Spatial models of topsoil properties in Romania using digital soil mapping techniques

Variable

Classes

1

2

3

4

5

5

7

pH

≤ 5

(strongly acid)

5.1 – 5.8 (moderately acid)

5.9 – 6.8

(weakly acid)

6.9 – 7.2

(neutral)

7.3 – 8.4

(weakly alkaline)

8.5 – 8.8 (moderately alkaline)

EC (mS m^-1)

≤ 12.75

12.76 – 16.49

16.50 – 20.04

20.05 – 24.18

24.19 – 29.11

29.12 – 35.23

≤ 35.24

OC (g kg^-1)

< 7.5

(very low)

7.5 – 17.4

(low)

17.4 – 37.8 (moderate)

37.8 – 61.0

(high)

> 61

(very high)

CaCO₃

(g kg^-1)

0

(no carbonates)

1 – 10

(low)

11 – 40

(medium 1)

41 – 80

(medium 2)

81 – 107

(medium 3)

P (mg kg^-1)

< 4

(extremely low)

4 – 8

(very low)

8 – 18

(low)

18 – 36

(medium)

36 – 72

(high)

> 72

(very high)

N (g kg^-1)

≤ 1

(very low)

1.1 – 1.4

(low)

1.5 – 2.0

(medium 1)

2.1 – 2.7

(medium 2)

2.8 – 6.0

(high)

> 6

(very high)

K (mg kg^-1)

≤ 40 *

(extremely low)

41 – 65 *

(very low)

66 – 130

(low)

131 – 200 (medium)

201 – 300

(high)

> 300

 (very high)

Clay (%)

≤ 25

 (low 1)

26 – 32

(low 2)

33 – 40

(medium 1)

41 – 45

(medium 2)

≥ 46

 (high)

Silt (%)

< 25

(medium 1)

25 – 32

(medium 2)

33 – 40

(high 1)

41 – 50

(high 2)

> 50

(high 3)

Sand (%)

< 15

(low 1)

15 – 25

(low 2)

26 – 35

(low 3)

36 – 56

(medium)

> 56

(high)