Chapter XIII.. Alkali.

ALKALI.

In the preceding chapters there have been considered the phenomena which obtain under humid conditions. Under exceptional conditions of prolonged drought there occurs an accumulation of soluble mineral substances at or near the surface of the soil. This phenomenon is pronounced in arid and semi-arid regions, and the accumulations of soluble salts occurring in such regions is known in the United States as “alkali,” in India as “reh,” in Africa as “brak,” and in other countries by various local designations. The study of the extreme conditions producing alkali has added materially to the present knowledge of the processes taking place in soil of humid areas. Moreover, alkali-infested areas are themselves becoming of so much importance with the growing needs for further new lands, that it seems wise to give here an outline of the chemical principles involved in their soil solutions.

Alkali is sometimes a single salt, but usually a mixture of some two or more of the chlorides, sulphates, carbonates, bicarbonates, and occasionally the nitrates, phosphates and borates, of sodium, magnesium, potassium, and calcium, and occasionally strontium and lithium. In the United States, when the carbonate of sodium is present to an appreciable extent, the salt mixture is known as black alkali, in contradistinction to white alkali, which latter does not contain sodium carbonate. Generally, but not always, soils containing alkali also contain accumulations of the less soluble salts, calcium carbonate, or calcium sulphate, or a mixture of the two. These substances, sometimes cementing the less soluble mineral components of the soil, sometimes almost pure, are found in layers more or less continuous, and from a fraction of an inch to several feet in thickness, in a position approximately parallel to and at a moderate depth below the surface of the soil. In such cases these layers form a “hard-pan” and frequently the treatment of this type of hard-pan is the most difficult and vexing problem in the management of alkali-bearing soils.

Occasional occurrence of alkali in humid regions, by Frank K. Cameron, Bull. No. =17=, Bureau of Soils, U. S. Dept. Agriculture, 1901, p. 36-38. This phenomenon should not be confused with the surface deposition of various kinds of saline material from springs, which is fairly common in both humid and arid regions, the world over.

Alkali soils of the United States, by Clarence W. Dorsey, Bull. No. =35=, Bureau of Soils, U. S. Dept. Agriculture, 1906.

Black alkali is so called because the caustic solution containing sodium carbonate, in rising to the surface of the soil, dissolves and carries with it organic matter which is subsequently left on the surface in more or less blackish deposits, often ring-like in appearance. It is by no means uncommon, however, to find deposits of “black alkali” which are not black at all, and it is quite common to find “white alkali” so dark in color as to suggest the presence of sodium carbonate, although the latter be absent.

The origin of alkali is often uncertain. In some cases the geological evidences in the area make it certain that the alkali came from the desiccation of former bodies of sea water which had become isolated from the ocean. In other cases the alkali appears to come from the desiccation of lakes which are the depositories of the drainage of a surrounding area, and which have no outlet to the sea. In still other cases it has been supposed that the alkali is derived from wind-borne sea-spray. Various explanations of a more or less special character with regard to particular localities or circumstances are to be found in the literature.

The chemical principles involved in the desiccation of a body of sea water are now pretty well understood, owing mainly to the investigations of van’t Hoff, Meyerhoffer, and their coworkers. The salts in sea water and those constituting “white alkali” are mainly the chlorides and sulphates of sodium, potassium and magnesium. Calcium is also present, appearing in deep deposits as anhydrite, and at the surface as gypsum.

An interesting case is the Billings Area, Montana, where the alkali seems to be derived from the oxidation, solution and subsequent hydrolysis of the pyrites and marcasite of the neighboring Pierre shales. The sulphuric acid thus formed, leaching through shales and sandstones, takes up various bases and the predominating salts in the alkali of this area are the sulphates of sodium and magnesium.

Zur Bildung der ozeanischen Salzablagerungen, von J. H. van’t Hoff, Braunschweig, 1905-09. For a detailed discussion of these results with reference to alkali deposits see: Calcium sulphate in aqueous solutions, by Frank K. Cameron and James M. Bell, Bull. No. =33=, Bureau of Soils, U. S. Dept. Agriculture, 1906.

