低分子量聚乳酸包膜尿素的缓释特性及其减少氨挥发的作用

【目的】制备低分子量聚乳酸包膜尿素，研究其缓释效果和减少氨挥发的作用。【方法】以相对分子质量5 000和10 000的聚乳酸为包膜材料，采用流化喷涂法分别制备包膜尿素，再用石蜡作封闭处理或不处理，制得4种包膜尿素；通过扫描电镜观察包膜结构，采用土柱间歇淋溶的方法研究不同肥料施入土壤后氮素的释放，并通过培养试验观测氨挥发损失。【结果】扫描电镜观察结果表明，两种低分子量聚乳酸均能在尿素颗粒表面成膜，石蜡封闭处理能有效减少包膜中的空隙；在等氮量条件下，包膜尿素处理的氮素淋出量显著小于普通尿素处理（P＜0.01），缓释效果明显；培养试验结果表明，包膜尿素施入土壤后的氨挥发损失也显著小于普通尿素处理。【结论】低分子量聚乳酸包膜尿素是一种环境友好的新型缓释肥料，值得开发应用。

Slow Release Characteristics of the Low Molecular Weight Polylactic Acid-Coated Urea and Its Reduction Effects on Soil Ammonia Volatilization

【Objective】 This paper presented an approach for preparing low molecular weight polylactic acid (PLA)- coatedslow-release urea. The release behavior and reduction of ammonia volatilization after the coated urea added into soil were studied. 【Method】 By spouted-spraying methods, film coated urea fertilizers were prepared with two types of low molecular weight PLA(relative molecular weight-RMW5000 and RMW10000) respectively, retreated with paraffin wax as sealant or not, thus four typesof coated urea were obtained. The structure of coating film was observed by scanning electronic microscopy (SEM), nitrogen releasewas investigated by a soil column leaching method, and ammonia volatilization was determined with an incubation experiment. 【Result】 SEM images showed that both of RMW5 000 and RMW10 000 PLA as a film coated on the surface of granular urea.Paraffin wax used as a sealant could fill up the micro holes or cracks in the coating film. Under the same nitrogen dose added, theamounts of total nitrogen leaching from soil column of the treatments with coated urea were significantly lower than that of thenormal urea treatment, implying that the slow-release effectiveness of coated urea is clear. In the incubation experiment, it was foundthat nitrogen losses through ammonia volatilization of the treatments with coated urea were significantly lower than that of the ureatreatment. 【Conclusion】 Low molecular weight PLA coated urea is a new environment-friendly type of slow-release fertilizer, andits application in sustainable agriculture is prospective.