PROFILE STUDIES OF THE SOLONETZ SOILS OF CALIFORNIAby

R. EARL STORIE (1)

Studies made through soil surveys and other fieldwork during the past three or four years have discloseda number of soils in California having the morphologyof the solonetz. The process of solonetz formation is setforth in the works of Glinka (6), Gedroiz (5), Afanasiev(1), and other Russian soil scientists. Glinka (6) definessolonetz as alkali soils with characteristic structure, incontrast with the solonchak soils which are alkali soilswithout any definite structure. He explains that the up-per horizons of the solonchak may contain soluble salts,while the same horizon of the solonetz does not, althoughsalts may be present in the deeper horizons of the solon-etz. Quoting from Glinka (6) : "where NaHCO3 is pre-sent and chlorides absent the following transformationtakes place; NaHCO3 in the surface horizons changes toNa2COs which dissolves humic acid and prevents the floc-culation of the fine grained suspended soil material. Inthis state the material passes downward with a part ofthe alkaline humates. At some depth a change of theNa2CO3 takes place and the alkaline humate is precipit-ated along with the suspended soil material from above,the latter being precipitated through flocculation. Inthis way a leached upper horizon of coarse texture isformed and a lower horizon which on drying breaks upinto columnar, prismatic or irregular shaped pieces."

All the Russian investigators mention the leachedA horizon, the ashy gray lower A horizon, the heavytextured alkaline B horizon of columnar or prismaticstructure, and the lower B horizon in which the frag-ments are more angular and contain considerableamounts of chlorides or sulphates.

Afanasiev (1) places the solonetz in "the group ofSteppe soils that were originally solonchak (saline)", anddescribes them as soils having slightly acid surface hori-zons, with the sesquioxides and clay removed from thehorizon A to the B; the absorptive complex partly sat-urated with sodium, and with the soluble salts and car-bonates in the lower B horizon.

The process of development from a normal soilthrough the saline (solonchak), to the solonetz and fi-nally to the soloti is set forth by Nikiforoff ( 7 ) .

A number of California soils have the well de-veloped structural profile of the solonetz. The texturaland structural sequence of horizons of these soils areso prominent and distinctive that a. person without soilknowledge can readily see the difference between thehorizons and the evidence of migration of materials fromthe A horizon and into the B horizon. (Note charts, andstructural profiles).

Of the soils which we have studied, those havingthe best developed solonetz profiles are the Huerhuero(pronounced Wear-wear-o), Aliso, Stockpen, Merriam,Monserate, Antioch, Olivenhaim, Las Flores, Tierra, Ol-cott, Solano, and Canby series. Approximately a halfmillion acres of these soils have been mapped in Cali-

(1) Assistant Soil Technologist, Univ. of California.

fornia during the past four or five years. Future soilsurveys will no doubt extend this acreage to a consider-able extent.

These soils occupy flat plains and marine terraces.They have a scant grass cover which springs up followingWinter rains but which often dries up soon after therainless dry summer starts. Some low brush interspersedwith short grasses often occurs on the eroded areas onthe marine terrace.

The average annual rainfall where they occur variesfrom 5 to 30 inches, nearly all of which falls during theperiod between October and April. The surface horizonof these soils is usually saturated following heavy rainsand very dry during the rainless season.

Soils of the Solano and Canby series have the char-acteristic "slick spots" which are devoid of any vegeta-tion except a scattering growth of alkali-resistant shrubsand grasses. They occupy flat poorly drained plains.

From the agronomic standpoint all these soils haveproperties which render them of low value. Fairly ex-tensive areas have been planted out to avocados andcitrus in southern California. In these areas the loss oftrees has been large.

Profile #1—Huerhuero fine sandy loam.

The Huerhuero, Aliso, Merriam and Stockpen serieshave the same general sequence of structural and text-ural horizons and occur under an annual rainfall of 5to 15 inches in the arid to semiarid portion of California.The soils in this region are of prevailingly brown orgrayish brown color.

