Table 2 Spectral indices of DOM extracted from 59 soils of four soil types under two land-uses (natural land and cropped land) across China

59

1.49 ± 0.68

0.77 ± 0.10

0.79 ± 0.14

1.73 ± 0.15

16

2.03 ± 0.48a

0.92 ± 0.02a

0.60 ± 0.05b

1.60 ± 0.06b

7

1.99 ± 0.32

0.91 ± 0.01

0.59 ± 0.05

1.63 ± 0.04

9

2.05 ± 0.60

0.92 ± 0.03

0.61 ± 0.04

1.57 ± 0.07

14

1.52 ± 0.64ab

0.86 ± 0.03a

0.66 ± 0.06b

1.69 ± 0.06b

5

1.24 ± 0.14

0.85 ± 0.03

0.70 ± 0.07

1.68 ± 0.06

9

1.67 ± 0.76

0.87 ± 0.03

0.64 ± 0.03

1.71 ± 0.04

18

1.10 ± 0.54b

0.79 ± 0.05b

0.77 ± 0.11a

1.81 ± 0.14a

11

1.29 ± 0.72b

0.75 ± 0.14b

0.88 ± 0.19a

1.88 ± 0.16a

4

1.59 ± 0.74

0.70 ± 0.08

0.77 ± 0.08

1.91 ± 0.15

7

1.12 ± 0.71

0.78 ± 0.16

0.84 ± 0.16

1.83 ± 0.17