Notes About Research Results Available from the NutrientStar Program
Much of the research referenced here on the NutrientStar website was completed on small-plot trials. The majority of studies did not report sufficient information about environmental conditions and practices to enable a full assessment of the nutrient use efficiency (NUE) benefits possible from the use of each product, therefore we report results that suggest the effectiveness of the products based on yield only.
The intent of the NutrientStar program is to assess whether nitrogen stabilizers and decision support tools improve NUE. However, few of the trials applied more than one nitrogen rate, which prevented the calculation of NUE. NutrientStar also attempted to analyze the results of trials based on rainfall, but because few of the trials reported daily rainfall before or after nitrogen application, we were unable to do so, and the yield results were averaged across all trials.
NutrientStar would be better able to assess the conditions under which assessed products might be effective as nitrification inhibitors and/or urea stabilizers if rainfall data had been provided. An assessment could then involve separating the trials into two or more categories emphasizing those where sufficient rainfall occurred in the 30 days after application to leach nitrate from the root zone, which would greatly increase the chance of products improving NUE as nitrification inhibitors, and those where little to no rainfall occurred for two or more days after application, which would greatly enhance the chances of urea stabilizers improving NUE.
The NutrientStar program is committed to promulgating common standards for research and requirements for the minimal data required to allow products and tools to be fully assessed for their ability to improve NUE. Information about protocols required to fully assess products and tools is available here (PDF).