Table 1 Mixed-effects model of the effects of mean annual temperature (MAT), maize planting density (number of plants per hectare, PPH), initial soil organic carbon (SOC), and water (W) and nitrogen (N) input on yield, water productivity (WP) and N use efficiency (NUE).

Yield (t ha⁻¹)

α (intercept)

4.22

1.45

901

2.91

0.004

β₁ (MAT)

−0.25

0.05

35

−4.45

<0.001

β₂ (PPH)

<0.001

<0.001

901

3.81

<0.001

β₃(SOC)

0.01

0.06

901

0.10

0.92

β₄ (W)

0.01

<0.001

901

6.62

<0.001

β₅ (N)

0.01

0.002

901

5.10

<0.001

β₅ (W × N)

<0.001

<0.001

901

0.25

0.80

WP (kg m⁻³)

α (intercept)

2.30

0.36

913

6.38

<0.001

β₁ (MAT)

−0.05

0.01

36

−4.04

<0.001

β₂ (PPH)

<0.001

<0.001

913

2.32

0.02

β₃(SOC)

−0.01

0.01

913

−0.94

0.35

β₄ (W)

−1E-03

<0.001

913

−7.22

<0.001

β₅ (N)

0.004

<0.001

913

8.77

<0.001

β₅ (W × N)

−5E-06

<0.001

913

−5.18

<0.001

NUE (kg kg⁻¹)

α (intercept)

105.2

19.07

703

5.51

<0.001

β₁ (MAT)

−2.53

0.67

35

−3.77

<0.001

β₂ (PPH)

<0.001

<0.001

703

2.48

0.01

β₃(SOC)

−1.66

0.72

703

−2.31

0.02

β₄ (W)

0.05

0.01

703

4.42

<0.001

β₅ (N)

−0.24

0.03

703

−7.24

<0.001

β₅ (W × N)

−1E-04

<0.001

703

−2.19

0.03