ISO 21263:2017规定了一种测定包膜肥料养分缓释特性的方法。不包括生物或微生物机制引起的pH依赖性水解和降解。 规定的方法仅适用于通过非生物过程释放任何营养素的产品（即通过物理机制释放营养素的产品）。微生物对涂层（例如硫涂层肥料）的侵蚀及其后果无法通过所述技术进行测量。 该方法涉及一个漫长的过程，可能不适合日常测试。如果加速方法与本文件相关，则可以使用加速方法。附录B中描述了此类加速方法的一个示例。回归分析也可用于此目的。

ISO 21263:2017 specifies a method for the determination of the slow release properties of nutrients from coated fertilizers. pH-dependent hydrolysis and degradation by biological or microbial mechanisms are excluded. The specified method is only applicable to products releasing any nutrients by means of a non-biological process (i.e. those where the nutrients are released by a physical mechanism). Microbial attack on the coating (e.g. sulfur coated fertilizers) and the consequences thereof are not measurable by the technique described. This method involves a lengthy process which may not be appropriate for day to day testing purposes. Accelerated methods can be used provided they are correlated with this document. An example of such an accelerated method is described in Annex B. Regression analysis can also be used for this purpose.