Mean annual temp. (˚C)

>25

22 - 25

20 - 22

18 - 20

<18

Relative humidity (%)

>75

70 - 75

60 - 70

-

<60

Topography (t)

Slope (%)

0 - 8

8 -16

16 - 30

30 - 50

>50

Wetness (w)

Drainage class

Moderate to

Imperfect

Well and

somewhat

excessive

Poor (aeric)

(easily

drained)

Poor (typic)

(difficult

to drain)

Very poor

Flooding

Not flooded

Not flooded

Minor

Moderate

Severe

Soil physical properties (s)

Texture/structure

CL, SCL, L

SCL

SCL - LFS

Any

C, CS

Coarse fragments (Vol %) 0 - 10 cm

<5

5 - 15

15 - 35

35 - 45

>45

Depth (cm)

>100

75 - 100

50 - 75

25 - 50

<25

Soil fertility conditions (f)

CEC (meq/100g)

≥16

<16

-

-

-

pH topsoil

5.0 - 5.8

4.5 - 5.0; 6.0 - 7.0

4.0 - 4.5

<4.0, >7.0

<4.0, >7.0

Base saturation (%)

>35

20 - 35

<20

-

-

Organic carbon (%) 0 - 15 cm

≥1.5

<1.5

-

-

-

Mg: K ratio

>3.5

2 - 3.5

1 - 2

-

-

K (mole fraction)

>1.75

1.5 - 1.75

1.2 - 1.5

<1.2

<1.2

Salinity and alkalinity (n)

EC (dS/m) (50 cm)

<1.0

1.0 - 2.0

2.0 - 3.0

3.0 - 4.0

>4.0