New tools for the analysis and characterization of slow-release fertilizers

The commercial development of slow-release fertilizer materials has been incremental and based on use of several unique technologies over the last fifty years. While each technology has found a niche in certain specialty markets, none have found widespread use in broad based agricultural markets. Each technology was addressed, as it was developed, in terms of the regulation and analysis of the specific material. Equipped with an effective method to evaluate a broad range of materials instead of a number of product-specific methods, regulators and the fertilizer industry can begin to monitor these materials efficiently in a laboratory setting. The history of the development of a method aimed at accomplishing this goal is described. Key components in the process were development of an accelerated laboratory procedure, development of a stable laboratory soil incubation method mimicking real-life biological conditions, and the correlation of the data from both new methods.