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 Requirements For 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 requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for peLuhission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarIn all other instances, however, permission must be obtained ship. from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: GORDON R, DUTT Assoc. Professor of Agricultural Chemistry and Soils Date ACKNOWLEDGMENTS The author wishes to express his gratitude to Dr. Cordon R. Dutt for his guidance, encouragement, and helpful discussion and review 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 Resources Research Act of 1964, 111 TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS vi LIST OF TABLES vii ABSTRACT INTRODUCTION viii 1 . LITERATURE REVIEW 3 THEORY 13 METHODS AND MATERIALS 15 Materials Rainfall Simulator 16 17 ANALYTICAL PROCEDURES 20 Preparation of Clay Suspension for X-ray Diffraction Determination of Cation Exchange Capacity Exchangeable Cations Determination of Soluble Salts in Artificial Soil Calcium and Magnesium Determination Calcium Determination Carbonate and Bicarbonate Analysis of Runoff Water for Sodium Conductivity of Runoff Water Sodium Determination Chloride Determination Sulphate Determination of Clay in Runoff Determination of Moisture in Artificial Soils Estimation of Exchangeable Sodium Percent From Soluble Cations RESULTS AND DISCUSSION . . . 20 20 21 21 21 21 22 22 22 22 22 23 23 23 23 25 Calibration of Rainfall Simulator X-ray Diffraction of Clays Cation Exchange Capacity of Colloidal Clay Cation Exchange Capacity, Soluble Ions, and Moisture Equivalent of Artificial Sandy Soils iv 25 25 27 29 V TABLE OF CONTENTS Continued Page Exchangeable Sodium Percentage and Its Effect on Runoff Quality of Runoff Water Exchangeable Sodium Percentage and Sodium Adsorption Ratio in the Soils . 29 37 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 Illite Saturated With Magnesium and Air Dried 26 X-Ray Diffraction of Bentonite and Illite Saturated With Magnesium Glycerol Solvated 28 Runoff Versus Exchangeable Sodium Percentage in Soils 33 Percent Increase in Runoff Versus ESP 35 vi LIST OF TABLES Page Table Exchangeable Ions and Cation Exchange Capacity of Clays 30 Exchange Capacity, Soluble Ions, and Moisture Equivalent in Artificial Soils 31 Average Runoff, Electrical Conductivity, Sodium Concentration, and Amount of Clay Eroded 32 Theoretical, Computer Predicted, and Experimental ESP 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 kaolinitic 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 artificial 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 exceeds the present available supply and does not properly satisfy agricultural, 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 runoff 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 2 The purpose of the present work is to study the type, placement, and amount of clay in sandy soils and the ESP that must be present in order to obtain maximum runoff. 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 particle arrangement on the permeability of sand. Ellison and Salter (10) attributed the greater part of the difference between infiltration capacities 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 permeability 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 maintained. 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 4 soil containing predominantly montmorillonite clay. Both soils showed a very similar initial permeability, but due to the swelling of montmorillonitic clay, permeability decreased more rapidly on the montmorillonitic 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 fertilizer 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 content 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 flocculating 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 5 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 infiltration 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. 