As environmental and economic pressures continue to drive agricultural efficiency to new levels, nutrient delivery technologies must respond. New and different types of technologies and practices are being developed tomeet these pressures. Once developed they need to be reviewed, categorized and compared. In addition, a better means to asess product claims and develop workable regulations will also be needed. Consequently, surveys of the latest technologies, including their modes of action and agronomic performance need to be compared in practice and the scientific literature. The evolution of these new technologies and products will require improved methods to characterize modes of action, measure nutrient release, and assess bio-availability. Past and current analytical methods typically focus on measuring what is not released; consequently results could not be related to nutrient availability over time. Efforts to develop two methods that provide more information on nutrient release are underway, being fine-tuned, and correlated with each other as well as with agronomic data. A laboratory method measuring accelerated nutrient release in less than a week is undergoing collaboration through AOAC. At the same time an ambient soil method has been developed that uses a biologically active soil system to assess nutrient release. Results of both methods will be presented including assessment of data for current and emerging technologies designed to enhance agricultural efficiency and minimize excess nutrient release to the environment.