Effect of clays and sodium chloride onthe infiltration of water in sandy soils.

Item Type Thesis-Reproduction (electronic); text

Authors Khattak, Jehangir Khan,1937-

Publisher The University of Arizona.

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EFFECT OF CLAYS AND SODIUM CHLORIDE ON THE

INFILTRATION OF WATER IN SANDY SOILS

by

Jehangir K. Khattak

A Thesis Submitted to the Faculty of the

DEPARTMENT OF AGRICULTURAL CHEMISTRY AND SOILS

In Partial Fulfillment of the RequirementsFor the Degree of

MASTER OF SCIENCE

In the Graduate College

THE UNIVERSITY OF ARIZONA

1969

STATEMENT BY AUTHOR

This thesis has been submitted in partial fulfillment of re-quirements for an advanced degree at The University of Arizona and isdeposited in the University Library to be made available to borrowersunder rules of the Library.

Brief quotations from this thesis are allowable without specialpermission, provided that accurate acknowledgment of source is made.Requests for peLuhission for extended quotation from or reproduction ofthis manuscript in whole or in part may be granted by the head of themajor department or the Dean of the Graduate College when in his judg-ment the proposed use of the material is in the interests of scholar-ship. In all other instances, however, permission must be obtainedfrom the author.

SIGNED:

APPROVAL BY THESIS DIRECTOR

This thesis has been approved on the date shown below:

GORDON R, DUTT Date

Assoc. Professor of AgriculturalChemistry and Soils

ACKNOWLEDGMENTS

The author wishes to express his gratitude to Dr. Cordon R.

Dutt for his guidance, encouragement, and helpful discussion and re-

view of the manuscript. Thanks are extended to Dr. Wallace H. Fuller,

Dr. David Hendricks, and Dr. Donald F. Post for their review and help.

The author also wishes to thank Mr. George Draper and Mr.

Larry L. Broome for their help with the laboratory analyses.

The author is indebted to the United States Department of the

Interior, Office of Water Resources Research, for funds provided in

partial support of this research, as authorized under the Water Re-

sources Research Act of 1964,

111

TABLE OF CONTENTS

Page

LIST OF ILLUSTRATIONS vi

LIST OF TABLES

ABSTRACT

iv

INTRODUCTION . 1

LITERATURE REVIEW 3

THEORY 13

METHODS AND MATERIALS 15

Materials 16

Rainfall Simulator 17

ANALYTICAL PROCEDURES 20

Preparation of Clay Suspension for X-ray Diffraction . . . 20

Determination of Cation Exchange Capacity 20

Exchangeable Cations 21

Determination of Soluble Salts in Artificial Soil 21

Calcium and Magnesium Determination 21

Calcium Determination 21

Carbonate and Bicarbonate 22

Analysis of Runoff Water for Sodium 22

Conductivity of Runoff Water 22

Sodium Determination 22

Chloride Determination 22

Sulphate 23

Determination of Clay in Runoff 23

Determination of Moisture in Artificial Soils 23

Estimation of Exchangeable Sodium Percent FromSoluble Cations 23

RESULTS AND DISCUSSION 25

Calibration of Rainfall Simulator 25

X-ray Diffraction of Clays 25

Cation Exchange Capacity of Colloidal Clay 27

Cation Exchange Capacity, Soluble Ions, and MoistureEquivalent of Artificial Sandy Soils 29

vii

viii

TABLE OF CONTENTS Continued

V

Page

Exchangeable Sodium Percentage and Its Effect on Runoff . 29

Quality of Runoff Water 37

Exchangeable Sodium Percentage and Sodium AdsorptionRatio in the Soils 38

S1JNMARY AND CONCLUSIONS 40

APPENDIX 42

LITERATURE CITED 47

LIST OF ILLUSTRATIONS

Figure Page

Rainfall Simulator 18

Calibration of Rainfall Simulator 19

X-Ray Diffraction of Bentonite, Kaolinite, and IlliteSaturated With Magnesium and Air Dried 26

X-Ray Diffraction of Bentonite and Illite SaturatedWith Magnesium Glycerol Solvated 28

Runoff Versus Exchangeable Sodium Percentage in Soils 33

Percent Increase in Runoff Versus ESP 35

vi

LIST OF TABLES

Table Page

Exchangeable Ions and Cation Exchange Capacityof Clays 30

Exchange Capacity, Soluble Ions, and MoistureEquivalent in Artificial Soils 31

Average Runoff, Electrical Conductivity, SodiumConcentration, and Amount of Clay Eroded 32

Theoretical, Computer Predicted, and ExperimentalESP and SAR 39

vii

ABSTRACT

Calcium bentonite, calcium kaolinite, and calcium illite each

were mixed with salt-free sand in the ratio of 1:9 in order to make

artificial sandy soils. These soils were then treated with sodium

chloride so that they contained 8, 15, and 30 percent exchangeable

sodium, and then subjected to artificial rain. It was observed that

the runoff was increased in the following order with these soils:

bentonitic soil) kaolinitic soil) illitic soil.

Runoff from the bentonitic soil was increased from zero in the

untreated soil to 43.0, 55.6, and 111.3 percent when the exchangeable

sodium percentages were 8, 15, and 30 percent, respectively. Similarly,

runoff is increased from zero to 41.6, 201.0 and 214.0 in the kaolin-

itic soil and from zero to 72.3, 131.5, and 143.4 in the illitic soil

when the exchangeable sodium percentage is changed from untreated soil

to 8, 15, and 30 percent, respectively. The experimental values for

exchangeable sodium percentage were lower than the theoretical values,

due to increased moisture content and erosion of soil.

It was concluded from this investigation that if the artifi-

cial soils used in this work contained from 8 to 15 percent exchange-

able sodium, maximum runoff would be achieved, without producing any

harmful effect to the soil. The quality of the runoff water would be

satisfactory for irrigation purposes.

viii

INTRODUCT ION

Arid and semiarid areas occupy about one-third of the earthts

land. Part of this area is irrigated by water from rivers, streams,

and springs, while the rest is dependent upon the natural rainfall.

It is estimated that the amount of water needed in such areas far ex-

ceeds the present available supply and does not properly satisfy agri-

cultural, municipal, and industrial needs. Usually a part of the

runoff is stored in reservoirs and subsequently used for irrigation.

In most areas it is observed that natural rainfall and water from these

reservoirs are not sufficient for good irrigation practices. Much of

the rainfall water infiltrates into the soil and consequently the run-

off in watershed areas is appreciably decreased.

Various proposals and plans are suggested in Arizona in order

to reduce water shortage for the future - for example, desalting, re-

charging of underground aquifers, and the Central Arizona Project.

These projects are not only expensive, but willtake a long time to

develop. C. B. Cluff and C. R. Dutt (5) showed that by spraying sodium

chloride on sandy watershed areas winter runoff increased twenty-five

times without producing any harmful effect on the soil and vegetation.