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, In 6 When 3 or 4 percent of the their swelling properties were increased, Kashmir bentonite was mixed with sand, the rate of percolation was reduced to 0.12 or 0.05 cc of water per minute, respectively. Norrish and Quirk (38) used electrolytes to control the swelling 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-. oxide content. . -H- . 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 textured soil and those containing small amounts of expandable minerals. Harris (14) studied the effect of moisture content on the degree 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 content 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 effective 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 deflocculation with increasing rates. Johnson and Norton (21), working with extremely pure kaolinitic suspension, showed that for maximum dispersion the medium must be somewhat 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 mentioned earlier, is in agreement with the theories of Helntholtz, Gouy, and Stern (in H. Van Olphen, 39; and in Taylor and Glasstone, 43). 8 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 derived 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 composit ion. Using Maxwell, Boltzman, and Poisson's equations, Gouy obtained the following expressions: 46-lr 1000 kT 8 Ne2p i7 where 9 /1 2 = concentration of cations c z = valency of cations e = electronic charge T absolute temperature k Boltzman constant N Avogadro's Nurtiber 2, and 3 that is equivalent to In other words, - gives the thick- It is clear from equations 1, thickness of the double layer ness of the equivalent Helntholtz double layer. We can relate equations 2, and 3 in the following form: 1, 1000 T 8 liNe 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 permeability 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 characteristics. 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 rainfall. 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 percentage. 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 mineralogy. 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 insensitive 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 infiltration 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 Procedures. A computer program (Appendix) developed by 0, R. Dutt was used, in order to know the amount of sodium chloride needed to bring the surface 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. by the Georgia Kaolin Company. It was supplied 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 Petroleum Institute Clay Mineral Standard Project No. 49. Crystal white silica sand was used in combination with various clays and sodium chloride. California. This sand was supplied by Cryst-Silica Company, Oceanside, Analytical sodium chloride was used which was supplied by the J. T. Baker Chemical Company, Phillipsburg, New Jersey. 17 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 functions 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. is 15.75 cm. The height of this column 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. soil is 15.24 cm. The container at the bottom for holding The middle column which connects the top and bottom columns is 133.96 cm in length. glass. All of the columns are made of plexi- 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. The simulator was designed by Brent Cluff, who also supervised its construction, in the Water Resources Research Center of the University of Arizona, Tucson. 1. 18 Bubble Tube ---- Motorized Revolving Rod Siphon Constant: Hydraulic Head - L -- () rrr,1n1 CO Hypodermic Needles 18 c The Mariotte Flask for Constant Head Control Clear Plastic Wooden Frame Pan for Holding Sand and Artificial Soil 48.26 cm Beaker for Collecting Runoff Figure 1. Rainfall Simulator 19 y = 0.48x -. 