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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。
OBJECTIVE: To prepare biodegradable puffed slow-release fertilizer by using industrial and agricultural wastes that do not cause secondary pollution such as deteriorated corn and oil feet as sustained-release materials and using the formed three-dimensional framework structure to encapsulate fertilizer particles such as urea. Methods: The modified release materials were quenched, puffed, crushed, extruded and granulated to have a three-dimensional framework structure. The purpose of controlling the release rate of the fertilizer was achieved by changing the process conditions and the types and proportions of the raw materials, and adjusting the three-dimensional framework structure and size . Results: The samples of puffed slow-release fertilizer were prepared by this method. The three-dimensional skeleton structure formed a dense protective layer on the surface of fertilizer particles (urea encapsulation rate> 85%, pinhole number> 20% Thickness> 30 nm), the sample degraded and slipped off with the protective layer in the soil, and the fertilizer particles gradually exposed and dissolved into the soil. The releasing process of puffing and slow release fertilizer is continuous degenerative-exfoliation-dissolving phenomenon from the outside of the grain to the core, and will not produce the residue that pollutes the environment during the whole releasing process. Pure urea (100%) was soaked in water for 10 min to dissolve completely, while the sample with urea 81.5% released only 8.2% after 120 min; pure urea (100%) dissolved 85% in soil after 20 h, 81.5%, 40.9% of the puffed slow-release fertilizer released by the same time 1.3%, 0.8%, the release rate of only pure urea 1 / 65.38,1 / 106.25. CONCLUSION: The release rate of puffed and slow-release fertilizer in water and soil is obviously reduced (taking pure urea as reference), biodegradability (biodegradation rate> 95%) can increase the content of organic fertilizer in soil and improve soil structure .