Nutrient Use Efficiency Definitions

Term	Calculation	Reported ranges/examples
PFP: Partial factor productivity of applied nutrient Answers: Did the crop respond to the nutrient input?	Y/F	PFP-N: 40 to 80 kg yield/kg N PFP-P: 100 to 250 kg yield/kg P PFP-K: 75 to 200 kg yield/kg K
PNB: Partial nutrient balance or removal to use ratio Answers: Was more nutrient added or removed from the field?	UH/F	Range will depend on native soil fertility and fertility maintenance objectives < 1 for nutrient deficient systems needing fertility improvement > 1 for nutrient surplus systems ≈ 1 for system sustainability in field with good nutrient availability

F – amount of nutrient applied (as fertilizers, manures, etc.); Y – yield of harvested portion of crop with applied nutrient; UH – nutrient content of harvested portion of crop.

Note reliance on a single nutrient performance indicator can be misleading in the assessment of the efficiency and effectiveness of nutrient management. Performance indicators should be combined with other key information such as known changes or trends in soil nutrient levels or soil fertility, an assessment of the magnitude of the nutrient-limited gap between actual and achievable yield, and evidence of the adoption of nutrient best management practices such as the adoption of soil testing, farmer training, and/or farm record keeping, etc.
Source: IPNI 2014. Issue Review http://www.ipni.net/publication/ireview-en.nsf/0/99B9481CD89B96F585257D95005CE788/$FILE/IssueReview-EN-14061.pdf