System Nitrogen Efficiency Framework

\[ NUE_{Crop} =\frac{Nyield}{Ninflow} \]

\[ NUE_{Soil} =\frac{Noutflow}{Ninflow} \]

\[ NUE_{Loss} =\frac{Nyield}{Noutflow} \]

• \(N yield\) = N removed in harvested mass
• \(N inflow\) = Fertilizer + Deposition
• \(N outflow\) = Non-BNF grain N + Leaching + Denitrification

Workflow

Experimental Sites

So far we have Nashua and Kelley (COBS)

Model training and testing: Yields

Model training and testing: Flow-weighted N conc. in drainage

Model training and testing: Drainage

Model training and testing: Tile Leaching

Corn-soybean NUE indices

FPF= DMyield/fertilizer; UpE = uptake/fertilizer; UtE = DMyield/uptake

Corn-soybean correlation between NUE indices

Latitudinal changes in NUE across cropping system: Temporal

Latitudinal changes in NUE across cropping system: N mgmt