Use of a Nitrogen Index With Broad National and International Applicability to Increase Nitrogen Use Efficiency.

Nitrogen inputs significantly contribute to increased yields, food security, and the economic viability of agricultural systems. This is due to the fact that most agricultural systems are nitrogen deficient, and nitrogen is essential to so many physiological functions in plants. One factor that complicates nitrogen management is that this nutrient is very dynamic and can be lost from the system in many different ways, such as via denitrification, leaching, and volatilization. The rate of losses from the system is a function of many physical, chemical, climatic and biological factors. This complexity makes the management of nitrogen to maximize yields while reducing the risk of reactive nitrogen losses to the environment a difficult task. The Nitrogen Index can aid in the assessment of risk of nitrogen losses to the environment. This tool has been validated and calibrated across several regions and countries, and it has been found to be capable of quickly assessing the risk of nitrogen losses. The tool can currently be used in the English and Spanish languages, and will soon be available in Portuguese. The tool may also become available in additional languages with future releases. The tool is being used across the USA (e.g., it is being used by NRCS in Kentucky as part of the state's nutrient management plans), and in Mexico, Ecuador, and other countries. The tool has new features such as a Phosphorus Index and the capability to quickly estimate nitrogen use recommendations for a given site. It can also now be used to assess the effects of management on N₂O emissions and carbon sequestration equivalents. Examples will be presented on the potential to use this tool to quickly assess the risk of nitrogen losses to the environment, to reduce nitrate leaching and N₂O emissions, and to increase nitrogen use efficiency.