0.43 = ± .24 5.0 -2 5 0.0 L__ 10 Figure 2. (Hydraulic Head in cm) Calibration of Rainfall Simulator ANALYTICAL PROCEDURES Preparation of Clay Suspension for Xray Diffraction Ten-gram samples of each clay were dispersed in 6-mu ethylene bags in the ultrasonic bath for one hour. poly- 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 = 0 1.54 A, and the clay minerals were identified using the basal spacing (20, 2). Determination of Cation Exchange 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 The cation exchange ca- and the concentration of clay was determined. pacity was calculated as follows: ml of H2SO4 x N of H2SO4 x 100 CEC = weight of the clay used Exchangeable Cations Exchangeable cations were determined according to U. S. Department of Agriculture Handbook No. 60. Determination of Soluble Salts in 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: Ca -H- 4-F meq./L + Mg = 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. ml of Ca4± titration -H- ml of (Ca -H- + Mg = The calculation follows: meq of Ca4± - ml of Ca -H- = meq. of Mg -H-, 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 CO3 ppm CO3 (total ml N/50 F12SO4 - 2CO3 titration) 24.4 ppm HCO3 61 - meq. CO3 = ppm HCO3 - me.HCO3 ysis of Runoff Water for Sodium Atomic absorption spectrophotometer was used for the determination 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: 23 ml of AgNO3 solution used x 40 ppm of Cl 35.46 = ppm x Cl = meq. of chloride 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 48 meq. 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 in Artificial 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 Sodium Percent 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: 24 100 (-0.0126 + 0.01475x) 1 + (-0.0126 + 0.01475x) 7 ESP 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. 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 experimental 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. At After every hour, the simulator was adjusted for hydraulic head. 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. patterns were obtained following two treatments: air dried, and Mg ++ Mg saturation and glycerol solvation. X-ray diffraction saturation and Figure 3 shows 0 a 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 0 bentonite was treated with magnesium and glycerol, 17.70 A and 10.00 A 25 26 0 14.73 A 0 7.15 A 0 10.04 A 0 3.35 A Figure 3. X-Ray Diffraction of Bentonite, Kaolinite, and Illite Saturated 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 0 peaks of 7.15 A, 4.09 A, and 3.59 A were observed. The prominent first 0 0 and second order basal reflection at 7.15 A and 3.59 A, respectively, are du to kaolinite (Figure 3). is present in the ceramic tile. The 4.05 Peaks at 10.00 served when the il1lite was treated with (Figure 3). peak due to -Cristobalite were ob- and 7.15 and solvated with glycerol 0 0 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 ExcheCf Colloidal Clay Routine chemical methods were used to determine the cation exchange 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 Saturated With 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. a.pacity, Soluble IonsjIoisture Cation Exehang Equivalent 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 and Its Effect on Runoff Three artificial soils containing 0, 8, 15, or 30 percent exchangeable 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 increase in runoff from bentonitic soil is higher than that of the kaolinitic and illitic soils. swelling of bentonite. This may be explained on the basis of interlayer 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 Cation Exchange Capacity (meq./L) 93.00 14.40 20.40 Bentonite Kaolinite Illite 11.75 6.14 14.65 Ca 1.33 0.04 0.81 0.01 T 1.35 2.51 0.02 41.25 Exchangeable Cation (meq./L) K Na Mg Exchangeable Ions and Cation Exchange Capacity of Clays Name Table 1. 90 90 90 Kaolinite Illite '70 10 10 10 70 1:2 4.98 30 1.13 1.46 0.26 0.76 4.74 2.04 40 0.64 0.08 0.91 0.20 -- 0.18 1:2 1.44 70 85 HCO3 Mois ture 1.28 1.25 4.72 4.18 1:2 9.30 0.40 0.62 Ca Soluble Ions (meq./L) Anions Cations SO4 CO3 Cl Mg Na Paste Soil:Water Ratio Cation Exchange Capacity Exchange Capacity, Soluble Ions, and Moisture Equivalent in Artificial Soils Texture Clay Sand Bentonite Soils Table 2. Illitic Soil Soil 0.071 0.337 838±153 30 5.55 0.041 801±137 15 0.065 1.098 3.10 0.059 596±22 8 5.07 0.466 2.11 0.075 346±12 untreated 0.423 6.33 0.209 1390±20 30 0.397 3.38 0.397 0.177 0.032 4.19 0.035 5.72 1331±5 626±12 0.032 0.788 15 8 442±13 11.97 0.209 2043 ±20 30 untreated 10.62 0.063 1505 15 0.707 0.605 6.14 0.062 1392±30 8 Average Gms of Clay Transferred 0.385 Average Na Concentration ppm 2.24 Average3 EC x 10 at 25°C 0.047 in ml Average Runoff 967 ±30 untreated Soils ESP in Average Runoff, Electrical Conductivity, Sodium Concentration, and Amount of Clay Eroded Kaolinitic Bentonitic Soil Soils Table 3. 