Keywords:
Polyurethane; Selenium; Slow-release fertilizer; Assessment test
聚氨酯;硒;缓释肥;评估实验
Abstract:
Many crops have the absorption peak of trace element selenium(Se) in their specific growth period.In order to prepare functional fertilizers matching the release rate of selenium with the absorption rate of crops, the sustained release effect of selenium was evaluated by using polyurethane coated sustained release selenium fertilizer.In this study, water purification experiments were conducted on several kinds of polyurethane selenium fertilizer with different coating quantities at 25℃ and 100℃ to evaluate the sustained release effect of Se element..The results showed that the dissolution rate of Se in fertilizers at 25℃ and 100℃ showed the following laws: the overall trend of the Se release rate in each group was relatively rapid at the beginning, and then tended to be stable, showing three different stages: the rapid release period, linear release period and declining release period. The Se release rates for uncoated Se fertilizer and 2% coated Se fertilizer did not meet the standard of slow-release fertilizer in the early 24 hours, and there was no significant difference between the two groups. The released Se rate for coated fertilizer with 4% and 6% polyurethane could met the standard of sustained-release fertilizer, and the sustained-release period was more than 40 days, and there was no significant difference between the two treatments. The dissolution rate method for Se in fertilizer at 20℃ can be replaced by the more rapid dissolution rate method for Se in water at 100℃.Taking all factors into consideration, 4% coated fertilizer was the optimal solution.
淮山、木薯等作物在其特定生育期对微量元素硒存在吸收高峰,为制备硒释放速率与作物吸收相匹配的功能型肥料,本研究利用聚氨酯包膜缓释硒肥进行了硒元素的缓释效果评估,分别在25℃和100℃下,对几种不同包膜量(未包膜、2%、4%和6%)的聚氨酯包膜缓释硒肥进行静水评估实验,评价各组肥料中硒元素的缓释效果。结果表明,25℃和100℃下肥料中硒的溶出率都呈现以下规律:各组肥料中硒的溶出总体为刚开始较为迅速溶出,然后趋于平稳释放,具有快速释放期、线性释放期、衰退释放期三个明显的阶段。未包膜硒肥与2%包膜量硒肥,24小时初期硒的释放比例不符合缓释肥标准,且两者无显著性差异。4%与6%包膜量硒肥符合缓释肥标准,缓释期在40天以上,两者也无显著性差异。所以25℃和100℃下进行肥料中硒的溶出率评价,两种方法无显著差异,因而可用更为快速的100℃水中溶出率法代替现有的25℃水中溶出率法。综合各方面因素,4%包膜量硒肥是更佳的工艺。