From the results of this work it is possible to predict the order in which the different salts or minerals will separate from the evaporating solution. At ordinary temperature (25° C) the first salt to be deposited from the dilute solution is gypsum (CaSO₄.2H₂O) followed by halite or sodium chloride (NaCl) in quantity. Sodium chloride continues to separate at all higher concentrations. Next will be deposited kainite (MgSO₄KCl.3H₂O). At the concentration then reached, the stable sulphate of calcium is anhydrite (CaSO₄), which continues to separate from solution as desiccation proceeds. Consequently, if the gypsum previously deposited is yet in contact with the solution, it tends to be transformed to anhydrite and at all higher concentrations the deposition of anhydrite may be expected. As evaporation proceeds a point is reached where kainite and kieserite (MgSO₄.H₂O) separate. Further evaporation brings a concentration at which kieserite and carnallite (MgCl₂.KCl.6H₂O) are precipitated, and as the process proceeds, finally the point is reached where kieserite, carnallite and bischofite (MgCl₂.6H₂O) all three separate with sodium chloride. The final products separating at a higher temperature, 83° C., are the same four solids, sodium chloride, kieserite, carnallite and bischofite. The alternate layers of anhydrite and sodium chloride noticeable in some desiccated sea beds is probably the result of alterations in temperature, anhydrite being less soluble, and sodium chloride somewhat more soluble in hot than in cold water. During warm weather there would be a greater tendency for anhydrite to separate and in colder weather for sodium chloride to be precipitated. Anhydrite at the surface would gradually absorb water vapor from the atmosphere and be transformed to gypsum.

It will be interesting to compare with the above the following brief description of the Stassfurt salt deposits, taken from Ries’s Economic Geology of the United States, (1905), p. 127. “At the bottom is the main bed of rock salt which is broken up into layers 2-5 inches thick by layers of anhydrite. Above this come 200 feet of rock salt, with which are mixed layers of magnesium chloride and polyhalite.... Resting on this is 180 feet of rock salt, with alternating layers of sulphates chiefly kieserite, the sulphate of magnesia. These layers are about 1 foot thick. Lastly, and uppermost, is a 135-foot bed consisting of a series of reddish layers of rock salts of magnesia and potassium, kainite ... kieserite ... carnallite ... tachhydrite ... as well as masses of snow-white boracite.”

As examples, some of the gypsum deposits of Kansas may be cited, according to Haworth, Mineral resources of Kansas, 1897, p. 61, and the classical case at Bex, Switzerland, described by J. G. F. Charpentier, Uber die Salz-Lagerstätte von Bex: Ann. Phys. Chim., =3=, 75-80, (1825), and by G. Bischof, Elements of chemical and physical geology, London, 1854-58, Vol. I, p. 350-1.

Besides the principal salts just described, there may separate at one concentration or another other various double salts including langbeinite (2MgSO₄.K₂SO₄), polyhalite (K₂SO₄.MgSO₄.2CaSO₄.2H₂O), glauberite (CaSO₄.Na₂SO₄), syngenite (CaSO₄.K₂SO₄.H₂O), potassium pentasulphate (K₂SO₄.5CaSO₄.H₂O), krugite (4CaSO₄.K₂SO₄.MgSO₄.2H₂O), and possibly others. These are all stable over very restricted ranges of concentration, however, and if formed, probably seldom persist, but pass over to more stable salts as the desiccation proceeds, and have little more than a passing theoretical interest.

The addition of carbonates to the system introduces some further modifications. In this case lime carbonate is the first salt to be precipitated, followed probably by the same order of deposition as outlined above. As the mother liquor becomes more concentrated, it apparently loses its alkaline character, for the addition of an alcoholic solution of phenolphthalein does not produce the characteristic red color. That the solution does actually contain dissolved carbonates is shown by the appearance of the red color on diluting a portion of the mother liquor with distilled water. An interesting example in nature is furnished by the Great Salt Lake, Utah. A test of the water of this lake in 1899 gave no alkaline reaction with phenolphthalein, but the reaction appeared promptly when distilled water was added, and further examination showed the water to contain about 0.012 per cent. sodium carbonate. Slosson has reported similar cases in Wyoming.

The action of water and aqueous solutions upon soil carbonates, by Frank K. Cameron and James M. Bell, Bull. No. =49=, Bureau of Soils, U. S. Dept. Agriculture, 1907.

Application of the theory of solutions to study of soils, by F. K. Cameron, Report No. =64=, Field Operations of the Bureau of Soils, 1899, p. 149.

Alkali lakes and deposits, by W. C. Knight and E. E. Slosson, Bull. No. =49=, Wyoming Agr. Expt. Station, 1901, p. 108.