The added salt dissolves and moves downward into the soil and interacts

with clay. The clay swells reducing the permeability of the soil and

consequently runoff is increased.

1

The purpose of the present work is to study the type, place-

ment, and amount of clay in sandy soils and the ESP that must be pres-

ent in order to obtain maximum runoff.

2

LITERATURE REVIEW

Early literature r.eviews showed that the effect of various

factors on soil permeability has been known for many years. For

example, Sally (44) observed in Bengal, India, that seepage from the

canals in a heavy clay soil is so slow that the lining was unnecessary.

King (23) and Slichter (46) showed the effect of grain size and par-

ticle arrangement on the permeability of sand. Ellison and Salter (10)

attributed the greater part of the difference between infiltration ca-

pacities of different soils to differences in their aggregation and

clay content. They found that two soils having the same clay content

had different permeability due to soil structure and aggregation.

Similarly, two soils with the same level of aggregation showed permea-

bility difference and were related to clay content.

Salter (45) stated that the permeability of a soil might vary

widely, depending on the extent to which its structure could be main-

tained. Some of the aggregates must be broken down in order to keep

the clay most effective in the sealing process. The fineness of the

aggregates would be an indirect measure of the amount of clay dispersed

in any specific soil, but because the clay content varies from one soil

to another, it is thought necessary to use both the fineness of the

aggregation and the clay content for comparing results for different

soils.

Firman and Bodman (12) showed that a clay loam soil, containing

predominantly kaolinite clay had greater peimeability than a similar

3

soil containing predominantly montmorillonite clay. Both soils showed

a very similar initial permeability, but due to the swelling of mont-

morillonitic clay, permeability decreased more rapidly on the montmor-

illonitic soils.

Huberty and Pillsbury (18) found that fertilizer composed of

ammonia and sodium salt tended to depress the rate of penetration of

irrigation water, whereas calcium fertilizer as well as organic ferti-

lizer tended to increase the rate of penetration of water.

The Emerson (11), Martin and Richard (29), and Reeve (42) in-

vestigations revealed that the presence of divalent ions such as Ca

and Mg in percolating solution generally increased the permeability,

while the presence of Na+ ions in the percolating solution or on the

ion exchange complex frequently decreased the permeability at low salt

concentration.

Harris and Evan (15) studied calcareous soil and deteluLined a

relation between soil permeability and replaceable sodium ions. They

showed that the permeability decreased exponentially as the sodium con-

tent increased. Kelley (22) stated where high-Na irrigation water was

applied, the soil usually remained fairly permeable to the water despite

the undesirable adsorption of Na by base exchange, because of the floc-

culating effect of the salts of the water; but when an irrigation water

of much lojer concentration was substituted, it markedly reduced the

permeability. This point of view was in accord with the laboratory

work of Firman and Bodman (12). Quirk and Schofield (40) saturated

soils with Na, K, Ca, and Mg ions and then successively leached these

soils with more dilute solutions. Below a certain concentration, which

4

is specific for each ion, decreases in permeability of the soils were

observed. The following threshold concentrations were obtained:

2.5 x l0'M NaC1

6.6 x 102M KC1

1.0 x 103M MgCl2

3.0 x 104M CaC12

According to Lutz (28), Antipov-Karatajev reported that the

rate of filtration was a function of the colloid content of the soil

and the filtration velocity through soils depends upon the nature of

the exchangeable ions present. The rate of filtration followed the

series:

Fe> CaMg NH4>' Na

It is apparent from the literature that the swelling and dis-

persion of clay played a very important role in controlling the infil-

tration and/or permeability of soils.

Mattson (30) studied the effect of adsorbed cations on swelling

of soils and found that the swelling followed the ionic series:

Na>'K>Ca>'Mg>Hmethylene blue.

Winterkorn and Bayer (49) showed that the swelling of the col-

bid varies with the nature of the cations on the exchange complex. In

bentonite swelling followed the ionic series:

LiNa)KCa = Ba H

Hoon and Sing (16) treated Kashmir and Jodhpur bentonite with

5.3 and 1.3 percent of sodium carbonate, respectively. As a result,

5

6

their swelling properties were increased, When 3 or 4 percent of the

Kashmir bentonite was mixed with sand, the rate of percolation was re-

duced to 0.12 or 0.05 cc of water per minute, respectively.

Norrish and Quirk (38) used electrolytes to control the swell-

ing of montmorillonite in water suspensions. The Na-montmorillonite

immersed in sodium chloride solution of 4.0, 1,0, 0.5, and 0.3 N showed

x-ray dOOl values of 15.4, 18.7, 18.9, and 40.0 , respectively. The

Ca-montmorillonite immersed in calcium chloride solution of 8.0, 2.0,

and 0.2 N and water showed dOOL spacing of 15.3, 18.7, 19.0, and 19.0

respectively. These results showed that electrolytes could be used as

a convenient means of controlling swelling.

McNeal et al. (34) concluded from their investigation that per-

meability of a soil in the presence of NaClCaCl2 solution decreased

markedly with increasing clay content and with decreasing free iron

-H-. . . -H-

oxide content. Replacement of the Ca in solution with Mg measurably

decreased soil permeability.

McNeal and Coleman (32) showed that swelling would be dominant

in soil containing large amounts of expandable minerals. Dispersion

and translocation would be dominant for decreases in the coarse tex-

tured soil and those containing small amounts of expandable minerals.

Harris (14) studied the effect of moisture content on the de-

gree of di3persion and observed that an increase in soil moisture was

associated with an increase of dispersion on shaking. Kolodny and

Joffee (25) found that dispersion varied with change in moisture con-

tent between the limits of air dryness and saturation, The method of

7

wetting also had a profound effect on the degree of dispersion. This

was illustrated by t.he difference in time required to attain dispersion

equilibrium at a given moisture content,

Browing (4) pointed out that the dispersion of several soil

series investigated was only slightly affected by air drying, In gen-

eral, it could be expected that changes in moisture content would af-

fect the intensity of dispersion in different soils,

Nankayana (37) studied the dispersive behavior of three soils

when treated with different rates of NaC1, Na2SO4, Na2CO3, and Na(P03)6,

The soils differed in the magnitude of deflocculation, Dispersion of

various soils was in the order

Na(PO3)6Na2CO3. Na2SO4 NaCl.

Where the exchangeable Cof the soil was high, Na2CO3 might be as ef-

fective a dispersing chemical as Na(P03)6. The NaCl and Na2SO4 treat-

ment resulted in flocculation of the particles with increasing treatment

rates, possibly caused by an increase in the electrolyte concentration.

On the other hand, the Na2CO3 and NA(P03)6 treatment increased defloc-

culation with increasing rates.

Johnson and Norton (21), working with extremely pure kaolinitic

suspension, showed that for maximum dispersion the medium must be some-

what alkaline. This presented the possibility that the OH ion as such

might have an influence on flocculation and dispersion.

