of coated slow-release fertilizer. .The copolymer of polyvinyl alcohol which is easy to be filmed and biodegradable and polyvinylpyrrolidone will be used as film-formed agent by the technologies of organic polymer polymerization and solution blending. Biochar which has big surface area and high adsorption capacity will be used as stuffing to produce aqueous copolymer/biochar composites. The suitable ratio of all fractions and synthesis conditions will be determined by measuring hydrophobicity, mechanical property and micromorphology etc. of membrane. Granular urea (15N labeled) will be coated using fluidized bed process to produce slow-release fertilizer. The nutrients releasing mechanisms of this membrane will be confirmed using infrared spectroscopy and scanning electron microscopy combined with nutrient dissolution characteristics. Meanwhile, the increasing of nitrogen use efficiency of coated slow-release fertilizer will be also clarified in this study. These results will provide the scientific basis for the research-development and apply of coated slow-release fertilizer, which has characteristics of inexpensive, environment friendly and nutrient release effectively.