One “black alkali” system has been studied with some approach towards completeness. In this case magnesium and potassium salts are not present, the system being composed of water, carbon dioxide, chlorides, sulphates, sodium and calcium salts, with the condition imposed, that the bases are present in amounts more than equivalent to the sulphuric and hydrochloric acids. On desiccation at 25° C calcium carbonate first appears followed by gypsum and then sodium sulphate decahydrate. Next appears a double salt (2CaSO₄.3Na₂SO₄) followed by anhydrous sodium sulphate, the Glauber’s salt which formerly crystallized being no longer stable. Sodium chloride then precipitates and the concentration finally reaches a point where gypsum is no longer stable, and the final group of salts in contact with the evaporating solution under conditions of stable equilibrium consists of calcium carbonate, the double sulphate of soda and lime, anhydrous sodium sulphate and sodium chloride.

The solubility of certain salts present in alkali soils, by Frank K. Cameron, J. M. Bell and W. O. Robinson, Jour. Phys. Chem., =11=, 396-420, (1907).

The desiccation of a lake which serves as the final repository of a regional drainage involves essentially the principles just discussed. The constituents involved are the same. A serious problem involved in the consideration of this source of “alkali” is the high ratio of chlorine to the other constituents, in view of its very low ratio in the rocks from which it comes. The explanation undoubtedly involves the fact that the carbonates and sulphates are constantly being removed as calcium salts from a body of water which is more or less continuously receiving the drainage of any considerable watershed, and is at the same time subject to a relatively high rate of evaporation. The chlorine forming only very soluble salts under such conditions would be segregated and concentrated in the residual mother liquor. Most difficult is it to account for the relatively high ratio of sodium to potassium in alkali from such an origin. Some light is thrown on the subject by the progressive changes in concentration of a lake water which receives a regional drainage under arid conditions. To this end are given the following results of analyses of the waters of Utah Lake, made at different times over an interval of twenty years, and showing that there is a segregation of chlorine and sodium taking place, although in this case the lake has an outlet in the Jordan River.

It has been suggested that the fact that shales or similar geological deposits are frequently to be found near alkali areas, indicates that the shales are the principal sources of the alkali. It is supposed that the constituents of the alkali salts were formed by the action of water on the shale minerals at or about the time the shales were deposited, and carried down with the latter. Subsequently the alkali has been leached out to appear at the surface of soils, generally at a lower level than are the shales.

The water of Utah Lake, by F. K. Cameron: Jour. Am. Chem. Soc., =27=, 113-116, (1905).

ANALYSES OF THE WATER OF UTAH LAKE. RESULTS IN PARTS PER MILLION

=========+========+=========+=======+=========+========= | Clarke | Cameron | Brown | Seidell | Brown | 1883 | 1899 | 1903 | 1904 | 1904 ---------+--------+---------+-------+---------+--------- Ca | 55.8 | 67.6 | 80 | 67.7 | 67 Sr | — | — | — | 1.7 | — Mg | 18.6 | 13.8 | 92 | 73.5 | 86 ---------+--------+---------+-------+---------+--------- Na | 17.7 | 233.7 | 247 | 207.2 | 230 K | ? | ? | 30 | 25.8 | 22 ---------+--------+---------+-------+---------+--------- Li | — | — | — | 0.7 | — SO₄ | 130.6 | 236.7 | 365 | 332.9 | 378 Cl | 12.4 | 316.5 | 336 | 288.5 | 337 HCO₃ | — | — | 266 | 205.5 | 194 CO₃ | 60.9 | 23.7 | — | 24.0 | 11 SiO₂ | 10.0 | — | — | 22.6 | 28 | ————— | ————— | ————— | ————— | ————— Total | 306.0 | 892.0 | 1416 | 1250.1 | 1353 ---------+--------+---------+-------+---------+---------

Sample collected May 18. Lake unusually high.

Sample collected Aug. 31. Lake still high for that season of the year.

The third general origin of alkali supposes that wind-borne sea-spray carries into the air salts which are left in very fine particles on the evaporation of the water, or are deposited on the ordinary atmospheric dust and carried over the land; and that this dust is precipitated here and there as may be determined by the various meteorological conditions which it encounters. All the land surface is supposed to be receiving more or less of it from time to time, but in arid regions the rainfall and drainage is not sufficient to return to the sea as much as is received therefrom.

For a recent interesting and valuable discussion of this subject with reference to a particular area, see: The origin of the salt deposits of Rajputana, by Sir Thomas H. Holland and W. A. K. Christie, Records of the Geological Survey of India, =38=, 154-186, (1909).