The profile of the Huerhuero fine sandy loam, de-scribed below, was taken midway between Los Angelesand San Diego on a flat marine terrace having a shortgrass cover, and located about 400 yards from the sea(3). A mean annual temperature of 62°F and a meanannual rainfall of 12.85 inches are reported near thesample site.A—O—7" Light grayish brown or light brownish gray

fine sandy loam, structureless except for a slightlyplaty structure on top. The soil material breaksdown readily into a fine grained structure, is acidin reaction, and contains no soluble salts.

B1—7—22" A dark, chocolate brown very compact clayof distinctly columnar structure. The columns are2 to 4 inches in diameter and four to seven inchesin length, having 5 to 8 faces. The tops of the col-umns are slightly rounded where the abrupt changeoccurs between this and the light colored sandymaterial above it. Faces of the columns are coatedwith a dark brown colloidal staining or glazing.Roots follow cracks rather than penetrate the ag-gregates and are flattened out to a considerableextent. More than 80 per cent of the clay is ofcolloidal nature. This horizon is distinctly basic inreaction.

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B2—22—62" Yellowish brown clay loam of cubicalstructure. Cubical aggregates are 2 to 3 inches indiameter, have considerable colloidal glazing on theirsurfaces, and contain seams and nodules of limecarbonate. This horizon is much less compact thanthe one above it. A large part of the clay is ofcolloidal nature.

C—48—72" The C horizon consists of a pale yellowishbrown fairly compact loam which happens to be ofamorphous structure in position but breaks out dryin irregular shaped clods or blocks. The reaction isneutral to slightly basic.

Table 2. Antioch fine sandy loam, Profile #2

C1 — 62" — Pale yellowish brown amorphous sandy loamor loam.

Table 1. Huerhuero fine sandy loam, Profile #1

HorizonAB1B2-

Depth0-7"

7-22"22-62"62-72"

MoistureEquivalent

14.2535.2020.7820.06

TotalClay

12.00

34.9619.5615.29

ColloidalClay7.29

28.1015.3812.60

pH5.167.778.818.04

ReplaceableSodium

none.07.02.08

MoistureHorizon Depth Equivalen

A1 0-18" 18.64A2 18-20" 18.30B1 20-34" 26.82B2 34-48" 22.84C1 48-72" 21.92

Totalt Clay

27.84

46.9031.3824.50

Profile # 3 — Olivenhain

Coastal plain soils

ColloidalClay

10.21

35.8524.3214.50

ReplacpH Sodi

5.63 n<5.906.807.807.60

:eableum3ne

.02

.01

.01

loamy fine sand

of the Olivenhain, Las Flores and

Profile -#2—Antioch fine sandy loam

The Antioch and Olcott series have the same gen-eral sequence of structural and textural horizons, andoccur under an annual rainfall of 15 to 30 inches (2)on marine terraces having a grass cover. Both arecharacterized by deep surface horizons and thick ashygray A2 or A3 horizons overlying the columnar clay B1horizon.

The profile of the Antioch fine sandy loam, de-scribed below, is taken about 50 miles northeast of Berk-eley on a flat plain about 40 feet above the level ofSuisun Bay which is an arm of San Francisco Bay. Amean annual temperature of 60°F and a mean annualrainfall of about 20 inches are reported near the samplesite. (Chart #2)

A1—O—18" Grayish brown to light grayish brown finesandy loam. This horizon lacks structure and has atendency to break up readily toward a fine granularform. The soil is pervious to roots and water. Theinside of root cavities has a light gray coating.

A2—18—20" Light ashy gray fine sandy loam of singlegrained or vesicular structure, high in visible silicaand low in organic matter. Both the A1 and A2 hori-zons are acid in reaction and contain much lesscolloidal clay than the subsoil horizons.

B1—20—34" There is an abrupt transition from theA2 horizon to the tight waxy clay B1 horizon whichhas a columnar or jointed structure when dry. Thetops of the columns are rounded and have the lightgray streaks from the A2 horizon extending intothem for an inch or two. This horizon is of dullbrown color with dark colloidal glazing on the sur-face of the structural aggregates. The columns are4 to 7 inches in length and 2 to 3 inches in dia-meter. The reaction of the upper portion of thehorizon is slightly acid but becomes basic withdepth.