500 1000 1500 2000 Figure 0 5. (ESP) L5 Runoff Versus Exchangeable Sodium Percentage in Soils 8 SoIlS Illitic Soils Kaol1fht 30 0 34 of bentonite the attraction arises from the Vander Waals forces between sheet system, and of these of kaolinite the attraction arises from hydrogen 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 lattice 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 The of 2:1 type of clay but behaves as a kaolinite-type clay mineral. non-swelling character of illite (49) is attributed to a specific linking 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 exchangeable 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, respectively. 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 0 0 0) 0 0 '1-1 50 100 150 200 Figure 6. Percent Increase in Runoff Versus ESP 15 (ESP) o- Soil Kaoliflitic Soil 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 required 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 (bentonitic 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. found to be C2S1 (46). and contains low sodium. It was This shows that the water is of medium salinity 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 exchangeable 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. 38 Exchangeable Sodium Percentage and Sodium 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 percentage, 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 subsequently helps in erosion and downward movement of the clay with rainwater. 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. Soil Illitic Soil Kaolinitic Soil Bentonitic Soils 0.473 0.134 449.70 128.50 30 0.288 0.714 274.00 681.40 15 30 8 0.162 154.20 0.063 15 60.00 1.659 1578.50 30 8 0.651 0.296 Gms. of Sodium Chloride Required to Treat 350 Gms. of Soil to Have Theoretical ESP 619.10 281.90 Lbs. of Sodium Chloride Required to Treat One Acre of Land to Have Theoretical ESP 0.20 0.20 0.20 1.00 1.00 1.00 0.40 0.40 0.40 in the Soil Pre sent ESP 7.80 3.20 1.50 29.90 14.00 7.90 21.70 9.90 4.80 E SF Predicted 6.67 3.30 1.09 21.05 8.35 7.51 18.36 9.85 6.45 Average Experimental ESP Theoretical, Computer Predicted, and Experimental ESP and SAR 15 8 ESP Theoretical Table 4. 4.87 2.33 0.75 18.46 5.78 5.50 15.24 7.41 4.67 Average SAR 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 exchangeable 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 runoff 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. XIUNadCTV NVHOOad V )rVLLVH)1 3 'IDYN 3 YD = 3 OHV QHSHIVM LNW1VHL NflIDTcTD 3NO3 NI Hm1rI/bN WflISNOVN 3NO3 NI i/bi HaLT SOS = NflIGOS 3NO3 NI ULLI'I/bfH = Iard01H3 3NO3 NI 1Th1I'I OS = LV1flS DN0D NI 32ILI'I = NOLLV3 2ONVHDXJ AJJDVdV3 NI WVHO bI = (o1) io Sfl0VDTV3N0N (oo) 'iios = LVN0VDI O3I-I '3NO3 NI 'diLI1 3 D 3 3 3 ÔW bN / / snowiv 3 ddS = 'ISYONVH3Xa Il = }IflLSI0N 3 = 3 1N3id NOISNTIQ lfL1SION bIN NflIGOS / / OVINDI21 LV H3IHM LDVL1X SVM 1V N0ILV)III1VS Rf1i (91)J\IVM JNI1d 01 01 1VW'dOJ 0001 (Tm) 00=iVD =ICI UYi WVN'O (cv9T)ivwo, (c'!io),I cz'66 cz oo=aii aai ivwio, o GVfl1 ivwao 1 0S'D'SOS'DNV'V3'0 (oiic) 1'ddS'O3H"IVD''S'1 oo=cxx JNflId (O119) NVN'IO ioc IIosHLTxo)3vTnio SISA'WNY 'cvgro,i ( 1OO 9,IX17'Z9XZOH1)1VWIO,ff 9JX17'Z9dX'Z9JX7' 1NflM OOC YD ON VN 'rn OOC H0L)JvWaOa 1NId zoc (nisiow 'OS ODH ZOC H0L)1vWdO1 'i/bw i/baw '-i/öz ( '11 LMIId (9x'9x"z S'ODH'0S''S0S'OWV'VD'1O ((z/(oNvvD))Jis)/sosws O+=dsa uvs-cL?Io DdsJ=cvs ooisaasa 'i/bw i/bw /bai'i 43 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) 602,602,603 602 IK=1 ZE=2.OE-8 GO TO 604 603 IK=2 ZE=(CA*HCO3**2*EXP (_2.341*U/(1.±U))) 604 A=2 .*CA*B 1/B G=2.*SO*B1/B F=2 *j4C*B 1/B H=2 .*CL*B1/B S=2.