It is very probable that wind-borne salts from the sea are being carried over and to some extent being deposited on all the land surfaces of the earth. To what extent this process is taking place, and whether it is sufficient to account for the alkali of any particular region, available data fail to answer satisfactorily. Probably it is always associated with one of the origins of alkali already discussed and is in itself generally of secondary importance.

An argument frequently advanced against the validity of the hypothesis that wind-borne sea-spray is the origin of alkali is that the relative proportions of the several constituents in “alkali” are seldom if ever those obtaining in sea water. This argument does not take into consideration, however, that the several salts in the spray probably separate into crystals of widely different size and specific gravities, and there may well be taking place a selective or sorting action by the wind. More important, undoubtedly, is the selective action taking place in the soil itself; it can only be an accidental coincidence that the constituents of alkali in any particular occurrence should have the same quantitative relations as in the material from which it originated, no matter what may have been the nature of its origin.

In the field, alkali is found in a bewildering array of forms and types. Quite different combinations of constituents may be found in the same field within a few rods or even a few feet, and each case appears to have a distinct origin, to be in fact a law unto itself. Each alkali deposit represents generally the resultant from a mixture of salt which has been dissolved and reprecipitated a number of times, and which while dissolved has been seeping through the soil under gravitational forces, or has been moving through the soil as film water under capillary stresses. In either event the salt mixture has been subject to the power for selective absorption peculiar to the particular soil mass through which it has been moving. Re-solution is seldom an instantaneous process, and different rates of solution necessarily involve some separation of salts. Finally the alkali deposit is usually so mixed with other soil material that there cannot be recognized the characteristic solid phases (such, for instance, as the double sulphates of calcium and another base) which serve as guides in laboratory studies and in certain salt mines. Even if the characteristic salts are deposited in surface soils, it is very doubtful, owing to their hygroscopicity, if any but gypsum, halite and Glauber’s salt can persist for any length of time. The alternations of temperature from night to day characteristic of arid regions, with precipitation of dews, might easily be expected to make noticeable and rapid changes in the characteristics of any given alkali or salt mixture.

It is not surprising, therefore, that attempts to account for the genesis and present appearance of an alkali deposit by comparison with artificial depositions of salt mixtures, as worked out in the laboratory, have generally been disappointing. On the other hand, laboratory studies have been quite fruitful in elucidating the phenomena taking place on the leaching of alkali from a soil, or so-called “alkali reclamation.”

Whatever the origin of the alkali, its segregation at or near the surface of the soil is everywhere much the same; that is, there is a translocation and segregation of soluble salts in the below-surface seepage waters, determined mainly by the topographic features, but partly by the texture and structural properties of the soil and subsoil, with a subsequent rise as capillary water consequent upon evaporation at the surface. Precipitation of the solutes may take place at the surface; more commonly it takes place a few inches below, owing to the fact that under conditions of rapid evaporation, there is ordinarily a discontinuance in the capillary columns or the film water at a point below the surface of the soil, the water diffusing thence into the above-surface atmosphere as the vapor phase.

The composition of alkali is varied. In the vast majority of cases, the world over, the predominating compound is sodium chloride. When calcium carbonate is a conspicuous component of the soil, as a hard-pan or otherwise, sodium carbonate or black alkali is also generally present, or apt to appear when the land is irrigated. When calcium sulphate or gypsum is likewise present, there is less probability of appreciable amounts of black alkali, and where gypsum predominates or the calcium carbonate is present in relatively inappreciable amounts, black alkali is generally absent, and sodium sulphate is an important constituent of the alkali. Relative rates of diffusion, selective absorption, and sometimes other factors are prominent, however, and the character of the alkali in different spots within a few yards of one another may differ greatly. One of the most interesting manifestations of alkali is the occasional occurrence of a predominating amount of calcium chloride which, as a result of its unusually high hygroscopicity, renders the soil damper, and therefore darker in color than the surrounding soil, and frequently causes even experts to suspect the presence of black alkali. Its true nature can, of course, be determined by a simple chemical examination.

The effect of alkali on the physical properties of the soil is often very marked, aside from the cementing action or hard-pan formation by the carbonate or sulphate of lime. Black alkali, by dissolving and segregating the organic matter at the surface, removes from the lower soil layers the “humus” compounds which are of enormous importance to the maintenance of a soil structure favorable to plant growth. Moreover, black alkali is one of the best of deflocculating agents, and consequently soils where it is a noticeable component, frequently puddle with great readiness and are reclaimed with the utmost difficulty. Most of the other constituents of alkali, however, are flocculating or “crumbing” agencies, and if not present in too large amounts tend to increase the readiness with which the soil can be brought into good tilth. In this latter case, by separating in the solid phase, or in forming a viscous soil solution, near the saturation point, they sometimes produce a condition in the soil simulating puddling, and where it occurs below the surface, called an alkali hard-pan.