The work of the investigators (22, 32, 38, 40), which was men-

tioned earlier, is in agreement with the theories of Helntholtz, Gouy,

and Stern (in H. Van Olphen, 39; and in Taylor and Glasstone, 43).

Helmholtz suggested that an electrical layer is generally

formed at the surface of separation between two phases. By making the

assumption that the double layer is virtually an electrical condenser

with parallel plates no more than a molecular distance apart, he de-

rived the following equation:

4'd7r(1)

whet e

is the zeta potential

d is the thickness of the double layer

6 is the charge density

is the dielectric constant of the water.

Gouy (in H. Van Olphen, 39) developed a theory of the diffused double

layer at a planar surface. The concentration of the counter ions is

highest in the immediate vicinity of the surface and decreases at first

rapidly and then asymptotically to the inner solution of uniform compo-

sit ion.

Using Maxwell, Boltzman, and Poisson's equations, Gouy obtained

the following expressions:

where

46-lr

1000 kT

8 Ne2p i7

8

2/1 =

c concentration of cations

z = valency of cations

e = electronic charge

T absolute temperature

k Boltzman constant

N Avogadro's Nurtiber

It is clear from equations 1, 2, and 3 that is equivalent to

thickness of the double layer In other words, - gives the thick-

ness of the equivalent Helntholtz double layer. We can relate equations

1, 2, and 3 in the following form:

1000 T

8 liNe

9

Here, this equation shows that the thickness of the double layer and

the zeta potential vary with electrolyte concentration, even though the

surface charge density does not vary.

Besides the effect of dispersion and swelling on the permea-

bility of a soil in the presence of exchangeable sodium, many investi-

gators studied the effect of rainfall under various conditions on the

permeability of soils.

-Law (26) reported, "It was found that as the drop size in-

creased, the infiltration rate decreased by as much as 7070tT

Brost and Woodburn (3) reported similar results when they elim-

mated most of the drop-impact with straw supported an inch above the

10

soil. Many investigators have pointed out that mulches and crop

canopies which protect the surface of the soil against raindrop impact

will help to preserve its infiltration capacity.

Ellison (9) has pointed out that raindrop impacts break down

the aggregates, splash the soil particles to make them muddy, and cause

puddling and compaction. Each one of these actions tends to destroy

the infiltration capacity of the soil. -

Duely (6) concluded from studies in Nebraska that surface water

seal developed under rainfall, and it was the most outstanding factor

affecting infiltration. Twenty-nine infiltration experiments were com-

pleted at Coshocton for purposes of studying the effect of drop size,

drop velocity, and intensity on the infiltration capacity of four soils.

These experiments showed that a variation in either drop size or drop

velocity will cause a change in the infiltration capacity of the soil.

Changes in drop velocity have the greatest effect, changes in drop size

are second, and changes in rainfall intensity have the least effect.

It was also found that the velocity of surface flow did not affect the

rates of infiltration.

Duely (7) showed that a thin compact layer which forms over

bare soils during rains has had a greater effect on intake of water

than has had the type, slope, moisture content or profile characteris-

tics. For nigh intake of water by a soil, the immediate surface should

be in a condition to absorb water rapidly.

Munns and Lassen (36) explained that compaction of the soil may

increase runoff. A common cause of compaction is falling raindrops

11

striking exposed soil, creating mud water which partially clogs the

surface pores.

Ellison (9) showed that splash caused by raindrop impact is

harmful to the infiltration capacity of the soil and that a principal

objective of the conservationist must be to prevent the dispersion of

the clods and aggregates and the splash of the soils by raindrop impact.

Izzard and Augustine (19) indicated that raindrops falling on

shallow surface flow may retard the translational velocities. However,

experiments have shovm that this retardation does not reduce the amount

of soil transported by the flow.

Lowdeunilk (27) observed the beneficial effect of forest litter

and attributed the slow rate of intake by the bare land to a plugging

of the pores by the suspended particles settling into them from the

muddy runoff water. The increased runoff from bare land as compared

with cropland has been explained in general statements as being due to

the beating effect of rain.

C. B. Cluff and G. R. Dutt (5) indicated that watershed treat-

ment with sodium chloride may provide additional water at a low price

for irrigation. To test the NaCl treatment in Arizona, 10 pans were

filled with three different soil types and subjected to normal rain-

fall. Three pans were treated to attain a 15 percent exchangeable

sodium percentage in the surface inch of soil. One pan was treated

with a double amount of sodium salt in order to achieve a higher per-

centage. Water yields ranged from zero on the untreated soil to 497

water yield from the heavily treated soils. Later, these results were

12

tested at Atterbury Experimental Watershed near Tucson, Arizona. It

was found that NaC1 treatment increased runoff from winter storms about

25 times. The quality of the water was also tested, and it was found

that water from the treated plot contained less than 200 ppm dissolved

salt.

THEORY

Various investigations showed that the rate of infiltration is

a variable factor, It is changed with alteration in soil structure,

temperature of the air, moisture content of the soil, and the degree of

biological activity within the soil profile, Despite these factors, it

is recognized that infiltration of water into different soils is asso-

dated with the physical characteristics of the soils and their miner-

alogy. Earlier workers showed that the infiltration in a certain soil

is greatly affected in the presence of exchangeable sodium ions. The

infiltration rate (31) is decreased with the amount of exchangeable

sodium ions, especially when the soils contain 2:1 type of clay, while

on the other hand soils high in 1:1 type of clay are virtually insensi-

tive to exchangeable sodium ions,

The infiltration rate (32) in a soil is decreased due to two

processes which take place in the soil:

Swelling

Dispersion and translocation of the clay particles.

Swelling and dispersion occur simultaneously (12, 35) which is

followed by the subsequent translocation of the dispersed particles.

Due to the translocation of these dispersed particles, the conducting

pores in the soil become clogged, resulting in a decrease in the infil-

tration rate of water In the soil.

From recent work concerning clay it could be concluded (17, 33, 34,

and 35) that the runoff in sandy soils is a function of the mineralogy

13

14

of the clay and the amount of exchangeable sodium present in the soils.

With this in mind, the following research was conducted.

METHODS AND MATERIALS

Diffraction patterns of all the clay samples were obtained in

order to know the impurities which are present in these samples, The

sand was repeatedly leached with distilled water, so that all of the

soluble ions present in the sand were removed, All of the clay samples

were saturated with 2 N CaCl2 solution in the form of approximately 2

percent suspension of clay. The suspensions were mechanically stirred

for one hour four separate times at regular intervals of four hours,

Then the suspensions were equilibrated for 24 hours, washed repeatedly

with distilled water until the conductivity of the supernatant became

0.2 millimoh/cm, and dried at 80°C, The sand and the calcium saturated

clays were then mixed in the ratio of 9:1, These mixtures were consid-

ered to be artificial sandy soils for the present investigation's pur-

pose and were called bentonitic, kaolinitic, and illitic soils,

depending upon the clay mineral which was present in the soil.

