FUE	fertilizer use efficiency
GWR	geographical weighted regression
SFA	stochastic frontier analysis
NUE	nitrogen use efficiency
CS-PNM	canopy sensor-based precision N management
DEA	data envelopment analysis
EKC	environmental Kuznets curve
PGDP	per capita gross domestic product
TE	technical efficiency
GNP	gross national product
OLS	ordinary least square
CO2	carbon dioxide
CV	cross-validation
AIC	Akaike information criterion
VIF	variance inflation factor
C-D	Cobb–Douglas
LR	likelihood ratio