The management of soils infested with alkali is possible in accordance with a few well established principles. Substantial progress has been made in selecting and breeding plants and strains of plants adapted to such soils. Extreme cases are the use of the so-called Australian salt-bushes as forage crops, and the growing of date-palms which through generations of breeding in the oases of the Sahara can thrive in lands so salty as to destroy most of the halophilous plants. More interesting is the unwitting development of the farmers of Utah of strains of wheat and alfalfa which easily withstand three or four times as high a salt content in the soil as do corresponding crops in other alkali regions, such as New Mexico and Arizona. Black alkali, or one in which sodium carbonate is a prominent constituent, is especially destructive to vegetation, not alone on account of a toxic action on plants, but because in any considerable concentration it has a corrosive action on the plant tissue. Not only on this account but also because of its unfortunate effects on the physical properties of the soil, black alkali has received unusual attention from soil investigators. Hilgard has repeatedly urged the use of gypsum as an “antidote” to black alkali, assuming that under conditions of good drainage and aeration a reaction takes place in accordance with the following equation,

Na₂CO₃ + CaSO₄ = CaCO₃ + Na₂SO₄.

Some mutual relations between alkali soils and vegetation, by Thomas H. Kearney and Frank K. Cameron, Report No. =71=, U. S. Dept. Agriculture, 1902; The date-palm and its utilization in the Southwestern states, by Walter T. Swingle, Bull. =53=, Bureau of Plant Industry, U. S. Dept. Agriculture, 1904; The comparative tolerance of various plants for the salts common in alkali soils, by T. H. Kearney and L. L. Harter, Bull. =113=, Bureau of Plant Industry, U. S. Dept. Agriculture, 1907; Tolerance of alkali by various cultures, by R. H. Loughridge, Bull. =133=, California Agr. Expt. Sta., 1901.

Soils, by E. W. Hilgard. 1906, p. 457-458.

Furthermore, it has been shown that calcium salts and especially calcium sulphate exercise a marked ameliorating effect on the action of other salts upon growing vegetation. On the other hand, the reaction indicated by the equation just given does not run to an end with complete precipitation of the carbonate, and the total amount of alkali is increased in the soil by the addition of the gypsum. Unfortunately, Hilgard’s suggestion has not yet acquired the sanction of satisfactory field demonstration, although it would seem to merit more consideration than has been given it. Inasmuch as lime is generally a prominent constituent of soils containing black alkali, it is possible that the maintenance of good drainage and aeration in the soil is itself the best corrective of black alkali.

With the salts occurring in alkali, it is a generality that the effects produced on higher green plants are relatively less with mixtures than with an equivalent amount of a single salt. It has recently been shown, however, that the contrary is true for at least some kinds of bacterial flora. See, On the lack of antagonism between certain salts, by C. B. Lipman, Bot. Gaz., =49=, 41-50, (1910).

The best use of alkali soils involves irrigation, and it is in the application of irrigation waters that management of alkali soils finds its most highly developed and most important expression. With light sandy soils it has sometimes been found practicable to add sufficient water to carry the alkali down into the soil to such a depth that the crop is well advanced toward maturity before the alkali again rises in sufficient amounts to prove seriously detrimental to the more advanced crops which are generally far more “alkali resistant” than the young seedlings or the germinating seeds. In some cases this procedure can be practiced for a number of years without greatly increasing the seriousness of the alkali conditions, and it may be justified, for a time at least, by economic considerations. Ultimately, however, and more quickly with heavy than with light soils, increasing amounts of alkali must be brought into the surface soil, and this method of irrigating should not be considered as anything more than a temporary expedient. The only procedure which should be seriously considered as a permanent system on an alkali soil, no matter what the texture, is the installation of underground drains, for which purpose, so far, cylindrical tile drains commend themselves as giving the best results. With a well established system of tile drains, the alkali and all excess of soluble salts can be removed from the soil above the drains; and alkali rising from the soil below can, at least very largely, be prevented from rising to the upper soil layers. The reclamation of an alkali tract by underdrainage is not, however, a necessarily quick operation. Generally it must be a matter of several years persistent and careful effort, but once attained should readily be maintained. The reclamation of an alkali tract by flooding and underdrainage involves the reverse process to the crystallization of salt from a brine. If the water in percolating through the soil were long enough in contact with the salts present to become a saturated solution in equilibrium with them, then the composition of the resulting solution or drainage water would depend upon the particular solid phases or salts which are present in the soil, but not on the amounts of these salts; and the relative proportions of the mineral constituents in the drainage water should remain constant until some one of the solid phases in the soil permanently disappears.