Cation exchange capacity, exchangeable ions, and soluble ions

were determined according to the methods listed under Analytical Pro-

cedures.

A computer program (Appendix) developed by 0, R. Dutt was used,

in order to know the amount of sodium chloride needed to bring the sur-

face inch of soil to 8, 15, and 30 percent exchangeable sodium, The

calculated amount of NaCl was mixed with the artificial soils, and the

treated artificial soils thus obtained were placed over sand in the

containers. These containers were then subjected to artificial

15

16

rainfall for a period of one hour. The intensity of the rain was main-

tamed at 4,34 cm per hour,

Infrared lamps were used for drying the soil columns after

each rain treatment. The distance was between lamps and the top of the

soil columns was kept at about 16 cm. Runoff was collected in a beaker

and measured volumetrically with a graduated cylinder. Finally, a

saturated paste extract was prepared (46) and analyzed for Ca, Mg,

+and Na

Materials

Three clays were used for treating sand in combination with

NaC1. They were Wyoming Bentonite, Georgia Kaolinite, and Illinois

Illite. Pure, colloidal, gel-forming bentonite was obtained from

Magnet Cove Barium Corporation, Greybull, Wyoming, and Houston, Texas.

The Georgia Kaolinite used was the coLumercial grade. It was supplied

by the Georgia Kaolin Company. The Illinois Illite was supplied by

Ward's Natural Science Establishment, Inc., Rochester 3, New York.

This illite was of the same standard as that used in American Petrol-

eum Institute Clay Mineral Standard Project No. 49. Crystal white

silica sand was used in combination with various clays and sodium

chloride. This sand was supplied by Cryst-Silica Company, Oceanside,

California. Analytical sodium chloride was used which was supplied by

the J. T. Baker Chemical Company, Phillipsburg, New Jersey.

Rainfall Simulator

In order to know the effect of rainfall on artificial sandy

soils, a rainfall simulator1 was constructed. This rainfall simulator,

which is depicted in Figure 1, consists of a Mariotte flask which func-

tions as a constant head control in the top column of the rainfall

simulator. The water is passed through hypodermic needles which are

fixed in the lower part of the top column. The height of this column

is 15.75 cm. The top column is moved in the form of a circle by the

electric motor in order to provide uniform rain on the soil which is

placed in the bottom column. The container at the bottom for holding

soil is 15.24 cm. The middle column which connects the top and bottom

columns is 133.96 cm in length. All of the columns are made of plexi-

glass. The internal diameter of all of the columns is 12.70 cm. The

calibration curves for the rainfall simulator are shown in Figure 2.

Degassed distilled water was used for calibration.

17

1. The simulator was designed by Brent Cluff, who also super-vised its construction, in the Water Resources Research Center of theUniversity of Arizona, Tucson.

Motorized Revolving Rod

Beaker forCollectingRunoff

Figure 1. Rainfall Simulator

--

rrr,1n1

L

48.26 cm

Siphon

Constant:

Hydraulic Head -

HypodermicNeedles

18 c

The Mariotte Flaskfor Constant HeadControl

Clear Plastic

Wooden Frame

Pan for Holding Sandand Artificial Soil

Bubble Tube ----

()

CO

18

5.0

-2 5

0.0 L__

y = 0.48x -. 0.43

= ± .24

(Hydraulic Head in cm)Figure 2. Calibration of Rainfall Simulator

10

19

ANALYTICAL PROCEDURES

Preparation of Clay Suspensionfor Xray Diffraction

Ten-gram samples of each clay were dispersed in 6-mu poly-

ethylene bags in the ultrasonic bath for one hour. The dispersed

clay samples were then transferred to 250-ml polyethylene centrifuge

bottles and centrifuged at 750 rpm for 5.3 minutes (24). International

centrifuge size 2, No. El004, 3/4 H.P., was used for this purpose. The

clay samples were mounted on porous ceramic slides using a modification

of the paste method (2). The mounted clay samples were then washed

with 0.1 N HC1 and Mg (ACO)2, x-rayed, then washed with glycerine and

x-rayed again.

Diffraction patterns for the oriented samples on ceramic plates

were made using a Norelco x-ray diffraction unit with a copper K =

01.54 A, and the clay minerals were identified using the basal spacing

(20, 2).

Determination of CationExchange Capacity

The clay samples were repeatedly saturated with 1 N NH4ACO in a

centrifuge tube and washed repeatedly with 98 percent isopropylalcohol.

An estimation of the exchanged auimonia on the clay complex was made by

transferring a 10-mi dispersed clay suspension into a Kjeidahl's flask

for distillation. A parallel 10-mi clay suspension was dried in an

20

21

and the concentration of clay was determined. The cation exchange ca-

pacity was calculated as follows:

ml of H2SO4 x N of H2SO4 x 100CEC =

weight of the clay used

Exchangeable Cations

Exchangeable cations were determined according to U. S. Depart-

ment of Agriculture Handbook No. 60.

Determination of Soluble Saltsin Artificial Soil

Saturated paste extract was prepared (47) either with 1:1 or

1:2 ratio, depending upon the physical character of the soil. The ex-

tract was then analyzed.

Calcium and Magnesium Determination

Cy DTA of .01 N was titrated against 10 ml of the soil extract

using NH4C1-NH4OH buffer and methyl red and calmagite as indicators.

The calculation follows:

-H- 4-FCa + Mg meq./L = meq.of .01 N Cy DTA used (41).

Calcium Determination

Cy DTA of .01 N was titrated against 10 ml of soil extract with

KOH buffer and calcein indicator. The calculation follows:

ml of Ca4± titration = meq of Ca4±

-H- -H- -H- -H-,ml of (Ca + Mg - ml of Ca = meq. of Mg 4l

22

Carbonate and Bicarbonate

Fifty ml of the extract was titrated with standard acid, using

a phenolphtholein indicator. For bicarbonatebromocresol green indi-

cator was used (41).

ml N/b H2SO4 x 12 = ppm CO3ppm CO3

- meq. CO3

(total ml N/50 F12SO4 - 2CO3 titration) 24.4 = ppm HCO3

ppm HCO3- me.HCO3

61

ysis of Runoff Water for Sodium

Atomic absorption spectrophotometer was used for the determina-

tion of sodium in runoff water (13).

Conductivity of Runoff Water

Conductivity Bridge Model R C l6B2 was used in order to measure

the conductivity of the runoff water (47).

Sodium Determination

Beckman D U Spectrophotometer technique was used for sodium

determination (47).

