Solonetz (SN)(from R. sol, salt, and etz, strongly expressed)

 

Soils with a dense, strongly structured, clay illuviation horizon that has a high proportion of adsorbed sodium and/or magnesium ions.

Internationally used terms:

`alkali soils' and `sodic soils'

Solonetz soils

Definition of Solonetz

Soils having a natric horizon within 100 cm from the soil surface.

 

Natric horizon• A natric horizon must:• 1. have sandy loam or finer texture and at least 8 percent clay in the fine earth fraction; and• 2. have more total clay than an overlying coarser textured horizon (exclusive of differences which result

from a litholo gical discontinuity only) such that:• - if the overlying horizon has less than 15 percent total clay in the fine earth fraction, the natric horizon

must contain at least 3 percent more clay; or• - if the overlying horizon has 15 percent or more and less than 40 percent total clay in the fine earth

fraction, the ratio of clay in the natric horizon to that of the overly ing horizon must be 1.2 or greater; or• - if the overlying horizon has 40 percent or more total clay in the fine earth fraction, the natric horizon

must contain at least 8 percent more clay; and• 3. have a distinct increase in clay content within a vertical distance of 30 cm if the natric horizon is formed

by clay illuviation. Else, the increase in clay content between the overlying and the natric horizon must be reached within a vertical distance of 15 cm; and

• 4. have no rock structure in at least half the volume of the horizon; and• 5. have columnar or prismatic structure in some part of the horizon, or a blocky structure with tongues of an

eluvial horizon in which there are uncoated silt or sand grains, extending more than 2.5 cm into the horizon; and• 6. have an exchangeable sodium percentage (ESP[1]) greater than 15 within the upper 40 cm of the

horizon, or more exchangeable magnesium plus sodium than calcium plus exchange acidity (at pH 8.2) within the same depth if the ESP exceeds 15 percent in some sub-horizon within 200 cm from the surface of the soil; and

• 7. have a thickness of at least one tenth of the sum of the thickness of all overlying horizons, with a minimum value of 7.5 cm.

•[1] ESP = exchangeable Na x 100 / CEC.

Natric horizon1. have sandy loam or finer texture and

2. have more total clay than an overlying coarser textured horizon and

3. have a distinct increase in clay content within a vertical distance … and

4. have no rock structure in at least half the volume of the horizon; and

5. have columnar or prismatic ….. and

6. have an exchangeable sodium percentage (ESP) greater than 15 within the upper 40 cm of the horizon, or more exchangeable magnesium plus sodium than calcium plus exchange acidity (at pH 8.2) within the same depth if the ESP exceeds 15 percent in some sub-horizon within 200 cm from the surface of the soil; and

7. have a thickness of at least one tenth of the sum of the thickness of all overlying horizons, with a minimum value of 7.5 cm.

ESP = exchangeable Na x 100 / CEC

Natric horizon

1. have sandy loam or finer texture and

2. have more total clay than an overlying and

3. have a distinct increase in clay … and

4. have no rock structure; and

5. have columnar or prismatic ….. and

6. have an exchangeable sodium percentage (ESP) greater than 15 within the upper 40 cm of the horizon, or …and

7. have a thickness with a minimum value of 7.5 cm.

• Most common units:

Vertic*, Salic*, Gleyic*, Mollic*, Alcalic*, Gypsic*, Duric*, Calcic*, Stagnic*, Humic*, Albic*, Takyric*, Yermic*, Aridic*, Magnesic*, Haplic*.

• Association with other soils:• Natric and sodic soils of other great groups

SolonetzVerticSalicGleyicMollicGypsicDuricCalcicStagnicHumicAlbicTakyricYermicAridicMagnesicHaplic

Ochric

Natric

Stagnic

Calcic

gleyic

SolonetzVerticSalicGleyicMollicGypsicDuricCalcicStagnicHumicAlbicTakyricYermicAridicMagnesicHaplic

Calci-Gleyic Solonetz (Stagnic)

natric

ochric

loess

Importance of diagnostics in correlationImportance of diagnostics in correlation

National priorities can be preservedNational priorities can be preserved

natric

ochric

loess

Natraqualf GleyicSolonetz

1

2

3

4

1

2

3

4

1

3

4

1

3

4

End of Solonetz