Table 1.

Regression models and parameters for the relationships between N rate and grain yield, nitrous oxide (N₂O) emission; nitrogen uptake (GNU, TNU), nitrogen recovery efficiency (NRE), net nitrogen balance (NNB), and surplus nitrogen (SN) based on the individual observations when management focused on N rate alone.

Variables	Regression Parameters
	N	Model	Equation	R2	P < F
Grain yield	84	Quadratic	y = 5993+44.4x−0.09x2	0.71	<0.001
N2O	84	Linear	y = 0.28+0.006x	0.43	<0.001
	84	Exponential	y = 0.47exp(0.006x)	0.40	<0.001
TNU	84	Linear	y = 88.4+0.57x	0.61	<0.001
	84	Exponential	y = 98.7exp(0.003x)	0.57	<0.001
GNU	84	Linear	y = 61.7+0.342x	0.65	<0.001
	84	Exponential	y = 67.71exp(0.003x)	0.62	<0.001
NRE	62	Linear	y = 83.98−0.14x	0.14	0.003
	62	Exponential	y = 88.5exp(−0.002x)	0.13	0.002
NNB(GNU)	80	Linear	y = −32.99+0.689x	0.82	<0.001
	80	Exponential	y = 7.5exp(0.013x)	0.71	<0.001
NNB(TNU)	80	Linear	y = −63.26+0.492x	0.59	<0.001
	80	Exponential	y = −107.5+49.6exp(0.005x)	0.61	<0.001
SN	84	Linear	y = −88.35+ 0.433x	0.47	<0.001
	84	Exponential	y = −124.2+42.2exp(0.005x)	0.49	<0.001

N, Number of individual observations; GNU, grain nitrogen uptake; TNU, total nitrogen uptake.