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以淀粉和聚乙烯醇(PVA)为主要原料制备膜材料并包膜颗粒复合肥,通过膜吸水性和肥料抗压碎力试验筛选适合的原料比例制备不同粒径的供试肥料。采用水中溶出率与土壤培养两种测试方法研究了其氮素养分的释放规律,并对两种方法的测定结果进行了比较、分析与评价。结果表明:淀粉与PVA比例合适就会提高膜材料的耐水性和包膜肥料的抗压碎力。超过最佳配比量后的淀粉要比同质量PVA更耐水、更能提高肥料的抗压碎力。自制包膜处理土壤培养法中养分释放率普遍是水溶法中的1/3~1/4,这与介质环境和试验方法的差异有关。调节好淀粉与PVA用量比例或增加膜厚度会使养分释放更趋近于Logistic植物营养生长曲线,同时也使得水、土两介质中测定结果的相关性更好。受多种因素影响,用水溶法现有的一些指标评价包膜肥缓释性能带来误差较大,缓释肥料在水溶法中的释放规律不能真实的反映出其在土壤中的释放性能,对用淀粉、聚乙烯醇这类亲水材料包膜的肥料而言更是如此。
The membrane material and coated granular compound fertilizer were prepared by using starch and polyvinyl alcohol (PVA) as the main raw materials, and the test fertilizers with different particle sizes were prepared by screening the suitable proportion of raw materials through membrane water absorption and fertilizer crush resistance test. The release of nitrogen was studied by using two methods of water dissolution rate and soil culture. The results of two methods were compared, analyzed and evaluated. The results showed that the suitable ratio of starch to PVA would increase the water resistance of the membrane material and the crush resistance of the coated fertilizer. More than the best ratio of starch than the same quality PVA is more water-resistant, more able to improve the resistance of the crush fertilizer. The rate of nutrient release in self-made coating soil culture method is generally about 1/3 to 1/4 in water-soluble method, which is related to the differences of media environment and test methods. Adjusting the proportion of starch to PVA or increasing the film thickness will make the release of nutrients closer to the vegetative growth curve of Logistic plants, and at the same time make the correlation between the measured results in water and soil media better. Affected by a variety of factors, some of the existing indicators of the water-soluble method to assess the slow release of coated fertilizer error caused by the release of slow-release fertilizer in water-soluble law can not truly reflect its release properties in the soil, This is especially true for fertilizers coated with hydrophilic materials such as starch and polyvinyl alcohol.