Table 6.

Evaluation metrics for the implemented models for nitrogen estimation.

Model	FS1			FS2			FS3			FS4
	R2	MAE	RMSE	R2	MAE	RMSE	R2	MAE	RMSE	R2	MAE	RMSE
GPR	0.999	0.0305	0.119	0.998	0.0562	0.189	0.95	0.115	0.345	0.93	0.214	0.759
ER	0.97	0.194	0.482	0.98	0.197	0.454	0.91	0.452	0.956	0.92	0.241	0.901
TR	0.97	0.282	0.531	0.97	0.198	0.523	0.9	0.458	0.898	0.9	0.526	0.918
NNR	0.77	0.793	1.082	0.79	0.642	1.325	0.61	0.889	1.185	0.62	1.101	1.004
SVMR	0.65	0.861	1.154	0.68	0.785	1.552	0.54	1.001	1.201	0.58	1.165	1.198