*SOS*B1/B HCO3=2 . kHCO3*B1/B B=1.E5*2./B ET=E5 CT=C5 SAT=Sk5 XXT=XX5 24 A1=A IF(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.O U=SQRT( 2. 0*(A+F+C)±0 . 5*(S+I-I+HCO3)) BB=A+G EX=(9 .366*U)/(1.0+U) CC=A*G-(2 . 4E5)*EXP R=SQRT(BBBB-4. o*cc) x=(-BB+R)/2 .0 CAS1=4.897E-3-CASO DEL=B*XXT- CAS 1 IF(DEL-X)27, 28,28 27 X=XXT*B XXT=0.O CAS1=O.O (Ex) 1717 x±v=v )1Iös=n z ox(--i-y)o° Fn+s)c ((oDn clxa=vv 6-) 1/n99 ((n+ L (ov+vv-j--i6l7)-=88 l7-V;'.VV=DD OSVD-i16 l79999rzXXXX DDVV;0 9'c'c (xxxx),ai cc oo=ix 9c 0 01 L (vvoz)/((xxxx)aibs-sq-)=ix L IX+OSVD=OsVD 1x-v=v TX-D=O O) 01 1717 91 1I (o) 9'1'I 9 Ti (v) L'1'T L'ill7'ilil I I (osYD) 9Z X+v=v x+o= 1XX=1XX 9/X ISVD+OSVD=OSVD 1XX=LXX SYD 9/1 y=zv ii (s) 08'181'02 191 o8'c1c'o8(J.vs)JI o z=ri 17017 ZO17 oil'oYzot'(L-1vs)aI O1/1VS=Z z z=_[ o o c 01/]2=Z Z=TZ O17 c dX=X ((n-i-oI)/(nP7cz-)) qvci-vaO z+x)-'.-o (svava+1VERO vS+v)XIO 17( vava-'O 17)xivs=aa ivs+vO z+( vciva-O xavLVSLVS= ssva;'-vGl7=3 18 z/zzzzz zz+z=z (ioo-(zzz)sv)aI zI+v=v zIc'olc'olc(v)aI zcc )s z +zvvO)))=zzZ z+z(crnO (au+z(O zzzlzz=zz :s z±ia) z-1VS=1VS r'9'8 s.&s.'vava-(s;&O (s+O 45 551 ET=ET+Z 550 S=S±2.*B*Z 510 A=A-B*Z z=-zl GO TO 81 512 S=S-2.*B*Z IF (5) 550,550,513 513 ET=ET-Z IF (ET)551,551,514 514 SAT=SAT±2 . 0*Z IF (SAT) 552,552,515 515 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*Y F=F-B*Y ET=ET-Y CT=CT+Y A4=A GO TO (600,6o1),IK 601 AA=4,O BB=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=Z 63 ZZ=- ( ( (AA*Z+BB )*Z+CC)*Z+DD) zzz=((3 .O*AA*Z+2.0*BB)*Z+CC) zz=zz/zzz zzz=zz/z z=z+zz IF(ABS(ZZZ)-.001) 64,64,63 64 A=A+Z HCO3=HCO3+2 . IF(HCO3)752, 752, 651 752 HCO3=HCO3-2.Z A=A-Z z=-z1 GO TO 63 651 IF(A) 752,752,753 753 CAL=CAL-Z 600 ZX=(CA*ECO3*2*EXP (-2. 341U/(1 .+ufl) 46 48 49 50 51 52 IF(DEL+1.OE-5)24,48,48 IF(DEL-1.OE-5)49,49,24 DEL=A-A2 IF(DEL+1.OE-5)24, 50,50 IF(DEL-1.OE-5)51,51,24 DEL=A-A3 IF(DEL+1.0E.5)24,52,52 IF(DEL-1.OE-5)8,8,24 8 DELA-A4 IF(DEL+1 .OE-5) 24,66,66 66 IF(DEL-1.OE-5)67,67,24 67 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,ESP 202 FOBMAT(3X56HTHE EXCHANGEABLE SODIUM PERCENTAGE PRESENT IN THE SOIL 1ISF5.1,55H. THE POUNDS OF NACL REQUIRED TO TREAT ONE ACRE OF LAND) PRINT 2O21,TRT,ESPP 2021 FOBNAT(1X2HISF6.1,56H. WITH THIS TREATMENT IT IS ESTIMATED THAT THERE 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/B1 JI=2 GO 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,CAL 1001 FORMAT(1HO2XE1O.3) GO TO 1000 99 STOP END LITERATURE CITED Alexander, A. E., and Johnson, P. 1947. sity Press. Colloid Science, Oxford TJniver- 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 surface conditions 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 1937. matter. Soil Sd. Soc. of Amer. Proc. 2:85-96. 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 (Original Nebr. Agric. Expt. Sta. Bull. No. 112. intake of water. 1939. not seen.) Duely, F. L. Surface factors affecting the rate of intake of water 1939. by soil. Soil Sci. Soc. Amer. Proc. 4:60-64. Chemistry of the Soil. Bear, Firman E. poration, New York. 1965. Reinhold Publishing Cor- 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 sealing and infiltration of exposed soil surface. Agric. Eng. 26:156157, 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 1944. soil samples. Soil Sci. 58:337. 47 48 i.3. Fishman, Marvin J. The Use of Atomic Absorption for Analysis of Natural Water. Atomic Absorption News Letter, Vol. 5, Sept.-Oct, 1966. Harris, J. S. Effect of variation in moisture content on certain properties and on the growth of wheat. Cornell University Agric. Expt. Sta. Bull. No. 352. pp. 801-868. 1914. Harris, J, S., and Evan, A. Effect of replaceable sodium on soil permeability. Soil Sd, 32:445. 1931. Hoon, R, C.,, and Sing, Canga Aluwalia. Physiochemical effect of treating some of bentonite with Na9CO3. J. Indian Chem. Soc., Indust, and News Ed. 5:29-34. 194t. Horton, Robert E. Hydrologic interrelation of water and soils. Soil Sci, Soc. Amer. Proc. 1:401-429. 1936. Huberty, M. R,, and Pillsbury, A. F. Factors influencing infiltration rates into some California soils. Trans. Amer. Geophys. Union 22:686-697. 