Table 3. The effects of multiple variables on NUE of wheat and maize.

Crop	Item†	Estimate	SD	DF	t value	p value	Sign‡
Wheat	α (Intercept)	59.41	10.51	470.00	5.65	0.000	**
	β1 (Plastic)	5.53	1.72	49.00	3.22	0.002	**
	β1 (Straw)	5.47	1.09	49.00	5.01	0.000	***
	β2 (SOM)	7.99	2.44	470.00	3.27	0.001	**
	β3 (Temperature)	−8E-01	0.53	470.00	−1.60	0.110	NS
	β4 (Water)	5E-02	0.01	470.00	4.55	0.000	***
	β5 (N)	−3E-01	0.03	470.00	−9.40	0.000	***
	β6 (W*N)	−1E-04	0.00	470.00	−1.34	0.182	NS
Maize	α (Intercept)	−1.18	25.97	654.00	−0.05	0.964	NS
	β1 (Plastic)	18.35	3.30	43.00	5.55	0.000	***
	β1 (Straw)	6.20	2.67	43.00	2.32	0.025	*
	β2 (SOM)	10.22	4.43	36.00	2.31	0.027	*
	β3 (Temperature)	1.59	0.97	654.00	1.64	0.102	NS
	β4 (Water)	0.01	0.01	654.00	1.53	0.128	NS
	β5 (N)	−1E-01	0.03	654.00	−3.59	0.000	***
	β6 (W*N)	−5E-05	0.00	654.00	−1.01	0.312	NS

^†See formula (5) for explanation of the items.

^‡“***” means p < 0.001, “**” means 0.001 < p < 0.01, “*” means 0.01 < p < 0.05 and “NS” means p > 0.05.