B2—34—48" Light yellowish brown moderately com-pact clay loam of cubical structure. This horizon,when dry, breaks into rather regular shaped cubesabout 2 inches on a side. Gray nodules of limecarbonate give the cubes a mottled appearance. Thesoil material surrounding the nodules are noncal-careous except in root cavities and seams. Althoughhigh in colloidal clay, this material can be brokendown much more readily than the columnar mater-ial of the B1 horizon.

Tierra series (8) all have similar sequence of texturaland structural horizons but differ mainly in color. Thesesoils are developed and rest on a consolidated marinesubstratum. They occur under an annual rainfall of 5to 15 inches. The profile of Olivenhain loamy fine sand,described here, was taken about 30 miles north of SanDiego on a high flat-topped marine terrace having a grasscover in a region with a mean annual temperature of62°F and a mean annual rainfall of 12.85 inches. (Chart#3)

A—O—9" Brown to light brown structureless loamyfine sand of low organic content, slightly acid inreaction, with a very thin layer of light gray vesi-cular sandy material overlying top of B1 horizon.

B—9—27" Dark brown very dense sandy clay of colum-nar structure. Columns vary from 2 to 3 inches indiameter and 4 to 7 inches in length, and have 5to 7 faces. Tops of the columns are slightly roundedbut not so much as in the other profiles discussed.The light gray siliceous coating over the tops ofthe columns is quite thin. Roots follow the cracksrather than penetrate the columns. Considerable col-loidal glazing can be seen on the surface of thestructural aggregates. Over 90 per cent of the clayis colloidal. The lower part of this horizon, whereit rests on the massive substratum, is a little moreangular than the top and contains soluble salts.

C—27"— Brown to light gray consolidated sandstone,like marine substratum. Contains much Cl and SO4.

Table 3. Olivenhain loamy fine sand, Profile#3

Moisture Total Colloidal ReplaceableHorizon Depth Equivalent C.ay Clay pH SodiumA 0-9" 8.66 6.69 3.70 6.26 noneB 9-27" 30.29 40.60 39.26 7.18 .02

Upper part ofC 27-34" 25.43 24.19 22.26 7.04 .01

A large content of soluble salts occur in the Chorizons of all the Olivenhain profiles studied.

Profile #4—Solano fine sandy loam

The Solano soils occupy a flat surface having re-stricted drainage with small broad depressions devoid ofany vegetation and often spoken of as "slick spots."Alkali resistant shrubs and grasses grow on the smallelevations. The average annual rainfall is about 20 in-

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ches and the mean annual temperature about 60°F inthe district where profile #4 is located (4) , which isabout 50 miles northeast of Berkeley. The site is ap-proximately 40 feet above the level of Suisun Bay, anarm of San Francisco Bay. (Chart #4)

A—O—12" Brownish gray structureless fine sandyloam, distinctly acid in reaction. The lower part ofthis horizon is of ashy gray color and of vesicularstructure which is firm but can be easily crushedto a powdery mass. This material is highly siliceous.Less than 50 per cent of the total clay content iscolloidal. Contains no soluble salts or replaceablesodium.

B1—12—26" Dull brownish gray clay. This horizon isencountered abruptly and consists of columns havingrounded tops with the ashy gray sandy material rest-ing as a coating over the biscuit-shaped tops. Thecolumns are 4 to 6 inches in length and 2 to 3inches in diameter. This horizon is very compactand when moist is extremely sticky and resistantto the penetration of moisture. Colloidal glazing isin evidence on the surface of the structural aggre-gates. The reaction of this horizon is distinctly basic,containing bicarbonates. There is considerable alkalipresent and replaceable sodium is present in a fairquantity. About 70 per cent of the clay is colloidal.

B2—26—38" Light grayish brown or light brownishgray clay which is of highly colloidal nature, butbreaks up into a cubical or cloddy structure. Thecubes are from 2 to 3 inches in diameter, containconsiderable colloidal glazing on the surface, butcan be broken much easier than the columns fromthe horizon above. This horizon contains lime car-bonate in seams and nodular form, more than 70per cent of the clay is colloidal.

