Atom Conversion Efficiency: A New Sustainability Metric Applied to Nitrogen and Phosphorus Use in Agriculture

Agriculture fertilization suffers from inefficiencies that carry significant environmental and economic consequences. These consequences include high fertilizer production energy demand, on-field greenhouse gas emissions, and eutrophication. Additionally, inefficient fertilizer use is responsible for billions of dollars in annual economic losses in the form of resource loss as well as environmental burdens. Furthermore, the unsustainability of current fertilization practices and the reliance upon finite resources calls into question the ability of agriculture to meet projected increases in global demand. Herein, critical fertilizer system inefficiencies are highlighted and quantified with a new proposed metric, atom conversion efficiency (ACE), which captures inefficiencies of primary nutrient atoms (N and P) at each stage of the fertilizer life cycle, from synthesis to farm gate, for the model crop, corn. Conversion efficiencies for the most common forms of N and P used in conventional fertilizers range from 5% (diammonium phosphate) to 10% (ammonium nitrate). These low system efficiency values motivate advancements in agriculture sustainability through (i) improvements in the conversion of the raw forms of N and P into fertilizers, (ii) enhancement of nutrient use efficiency (NUE), and (iii) nutrient form selection, signaling an opportunity for advancement through innovative technologies.

Duke Scholars

Author Leanne Gilbertson Civil and Environmental Engineering