Supplementary information

Table S1 Heterogeneity of groups in each explanatory variable

Database

Explanatory variables

Crop fertilizer-N recovery

Soil Residual fertilizer-N

Qbetween

Qtotal

Prob

Qbetween

Qtotal

Prob

UI

UI species

0.509

9.927

0.065

0.173

2.499

0.065

N application rate

0.581

8.049

0.0730

0.051

2.298

0.668

N application times

0.635

10.249

0.125

0.199

2.865

0.013*

Field condition

1.012

9.237

<0.001*

0.299

2.865

0.003*

Soil pH

0.485

9.542

0.088

0.053

2.319

0.436

Soil organic matter

0.256

6.450

0.427

0.142

1.226

0.085

Soil texture

0.517

10.041

0.077

0.016

2.746

0.792

NI

NI species

0.873

18.901

0.531

0.699

11.335

0.117

N application rate

0.879

18.273

0.337

0.799

12.566

0.211

N application times

0.139

19.006

0.405

0.851

12.578

0.022*

Fertilizer types

1.106

19.006

0.059

1.762

12.578

0.009*

Field condition

2.563

19.006

<0.001*

0.189

12.578

0.306

Soil pH

0.478

18.643

0.333

0.009

11.818

0.972

Soil organic matter

0.233

4.817

0.253

0.905

11.445

0.198

Soil texture

1.297

15.059

0.038*

1.634

11..469

0.013*

Overall

2.847

35.129

<0.001*

0.515

17.666

0.081

Database

Explanatory variables

Total fertilizer-N recovery

Unaccounted fertilizer-N

Qbetween

Qtotal

Prob

Qbetween

Qtotal

Prob

UI

UI species

0.192

4.164

0.161

2.936

37.348

0.071

N application rate

0.396

3.091

0.021*

0.663

30.209

0.736

N application times

0.274

4.218

0.017*

0.192

37.726

0.581

Field condition

0.278

4.218

<0.001*

0.302

37.726

0.495

Soil pH

0.211

3.962

0.133

6.371

36.206

0.005*

Soil organic matter

0.084

2.832

0.628

3.116

29.609

0.166

Soil texture

0.086

4.044

0.429

1.717

63.929

0.412

NI

NI species

0.484

10.123

0.197

2.162

66.746

0.267

N application rate

0.749

10.393

0.170

0.182

67.557

0.981

N application times

0.262

10.400

0.182

0.439

67.564

0.459

Fertilizer types

1.492

10.400

0.010*

0.762

67.564

0.562

Field condition

0.599

10.400

0.044*

3.871

67.564

0.379

Soil pH

0.166

9.892

0.599

0.490

66.963

0.742

Soil organic matter

1.251

9.619

0.051

1.582

59.237

0.651

Soil texture

1.869

9.988

0.005*

1.717

63.929

0.415

Overall

0.569

16.824

0.051

5.126

115.323

0.022*

Note: * means the groups in relative explanatory variable being significant difference.

Table S2 Changes of the effects of N stabilizers on the fertilizer-N fate in the soil-crop system under different study method

Variables

Categories

Number

Means

Lower CI

Upper CI

Qbetween

Prob

UI amendment

Crop recovery

Field

39

18.06

10.72

26.06

0.27

0.10

Pot

60

27.77

20.76

35.59

Soil retention

Field

32

8.43

2.99

14.61

0.05

0.24

Pot

49

4.43

0.92

8.09

Total recovery

Field

33

11.18

6.24

16.46

0.18

0.05

Pot

49

19.42

14.1

25.51

Unaccounted

Field

33

-19.85

-30.67

-7.30

0.13

0.06

Pot

49

-37.13

-49.72

-26.52

NI amendment

Crop recovery

Field

72

13.10

4.79

21.99

0.20

0.32

Pot

37

5.51

-3.94

19.90

Soil retention

Field

51

16.10

5.71

28.61

0.03

0.70

Pot

26

12.70

5.07

21.07

Total recovery

Field

51

14.47

5.58

25.43

0.40

0.11

Pot

27

2.02

-5.08

10.05

Unaccounted

Field

51

-12.05

-21.99

-2.40

0.22

0.62

Pot

27

-19.28

-48.21

13.45

DI amendment

Crop recovery

Field

10

35.66

12.91

42.42

0.32

0.06

Pot

6

73.24

37.86

164.77

Soil retention

Field

8

16.39

3.41

35.34

0.24

0.17

Pot

6

-3.52

-29.76

15.59

Total recovery

Field

8

13.78

2.29

33.91

0.31

0.06

Pot

7

40.86

27.38

68.83

Unaccounted

Field

8

-22.31

-36.75

-2.08

0.58

0.05

Pot

7

-55.12

-61.81

-36.32

Table S3 Changes of the effects of N stabilizers on the fertilizer-N fate in the soil-crop system under different sampling procedure

Variables

Categories

Number

Means

Lower CI

Upper CI

Qbetween

Prob

UI amendment

Crop recovery

Premature

29

16.18

9.31

24.09

0.29

0.06

Mature

70

28.13

21.35

35.91

Soil retention

Premature

23

4.19

-1.44

10.87

0.02

0.47

Mature

58

6.63

3.07

10.16

Total recovery

Premature

24

11.40

7.85

15.99

0.14

0.08

Mature

58

18.93

13.30

25.06

Unaccounted

Premature

24

-53.87

-22.86

-38.49

0.57

0.34

Mature

58

-37.71

-21.92

-30.04

NI amendment

Crop recovery

Premature

10

15.65

5.76

25.27

0.04

0.64

Mature

99

10.03

3.00

18.38

Soil retention

Premature

6

15.27

0.19

33.88

0.00

0.99

Mature

71

14.97

6.77

23.84

Total recovery

Premature

6

18.12

4.78

35.17

0.05

0.60

Mature

72

9.63

2.70

17.82

Unaccounted

Premature

6

-22.11

-39.82

-7.17

0.09

0.70

Mature

72

-13.89

-27.75

-0.37

Note: the observation data from DI amendment obtained from maturity sampling procedure.

Table S4 BRT model running parameters and outputs

Process

Database

Learning rate

Bag fraction

CV deviance

CV correlation

Number of trees

Crop

UI

0.005

0.75

0.045±0.009

0.648±0.101

2700

NI

0.005

0.75

0.067±0.012

0.617±0.072

950

Soil

UI

0.005

0.75

0.02±0.004

0.251±0.112

1500

NI

0.005

0.75

0.058±0.008

0.43±0.158

5450

Total

UI

0.005

0.75

0.012±0.002

0.754±0.08

6450

NI

0.005

0.75

0.039±0.01

0.628±0.103

7150

Fig. S1 Partial dependence plots (left column) and fitted values (right column) of explanatory variables for crop fertilizer-N recovery under UI amendment.

Fig. S2 Partial dependence plots (left column) and fitted values (right column) of explanatory variables for crop fertilizer-N recovery under NI amendment.

Fig. S3 Partial dependence plots (left column) and fitted values (right column) of explanatory variables for retention fertilizer-N in soil under UI amendment.

Fig. S4 Partial dependence plots (left column) and fitted values (right column) of explanatory variables for retention fertilizer-N in soil under NI amendment.

Fig. S5 Partial dependence plots (left column) and fitted values (right column) of explanatory variables for total fertilizer-N in soil-crop system under UI amendment.

Fig. S6 Partial dependence plots (left column) and fitted values (right column) of explanatory variables for total fertilizer-N in soil-crop system under NI amendment

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