Chloride Determination

Twenty-five ml of the extract was titrated with AgNO3 using

K2CrO4 as an indicator (41). The calculation follows:

ml of AgNO3 solution used x 40 = ppm x Cl

ppm of Cl= meq. of chloride

35.46

Ten ml of the extract was titrated with barium chloride (.43 gm

BaC12/L of water) using ethyl alcoholic thorin indicator (41). The

calculation follows:

ml of BaC12 used x 20 SO4 ppm

SO4 ppm

48meq. 504

DeteLlitination of Cla in Runoff

DeteLLuination of clay in runoff water was obtained by finding

the difference between the weight of a suspension and the weight of

clay after baking to dryness at 110° centigrade.

Determination of Moisture inArtificial Soils

Saturated paste extract was prepared as described in U. S. D. A.

Handbook No. 60, and percent moisture was determined.

Estimation of Exchan eable SodiumPercent From Soluble Cations

Saturated paste extract was prepared (47) and determined the

calcium, magnesium, and sodium ion concentrations in the saturated

extract. The calculations are as follows:

23

7 ESP100 (-0.0126 + 0.01475x)1 + (-0.0126 + 0.01475x)

where x is equal to the sodium-adsorption ratio.

+Na

=

2

where Na+, Ca, and Mg refer to the concentrations of the designated

cations expressed in milliequivalents per liter.

A nomogram, which relates soluble sodium and soluble calcium

plus magnesium concentrations to the SAR, is given in Figure 27 in the

U. S. D. A. Handbook No, 60. Also included in the nomogram is a scale

for estimating the corresponding ESP percent based on a linear equation

given in connection with Figure 9 (Chapter 2). For accurate calcula-

tion of ESP, a computer program was used as given in the Appendix.

24

RESULTS AND DISCUSSION

Calibration of Rainfall Simulator

In order to calibrate the rainfall simulator, rainfall in

centimeters versus hydraulic head in centimeters was plotted on graph

paper. It was observed that the data were very scattered due to sever-

al variable factors concerning the simulator. Using the method of

least squares, a straight line was calculated and is shown in Figure 2.

The standard deviation was calculated to be ± .24 from the ex-

perimental observation. This deviation in rainfall could be attributed

to the following causes. During calibration, gas is absorbed in water

which affects the flow of water drops through the hypodeLlihic needles.

After every hour, the simulator was adjusted for hydraulic head. At

this stage it was difficult to judge whether all of the hypodermic

needles were functioning properly or not.

X-ray Diffraction of Cla s

X-ray diffraction analyses were perfotiued to identify possible

impurities in the clays which were used in this work. X-ray diffraction

patterns were obtained following two treatments: Mg saturation and

++air dried, and Mg saturation and glycerol solvation. Figure 3 shows

0a peak of 14.73 A corresponding to montmorillonite when the bentonite

sample was treated with magnesium and air dried. This is the first

order basal reflection (001) spacing for montmorillonite. When the

0 0bentonite was treated with magnesium and glycerol, 17.70 A and 10.00 A

25

03.35 A

07.15 A

014.73 A

010.04 A

26

Figure 3. X-Ray Diffraction of Bentonite, Kaolinite, and IlliteSaturated With Magnesium and Air Dried.

27

peaks corresponding to montmorillonite and illite, respectively, were

noted (Figure 4). It was concluded that the bentonite has illite as an

impurity.

Kaolinite was saturated with magnesium and air dried; three

0 0 0peaks of 7.15 A, 4.09 A, and 3.59 A were observed. The prominent first

0 0and second order basal reflection at 7.15 A and 3.59 A, respectively,

are du to kaolinite (Figure 3). The 4.05 peak due to -Cristobalite

is present in the ceramic tile. Peaks at 10.00 and 7.15 were ob-

served when the il1lite was treated with and solvated with glycerol

0 0(Figure 3). The lQ.00 A peak is due to illite and the 7.15 A peak in-

dicates the presence of kaolinite as an impurity.

Cation ExcheCfColloidal Clay

Routine chemical methods were used to determine the cation ex-

change capacity of the clay samples, but none of them was found satis-

factory due to the dispersion effect of sodium, which was present in

the bentonite clay samples. A large amount of clay was lost during

washing and centrifuging the clay samples. The sticky nature of

bentonite was very inconvenient in the process of determining its CEC

by the standard method (47). Attempts were made to use the standard

method, but it was found difficult to duplicate the results. Therefore,

an indirect method was used for CEC determination in order to overcome

these difficulties.

Clay suspensions were saturated with ammonia acetate, and then

the amount of aulihionia on the clay complex was determined. This

17.70

Figure 4. X-Ray Diffraction of BentOnite and Illite SaturatedWith Magnesium Glycerol Solvated

29

exchanged ammonia on the clay complex gave a measure of cation exchange

capacity of clay. The cation exchange and the exchangeable ion of

these clays are shown in Table 1.

Cation Exehang a.pacity, Soluble IonsjIoistureEquivalent of Artificial Sandy Soils

Table 2 shows the texture cation exchange capacity, soluble

ions, and moisture equivalent of the artificial sandy soils.

Exchan:eable Sodium Percentae andIts Effect on Runoff

Three artificial soils containing 0, 8, 15, or 30 percent ex-

changeable sodium ions were subjected to artificial rainfall. During

the application of water, the hydraulic head on the simulator was kept

constant (i.e., the height of water in rainfall simulator was 11.20 cm).

Table 3 shows the average runoff in ml, electrical conductivity

in mmohs/cm at 25°C, concentration of sodium ions in ppm in runoff

water, and clay transferred in grams with the runoff water. It may be

seen from this table that the runoff is increased when the exchangeable

sodium percentage in the soil is increased (Figure 5).

It is also noted that at any given sodium percentage the in-

crease in runoff from bentonitic soil is higher than that of the kaolin-

itic and illitic soils. This may be explained on the basis of interlayer

swelling of bentonite. It is known (1) that the swelling of clay is de-

pendent upon its crystal structure. In the case of 2:1 expanding type

of clay mineral, the bonds which hold the individual sheet of clay are

much weaker than the non-expanding type clay minerals. In the case

Name

Table 1.

Exchangeable Ions and Cation Exchange Capacity of Clays

Cation Exchange

Exchangeable Cation (meq./L)

Capacity (meq./L)

Ca

Mg

KNa

Bentonite

93.00

14.65

0.81

1.35

41.25

Kaolinite

14.40

6.14

0.04

T0.02

Illite

20.40

11.75

1.33

0.01

2.51

Table 2.

Exchange Capacity, Soluble Ions, and Moisture Equivalent in Artificial Soils

Texture

Cation

Paste

Soluble Ions (meq./L)

Mois ture

Soils

Sand

Clay

Exchange

Soil:Water

Cations

Anions

70

Ca

Mg

Na

Cl

SO4

CO3

HCO3

'70

70Capacity

Ratio

Bentonite

90

10

9.30

1:2

4.18

0.62

0.40

4.72

1.25

1.28

85

Kaolinite

90

10

1.44

1:2

0.18

--

0.20

0.91

0.08

0.64

40

Illite

90

10

2.04

1:2

4.74

0.76

0.26

4.98

1.46

1.13

30

Table 3.