C1—38—72" This horizon is light brownish gray, mod-erately compact massive material of heavy texturewhich contains considerable lime carbonate and sul-phate. The amount of replaceable Ca increases withdepth.

Table 4. Solano fine sandy loam, Profile #4

MoistureHorizon Depth Equivalent

AB1,B2C1

0-12"12-26"26-38"38-72"

15.647.150.047.0

TotalClay

15.0535.6035.2029.71

ColloidalClay7.32

24.4426.5222.18

ReplaceablepH Sodium

5.37.58.49.2

none.08.08.01

Note the correlation in the above table and in thestructural profile; between the pH, replaceable sod-ium and the structure.

Summary of Profile Characteristics

1. The A1 and A2 horizons of the solonetz soilsmentioned are of slightly platy or granular structurewhere any structure is developed—has a pH of 5.0 to6.5, and is usually of loamy sand or fine sandy loamtexture.

2. The As horizon, often occurring as a dust coat-ing over the top of the heavy textured B1 horizon, is of

light gray color often of vesicular structure, and breaksdown into a powdery mass with slight pressure. In theAntioch series this is 1 to 3 inches in thickness but oc-curs only as a coating in some of the southern Californiasoils. pH of 5.0 to 6.5. Very sandy and high in visiblesilica.

3. The B1 horizon consists of dense clay or sandyclay that dries out into distinct columns 1½ to 2½inches in diameter with 4 to 6 faces and 3 to 7 inches inlength. The tops of these columns are rounded, with asharp line of demarcation between the light texturedsurface. Columns often break up into cubical aggregateswhen force is applied. Roots follow along the faces ofthe columns rather than penetrate them. Colloidal glaz-ing and staining occurs on the faces. Colloidal clay makesup from 70 to 95 per cent of the total clay content.Volume weight=1.80 (approximately 30% pore space).pH varies from 6.0 to 6.5 in the degraded solonetz andfrom 6.5 to 8.0 in the normal solonetz.

4. The B2 horizon normally is of heavy texturesimilar to the B1 but breaks up into cubes or angularfragments which are less compact than the B1 horizon.Accumulation of CaSO4, CaCO3, and varying amounts ofsoluble salts may be present. Where the pH goes above8.5, the soil becomes softer and less plastic, althoughihe amount of colloidal clay is still high.

5. The B3 or C1 horizon often contains some limecarbonate, as well as sulphates and chlorides. pH rangesfrom 6.5 to 8.0.

The C horizon of the Olivenhain group (profile#3) consists of consolidated marine sediments, fairlyhigh in soluble salts.

Literature Cited

(1) Afanasiev, J. N. 1927. The classification problemin Russian soil science. Russian Pedological Inves-tigations No. V, Academy of Science of the U.S.S.R. (printed in English)

(2) Carpenter, E. J., and S. W. Cosby. Soil Survey ofthe Suisun Area, California. U. S. Dept. Agr. Bur.Chem, and Soils, 1931. (unpublished)

(3) Carpenter, E. J., and R. Earl Storie. Soil Surveyof the Capistrano Area, California, 1929. (unpub-lished)

(4) Cosby, S. W., and E. J. Carpenter. Soil Survey ofthe Dixon Area, California, 1931. (unpublished)

(5)

(6)

(7)

(8)

Gedroiz, K. K. 1925. Soil absorptive complex andsoil absorbed cations as a basis for genetical soilclassification. Publication of Nosovka Agr. Exp.Sta. No. 38.

Glinka, K. D. The Great Soil Groups of the World(Trans, by C. F. Marbut). Edwards Bros., Ann Ar-bor, Michigan.

Nikiforoff, C. C. 1930. Solonetz and solonchaksoils of the Red River (Minn.-Dak.). Bulletin VI,American Soil Survey Association.

Storie, R. Earl, and E. J. Carpenter. Soil Surveyof the Oceanside Area, California, 1929. U. S.Dept. Agr. Bur. Chem, and Soils (unpublished).

Page. 45

STRUCTURAL PROFILES

Profile No. 1 Profile No. 2

STRUCTURAL PROFILES

Profile No. 3 Profile No. 4

C

lit H^AAcolumnar —

38

slightly platy

columnar

bical

C1,

46