生物降解型膨化缓释化肥的特点(英文)

Characteristics of biodegradable puffed slow-release fertilizers

目的:采用不造成二次污染的变质玉米、油脚等工农业废弃物为缓释材料,利用形成的三维骨架结构包裹尿素等化肥微粒,制备可生物降解的膨化缓释肥料。方法:缓释材料经过调质、膨化、粉碎、挤压造粒处理,使其具有三维骨架结构,通过改变工艺条件和原料种类、比例,调整三维骨架结构及尺寸,达到控制肥料释放速率的目的。结果:利用该方法制备膨化缓释肥料样品,其中三维骨架结构在化肥微粒表面形成致密的保护层(尿素包裹率> 85%,三维骨架表面大于20 nm 的针孔数量< 20%,骨架网膜厚度> 30 nm),样品在土壤中随保护层受微生物作用降解脱落,化肥微粒逐渐露出并溶入土壤。膨化缓释化肥的释放过程是由颗粒外部向芯部连续发生降解-脱落-溶入现象,整个释放过程不会产生污染环境的残留物。纯尿素 (100%)浸泡在水中经过 10 min 即全部溶解,而尿素含量 81.50%的样品 120 min后仅释放 8.2%;纯尿素(100%)在土壤中经过 20 h 溶解 85%,而含尿素 81.5%,40.9%的膨化缓释肥料经过相同时间释放 1.3%,0.8%,释放速率仅为纯尿素的 1/65.38,1/106.25。结论:膨化缓释化肥在水、土壤中的释放速率明显降低(以纯尿素为参照物);生物降解性好(生物降解率> 95%),可增加土壤中有机肥含量,有利于改善土壤结构。

AIM： Agricultural and industrial wastes, such as deteriorated corns and oil foots, were used as slow-release materials to prepare biodegradable puffed fertilizers, with urea was encapsulated in fertilizer particles with three-dimensional （3D） skeleton construction. METHODS： Slow-release materials formed 3D skeleton construction through modified treatments, swelling, comminution, extrusion and pelleting. Also 3D skeleton construction and its scales were modified by alternating technical conditions, species and ratio of materials in order to realize the controlled-release of fertilizers. RESULTS： Puffed slow-release fertilizers were prepared. And 3D skeleton construction formed as a compact protective layer on surface of fertilizer particles, whose coating fraction of urea was larger than 85%, the number of pin hole （larger than 20 nm） was lower than 20%, and thickness of membrane was larger than 30 nm. The protective layers of samples in soil were biodegraded and pulled out by microbes. Therefore fertilizer particles emerged gradually and dissolved into soil. Slow release of puffed fertilizers was a continuous process containing degradation, abscission and dissolution. And the whole procedure did not yield any polluting residuals. Release experiments in water showed that pure urea （100%） dissolved absolutely in 10 minutes, whereas only 8.2% urea was released from samples with urea content 85.50% after 120 minutes. And similar experiments in soil illuminated that 85% urea was dissolved from pure urea （100%） in 20 hours, whereas 1.3% and 0.8% urea was released from puffed slow-release fertilizers with urea content 81.5% and 40.9% respectively. Therefore, the release rate of slow-release puffed fertilizers was only 1/65.38 and 1/106.25 to that of pure urea. CONCLUSION： Compared with pure urea, the release rates of puffed slow-release fertilizers in both water and soil are apparently low. Furthermore, puffed slow-release fertilizers have good biodegradability （〉95%）, which can improve the construction of soil and increase the content of organic fertilizers.