Average Runoff, Electrical Conductivity, Sodium Concentration, and Amount

of Clay Eroded

Soils

ESP in

Soils

Average

Runoff

in ml

Average3

EC x 10

at 25°C

Average Na

Concentration

ppm

Average Gms

of Clay

Transferred

Bentonitic

untreated

967 ±30

0.047

2.24

0.385

Soil

81392±30

0.062

6.14

0.605

15

1505

0.063

10.62

0.707

30

2043 ±20

0.209

11.97

0.788

Kaolinitic

untreated

442±13

0.032

5.72

0.177

Soil

8626±12

0.035

4.19

0.397

15

1331±5

0.032

3.38

0.397

30

1390±20

0.209

6.33

0.423

Illitic

untreated

346±12

0.075

2.11

0.466

Soil

8596±22

0.059

3.10

1.098

15

801±137

0.041

5.07

0.065

30

838±153

0.337

5.55

0.071

2000

1500

1000 50

0

08

L5

Kaol1fht

SoIlS

Illitic Soils

300

(ESP)

Figure

5.Runoff Versus Exchangeable Sodium Percentage in Soils

34

of bentonite the attraction arises from the Vander Waals forces between

sheet system, and of these of kaolinite the attraction arises from hy-

drogen bond, Hydrogen bonds are much stronger than Vander Waals forces.

Thus, bentonite swells spontaneously when mixed with water, while

kaolinite does not. As the degree of hydration of bentonite is increased,

C-spacing is also increased due to water penetration in the crystal lat-

tice of the clay. In the case of kaolLriite (49), the hydration energy

of water is not sufficient to break all of the bonds between the sheets,

and thus kaolinite behaves as a non-swelling clay. Illite is an example

of 2:1 type of clay but behaves as a kaolinite-type clay mineral. The

non-swelling character of illite (49) is attributed to a specific link-

ing effect of the unit layers by the potassium ions. These ions are of

the right size to establish a 12-coordination with opposite hexagonal

oxygen rings of adjoining unit layers, being embedded in the space

created by opposite holes.

In the case of kaolinitic and illitic soils, only dispersion

occurs, which results in the partial blocking of the conductive pores,

and thus the infiltration rate is decreased.

Figure 6 shows the percent increase in runoff versus exchange-

able sodium percentage. Runoff from bentonitic soil is increased by

43.0, 55.6, and 111.3 percent when the exchangeable sodium percentage

is changed from untreated bentonitic soil to 8, 15, and 30 percent, re-

spectively. Similarly, under identical conditions, the runoff is in-

creased by 41.6, 201.0, and 214.0; and by 72.2, 131.5, and 143.4 percent,

in the case of the kaolinitic and illitic soils, respectively. It is

200

'1-1 0

150

0 0) 0 0

100 50

15

Figure 6.

Percent Increase in Runoff Versus ESP

(ESP)

Kaoliflitic Soil

Soil o-

30

36

noted from these results that the percent change in infiltration due to

sodium in these clays follows the order shown below:

kaolinite> illite bentonite.

It could also be concluded from Table 4 (see page 39) that if a soil

contains predominantly kaolinite and illite, less sodium would be re-

quired to raise the sodium percentage as compared to the soil containing

predominantly bentonite.

The overall increase in runoff from these three types of clay

follows the order shown below:

bentonite> i11ite kaolinite.

Bentonite, kaolinite, and illite are clay minerals and are

found generally in abundance in soils. Results for these clay minerals

would reflect the behavior of soils in the fields Thus, it could be

concluded from the entire research that the soils in the field may be

treated with sodium chloride in such a way that they contain from 8 to

15 percent exchangeable sodium in order to achieve maximum runoff. It

may be pointed out that a soil is saline if the electrical conductivity

of the saturation extract is in excess of 4 mmohs/cm, but the ESP is

less than 15 (48). If the electrical conductivity of the saturation

extract is greater than 4 mmohs/cm and the ESP exceeds 15, then the soil

is saline and alkaline. Thus Table 3 shows that the soil would not be

adversely affected for agricultural purposes with such treatments.

It was concluded from this investigation that if the artificial

soils used in this work contained from 8 to 15 percent exchangeable

sodium, then maximum runoff would be achieved without producing any

37

harmful effect to the soil, and the quality of the water would be satis-

factory for irrigation purposes.

Runoff Water

The electrical conductivity of runoff water (Table 3) ranges

from 0.032 mmoh/cm (untreated bentonitic soil) to 0.337 mmoh/cm (illitic

soil containing 30 percent exchangeable sodium). The sodium concentra-

tion varies from 2.11 ppm (untreated illitic soil) to 11.97 ppm (benton-

itic soil containing 30 percent exchangeable sodium). Taking into

consideration the maximum concentration of salt present in runoff water,

the water class, with respect to salinity, was evaluated by means of

electrical conductivity, and the sodium hazard by means of SAR. It was

found to be C2S1 (46). This shows that the water is of medium salinity

and contains low sodium. Medium salinity water C2 can be used if a mod-

erate amount of leaching occurs. Plants with moderate salt tolerance

can be grown in most cases without special pre-actions for salinity

control.

Low-sodium water S1 can be used for irrigation on almost all

soils with little danger of the development of harmful levels of ex-

changeable sodium. However, sodiumsensitive crops may accumulate

injurious concentrations of sodium. Since this water class was evalu-

ated on the basis of maximum salt concentration in runoff water, it

could therefore be concluded that the overall quality of runoff water

would be quite satisfactory for irrigation purposes.

Exchangeable Sodium Percentage andSodium Adsorption Ratio in the Soils

Table 4 shows the amount of salt (needed by the soil to have

required ESP), predicted ESP, experimental exchangeable sodium percent-

age, and the sodium adsorption ratio.

It is noted from this table that the experimental values of ex-

changeable sodium percentage are lower than the theoretical values. The

low experimental values could be expected, due to the following factors:

increase in moisture content

erosion.

The estimation of exchangeable sodium percent was done in 2:1 soil

paste; therefore, the low exchangeable sodium percent is expected.

Raindrop impact disturbs the soil due to its beating effect which sub-

sequently helps in erosion and downward movement of the clay with rain-

water. Most of the sodium ions are either exchanged on the clay surface

or adsorbed on it; thus the amount of exchangeable sodium would also be

decreased in the soil due to the loss of clay.

38

Table 4.