1941. Izzard, C. F., and Augustine, N. T. Preliminary report on analysis of runoff and paved plot. Trans. Amer. Geophys. Union 11:505509. 1943. Jackson, M. L. Soil Chemical Analysis Advanced Course. Pub, by the author. Dept. of Soils, University of Wisconsin. 1956. Johnson, A. L., and Norton, F. H, Fundamental study of clay. Amer. Ceramic Soc. 24:184-203. 1941. Kelley, W. P. Cation Exchange in Soils, poration, New York. 1948. J. Reinhold Publishing Cor- King, F, N, Principals and conditions of the movement of ground water. U. S. Geol. Survey Ann. Rpt. (Pt. 2) 19:59-294. 1897-98. A procedure for the particle size separation for x-rays diffraction analysis. Soil, Sci. 96: 319-325. 1963. Kittrick, J, A., and I-lope, E. W. Kolodny, 0,, and Joffee, J. S. Soil aggregation and permeability, the relation between moisture content and micro-aggregation on the degree of dispersion in soil. Soil Sci. Soc. Amer. Proc. 4:7-12, 1939. 49 Law, J. Otis. Recent studies in raindrops and erosion. Eng, 21:431-433, 1940, Agric. Lowdermilk, W. C. Influence of forest on runoff, percolation and erosion. Jour. Forestry 28:474-491. Lutz, J. F. properties. The relation of soil erosion to certain inherent soil Soil Sd. 40:439, 1935. Martin, J. P., and Richard, S. J. Influence of exchangeable hydrogen and calcium, sodium, potassium and ammonium at different hydrogen levels on certain physical properties of soils. Soil Sci. Soc. Amer. Proc. 23:235-238, 1959. Mattson, S. The law of soil colloidal behavior, ion adsorption Soil Sci. 31:311-331. 1931. and exchange. McNeal, B. L, Prediction of the effect of mixed solution on soil hydraulic conductivity. Soil Sci. Soc. Amer. Proc. 32:190-193. 1968. McNeal, B. L., and Coleman, N. T, Effect of solution on soil hydraulic conductivity and effect of solution composition on the swelling of extracted soil clays. Soil Sci. Soc. Amer. Proc. 30: 1966. 308-3l2. McNeal, B, L., Norvell, W. A., and Coleman, N. T. Effect of soluSoil tion composition on the swelling of extracted soil clays. Sci. Soc. Amer. Proc. 30:313-317. 1966. McNeal, B. L., Layfield, D. A., Norvell, W. A., and Rhoades, J. D. Factors influencing hydraulic conductivity in the presence of mixed Soil Sci. Soc. Amer. Proc. 32:187-190. 1968. salt solution. Michael, A, S., and Lin, C. S. Effect of counter electroosmosis md. Eng. and sodium ion exchange on peiiueability of kaolinite. 1955. Chem. 47:1249-1253. Munns, E. N., and Lassen, Leon. Controlling water on the land. Soil and Water Conservation No. 1, 5:74. 1950. Nankayana, F. S. Sd. 102:388-393. Deflocculation of soils with sodium salts. J. Soil 1966. Norrish, K., and Quirk, J. P. 1954. Nature 173:255. ite. Manner of swelling of montmorillon- 50 Olphen, H. Van, An Introduction to Clay Colloid Chemistry. Interscience Publishers, New York. (3rd edition) 1966. Quirk, J. P., and Schofield, R. K. The effect of electrolyte concentration on soil permeability. Jour. Soil Sd. 6:163-178. 1955. Rainwater, R. H., and Thatcher, L. L. Methods for Collecting and Analyses of Water Samples. U, S Geol. Survey Water Supply paper no. 1454. 1960. Reeve, R. C. Use of the transmission of water by soil as influmt. Cong. Agric. enced by chemical and physical properties. Eng., Tran, 5th, p. 21-32. 1960. Taylor, Huges S,, and Glasstone, Samuel. A Treatise on Physical 1951. D. Van Nostrand Co., Inc., New York. Chemistry, Vol. 2. Sally, H. L. Lining of Earth Irrigation Channel. House, New York. 1965, Asia Publishing Salter, C. S. A laboratory study of the field percolation rate of U. S. D, A, Tech. Bull. No. 232. 1931, soils. Slichter, Charles S. Theoretical investigation of the motion of ground water. U. S. Geol. Survey Ann. Rpt. (Pt. 2) 19:295-384. 1897-98. U. S. D, A. Methods of characterization and improvement of saline 1954. and alkali soils. Handbook No. 60. Bulk volume and hydraulic Waldron, L. J., and Constantin, G. K. conductivity changes during sodium saturation tests. Soil Sd. Soc. Amer. Proc. 32:175-179. 1968. Sorption of liquids by soil Winterkorn, Hans, and Bayer, L. D. Surface behavior in liquid hydration of clays. colloids 11. 1935. 40:403-319. Soil Sd.
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project