Theoretical, Computer Predicted, and Experimental ESP and SAR

Soils

Theoretical

ESP

Lbs. of Sodium

Chloride Required

to Treat One Acre

of Land to Have

Theoretical ESP

Gms. of Sodium

Chloride Required

to Treat 350 Gms.

of Soil to Have

Theoretical ESP

ESP

Pre sent

in the

Soil

Pre-

dicted

E SF

Average

Experi-

mental

ESP

Average

SAR

Bentonitic

8281.90

0.296

0.40

4.80

6.45

4.67

Soil

15

619.10

0.651

0.40

9.90

9.85

7.41

30

1578.50

1.659

0.40

21.70

18.36

15.24

Kaolinitic

860.00

0.063

1.00

7.90

7.51

5.50

Soil

15

154.20

0.162

1.00

14.00

8.35

5.78

30

449.70

0.473

1.00

29.90

21.05

18.46

Illitic

8128.50

0.134

0.20

1.50

1.09

0.75

Soil

15

274.00

0.288

0.20

3.20

3.30

2.33

30

681.40

0.714

0.20

7.80

6.67

4.87

SUMMARY AND CONCLUSIONS

Bentonitic, kaolinitic, and illitic clays were saturated with

calcium chloride and then mixed with sand in the ratio of 1:9 to simu

late artificial soils. Portions of each of the artificial sandy soils

were treated with sodium chloride to achieve 8, 15, and 30 percent ex-

changeable sodium. Each of these treated artificial soils were then

placed in a container and subjected to artificial rainfall. They were

repeatedly dried and again subjected to artificial rainfall until five

measurements were made. The runoff from each artificial soil was

collected, measured, and analyzed. It was found that the runoff was

increased with exchangeable sodium present in the soil. A sharp in-

crease in runoff was observed in all of the artificial soils when the

exchangeable sodium was raised from 8 to 15 percent in the soils. It

was also noted that the runoff was increased in the following way with

these soils:

illite< kaolinite (bentonite.

The experimental values for the exchangeable sodium percentage

were found to be lower than the calculated values, due to increased

moisture content, downward movement of clay, and its erosion with run-

off water.

The electrical conductivity of runoff water ranges from 0.032

rnmoh/cm to 0,337 mmoh/cm, and the sodium concentration ranges from

40

41

0.09 rneq./L to 0.52 meq./L. The irrigation water class with respect to

salinity and sodium hazards was evaluated and found to be C2S1 (47).

This shows that the water is of medium salinity and contains low

sodium.

It was concluded from this investigation that if artificial

soils containing any of the above clays and containing 8 to 15 percent

exchangeable sodium were used maximum runoff would occur and the

quality of runoff water would remain satisfactory for irrigation.

Since these clays are found in abundance in soil, we could, therefore,

use these results to apply to soils in the field.

ooisaasa DdsJ=cvs

uvs-cL?Io O+=dsa ((z/(oNvvD))Jis)/sosws

S'ODH'0S''S0S'OWV'VD'1O LMIId ( '11

/bai'i i/bw 'i/bw '-i/öz i/baw 'i/bw H0L)1vWdO1 zoc

ZOC 1NId (nisiow

ODH 'OS 'rn VN ON YD H0L)JvWaOa OOC

OOC 1NflM (9x'9x"z 9JX17'Z9dX'Z9JX7' 9,IX17'Z9XZOH1)1VWIO,ff 1OO

( 'cvgro,i SISA'WNY IIosHLTxo)3vTnio ioc NVN'IO JNflId

oo=cxx (O119) ivwao 1

1'ddS'O3H"IVD''S'1 GVfl1

(oiic) ivwio, o 0S'D'SOS'DNV'V3'0 aai

oo=aii cz cz'66 (c'!io),I

(cv9T)ivwo, WVN'O UYi

I =IC 00=iVD 0001

(Tm) 1VW'dOJ 01 01 JNI1d

(91)J\IVM NOISNTIQ N0ILV)III1VS 1V lfL1SION 1N3id = 3

Rf1i SVM LDVL1X H3IHM LV }IflLSI0N = Il 3 OVINDI21 NflIGOS 'ISYONVH3Xa = ddS

'diLI1 / bIN NI '3NO3 LVN0VDI = O3I-I 3 'iios (oo) Sfl0VDTV3N0N io (o1) snowiv =

WVHO / bI NI AJJDVdV3 2ONVHDXJ NOLLV3 = 3 32ILI'I / bN NI DN0D LV1flS = OS 3 1Th1I'I / ÔW NI 3NO3 Iard01H3 = D 3

ULLI'I/bfH NI 3NO3 NflIGOS = SOS 3 HaLT i/bi NI 3NO3 WflISNOVN OHV 3

Hm1rI/bN NI 3NO3 NflIDTcTD = YD 3 LNW1VHL QHSHIVM 'IDYN 3

)rVLLVH)1

V NVHOOad

XIUNadCTV

SA5=SA5/1000.RA=CA/(ANG*. 625)

C5=ZE/(RA+1.)E5=ZE-05

E5=E5/2000.C5=C5/2000.

SO=SO/2000.CL=CL/1000.s0s=s0s/1000.HCO3=HCO3/1000.D=. 623

CA=CA/2000.DA=. 608

ANG=ANG/2000.U=SQRT( 2 o*( CA+AMG+S0)+O 5*( SOS+CL+HCO3))

IF(CAL) 602,602,603602 IK=1

ZE=2.OE-8GO TO 604

603 IK=2ZE=(CA*HCO3**2*EXP (_2.341*U/(1.±U)))

604 A=2 .*CA*B 1/B

G=2.*SO*B1/BF=2 *j4C*B 1/B

H=2 .*CL*B1/B

S=2.*SOS*B1/BHCO3=2 . kHCO3*B1/B

B=1.E5*2./BET=E5

CT=C5SAT=Sk5XXT=XX5

24 A1=AIF(XXT)4,4, 26

4 U=SQRT(2.O*(A+F+G)X0.5*(S+H11CO3))AA=EXP (-9 .366*U/(1.0+U))IF(2.4E_5_A*G*AA)26, 18,18

26 X=O.OU=SQRT( 2. 0*(A+F+C)±0 . 5*(S+I-I+HCO3))

BB=A+GEX=(9 .366*U)/(1.0+U)CC=A*G-(2 . 4E5)*EXP (Ex)

R=SQRT(BBBB-4. o*cc)x=(-BB+R)/2 .0

CAS1=4.897E-3-CASODEL=B*XXT- CAS 1

IF(DEL-X)27, 28,28

27 X=XXT*BXXT=0.OCAS1=O.O

43

1717

z-1VS=1VS zcc zIc'olc'olc(v)aI

zI+v=v :s

r'9'8 (ioo-(zzz)sv)aI zz+z=z z/zzzzz zzzlzz=zz

(au+z(O z+z(crnO +zvvO)))=zzZ 18

ssva;'-vG- xavLVSLVS= (s+O z )s vciva-O z+( ivs+vO 17)xivs=aa s.&s.'vava-(s;&O z±ia) vava-'O 17( vS+v)XIO l7=3

(svava+1VERO z+x)-'.-o qvci-vaO

((n-i-oI)/(nP7cz-)) dX=X c

Z=TZ 01/]2=Z O17

c o o

z=_[ z O1/1VS=Z ZO17

oil'oYzot'(L-1vs)aI 17017

z=ri o o8'c1c'o8(J.vs)JI 191

08'181'02 (s) ii

y=zv 9/1 SYD 1XX=LXX

ISVD+OSVD=OSVD 9/X 1XX=1XX

x+o= X+v=v 9Z

1717 01 O) TX-D=O 1x-v=v

IX+OSVD=OsVD L (vvoz)/((xxxx)aibs-sq-)=ix 9c

L 01 0 oo=ix cc

9'c'c (xxxx),ai

DDVV;0 l79999rzXXXX OSVD-i16 l7-V;'.VV=DD

(ov+vv-j--i6l7)-=88 L ((n+ 1/n99 6-) clxa=vv

((oDn Fn+s)c ox(--i-y)o° z )1Iös=n

x±v=v

L'ill7'ilil (osYD) I I L'1'T (v) Ti 9 9'1'I (o) 1I 91

551 ET=ET+Z550 S=S±2.*B*Z510 A=A-B*Z

z=-zl

GO TO 81

512 S=S-2.*B*ZIF (5) 550,550,513

513 ET=ET-Z

IF (ET)551,551,514514 SAT=SAT±2 . 0*Z

IF (SAT) 552,552,515515 A3=A

BB=A+B* ( CT+D*ET ) +D*F

AA=B*(1 . o-D)

CC=(A*CTDF*ET)R=SQRT(BB*BB4 . 0*AA*CC)

Y=(-BB+R)/(2.o*AA)A=A+B*YF=F-B*YET=ET-YCT=CT+YA4=AGO TO (600,6o1),IK

601 AA=4,OBB=4 . *HCO3-FA

CC=HCO3**2+4 .

DD=A*HCO3**a-ZEEXP (2. 341*U/(1 .+U))

IF(HCO3-A)61, 61,62

61 Z=-HCO3/4.GO TO 650

62 Z=-A/2.650 Z1=Z63 ZZ=- ( ( (AA*Z+BB )*Z+CC)*Z+DD)

zzz=((3 .O*AA*Z+2.0*BB)*Z+CC)zz=zz/zzzzzz=zz/zz=z+zz

IF(ABS(ZZZ)-.001) 64,64,63

64 A=A+ZHCO3=HCO3+2 .

IF(HCO3)752, 752, 651

752 HCO3=HCO3-2.ZA=A-Zz=-z1

GO TO 63651 IF(A) 752,752,753753 CAL=CAL-Z600 ZX=(CA*ECO3*2*EXP (-2. 341U/(1 .+ufl)

45

46

IF(DEL+1.OE-5)24,48,4848 IF(DEL-1.OE-5)49,49,2449 DEL=A-A2

IF(DEL+1.OE-5)24, 50,5050 IF(DEL-1.OE-5)51,51,2451 DEL=A-A3

IF(DEL+1.0E.5)24,52,5252 IF(DEL-1.OE-5)8,8,248 DELA-A4

IF(DEL+1 .OE-5) 24,66,66

66 IF(DEL-1.OE-5)67,67,2467 GO TO (400,4o1),JI

400 ESPL=100.*SAT/(2.*CT+2.*ET+SAT)IF(ESPP-ESP1-. 1)201, 201, 200

200 DELS=(ESPP-ESP1)*EC*B/100.TRT=TRT+DELS/1000.S=S+DELS/1000.H=H+DELS/1000.GO TO 24

201 TRT=TRT*1 .948E7/B

PRINT 2O2,ESP202 FOBMAT(3X56HTHE EXCHANGEABLE SODIUM PERCENTAGE PRESENT IN THE

SOIL 1ISF5.1,55H. THE POUNDS OF NACL REQUIRED TO TREAT ONE ACREOF LAND)PRINT 2O21,TRT,ESPP

2021 FOBNAT(1X2HISF6.1,56H. WITH THIS TREATMENT IT IS ESTIMATED THATTHERE WILL BEF5.1,48HPERCENT EXCHANGEABLE SODIUM IN THE SURFACE

INCH. 2)B=B/(1 .E5*2)

A=A*B/B 1

G=G*B/B 1

F=F*B/B 1

H=H*B/B 1

S=S*B/B 1

HCO3=HCO3B/B 1

B=1.5E5*a/B1JI=2GO TO 24

401 ESP1OO.*SAT/(2,*CT+2,*ET+T)PRINT 500,ESP

500 F0NAT(1X52HTHE ESP FROM A SATURATION EXTRACT IS ESTIMATED TO BE

1F5 .1)

CAL=CAL-1 .0

PRINT 1001,ZE,CAL1001 FORMAT(1HO2XE1O.3)

GO TO 100099 STOP

END

LITERATURE CITED

Alexander, A. E., and Johnson, P. Colloid Science, Oxford TJniver-

sity Press. 1947.

Black, C. A. Methods of soils analyses, Agronomy No. 9, Part 1,American Society of Agronomy, Inc., Madison, Wisconsin, U.S.A.1965.

Brost, H. L., and Woodburn, Russel. Effect of mulches and surfaceconditions on the water relation and erosion of Muskingum soil.U.S.D.A. Tech. Bull. No. 825. July 1942.

Browing, C. M. Change in erodibility of soil brought by the organic

matter. Soil Sd. Soc. of Amer. Proc. 2:85-96. 1937.

Cluff, C. Brent, and Dutt, C. R, Using salt to increase irrigation

water. Progressive Agriculture in Arizona, Vols. 3, 12, and 13.

1966.

Duely, F. L. Effect of soil type, slope and surface conditions on

intake of water. Nebr. Agric. Expt. Sta. Bull. No. 112. (Original

not seen.) 1939.

Duely, F. L. Surface factors affecting the rate of intake of water

by soil. Soil Sci. Soc. Amer. Proc. 4:60-64. 1939.

Bear, Firman E. Chemistry of the Soil. Reinhold Publishing Cor-

poration, New York. 1965.

Ellison, W. D. Some effect of raindrops and surface flow on soil

erosion and infiltration. Trans. Amer. Geophys. Union 26:415-430.

1945.

Ellison, W. D.,and Salter, C. S. Factors that affect surface seal-

ing and infiltration of exposed soil surface. Agric. Eng. 26:156-

157, 162. 1945.

Emerson, W. W. The swelling of sodium montmorillonite due to water

absorption. Australian J. Soil Res. 1:129-143. 1963.

Firman, M,, and Bodman, G. B. Permeability measurement on disturbed

soil samples. Soil Sci. 58:337. 1944.

47

Harris, J. S. Effect of variation in moisture content on certainproperties and on the growth of wheat. Cornell University Agric.Expt. Sta. Bull. No. 352. pp. 801-868. 1914.

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