In practice, however, the water passes through the soil at different rates from time to time, the flow from the tiles being copious after a flooding but gradually diminishing as time goes on. One or both of two processes can therefore take place. The water may dissolve some of the salts without at any time or place becoming saturated. As the different salts have different rates of solution as well as different absolute solubilities, it would be expected that not only the concentration of the drainage water, but the composition of the dissolved salts would change from time to time. On the other hand, a part of the water may be imagined to percolate slowly through the finer openings, thus forming a saturated solution with respect to the alkali salts which solution, however, will be diluted on entrance to the drains by a part of the water going through the larger soil openings and dissolving but little salt in its passage. In this case, it would be anticipated that the concentration of the drainage water would increase as the amount of flow diminished but the composition of the dissolved salts would remain practically constant until some one or more of the alkali salts was completely removed. There are, unfortunately, but few experimental data by which these can be tested. In the accompanying table are given the results of an investigation on the reclamation of an alkali tract near Salt Lake City, Utah, where observations on the composition of the drainage water were made at frequent intervals for more than three years.

See, Calcium sulphate in aqueous solution, by Frank K. Cameron and James M. Bell, Bull. No. =33=, 1906, p. 10 and 70, and Reclamation of alkali land in Salt Lake Valley, Utah, by Clarence W. Dorsey, Bull. No. =43=, 1907, p. 13, Bureau of Soils, U. S. Dept. Agriculture.

At first sight these results might appear to show that the composition of the salts was remaining reasonably constant. This conclusion must be received with caution, however. Variations do occur in the constituents which are present in smaller amount, but the variations are not systematic and may plausibly be explained by dilution of saturated solution by unsaturated solution on entering the drains. Confining attention therefore to the constituents occurring in larger proportions, namely, sodium chloride, sodium sulphate and sodium bicarbonate (including the normal carbonate) it should be remembered that the percentage of sodium in these three salts does not vary much, and the “constancy” may be more apparent than real. Indeed a close inspection of the results indicates that while the sodium is remaining practically unchanged, there is some decrease in the chlorine and a corresponding increase in the sulph-ion. From this it would follow that the sodium chloride was being washed out of the soil more rapidly, proportionately, than sodium sulphate; and it would also appear that the solution entering the drains was not in final equilibrium with the salts in the soil.

COMPOSITION OF THE SALTS IN THE DRAINAGE WATER FROM THE SWAN TRACT, UTAH

=================+=========+=========+=========+========= Date | Ca | Mg | Na | K |per cent.|per cent.|per cent.|per cent. -----------------+---------+---------+---------+--------- 1902—September | 0.38 | 0.50 | 33.74 | 2.04 October | 0.23 | 0.78 | 34.73 | 1.49 November | 0.19 | 0.74 | 34.42 | 1.40 1903—May | 0.38 | 0.61 | 34.48 | 0.84 June | 0.45 | 0.85 | 34.18 | 1.09 July | 0.50 | 0.80 | 34.06 | 1.25 August | 0.35 | 0.90 | 34.40 | 1.12 September | 0.49 | 0.72 | 34.54 | 1.24 October | 0.47 | 1.02 | 33.43 | 1.52 1904—January | 0.15 | 0.75 | 33.93 | 1.26 February | 0.34 | 0.78 | 34.59 | 0.70 March | 0.29 | 0.77 | 34.57 | 1.28 April | 0.29 | 0.70 | 34.28 | 1.37 May | 0.71 | 0.74 | 26.92 | 4.01 June | 0.37 | 0.70 | 32.60 | 3.55 August | 0.37 | 0.86 | 33.85 | 2.13 September | 0.42 | 0.79 | 34.10 | 1.35 October | 1.04 | 0.60 | 33.01 | 1.86 December | 1.25 | 0.70 | 32.62 | 1.69 1905—February | 0.32 | 0.67 | 33.59 | 0.99 March | 0.31 | 0.66 | 33.46 | 1.30 April | 0.35 | 0.65 | 34.20 | 1.01 May | 0.45 | 0.86 | 33.43 | 1.20 June | 0.40 | 0.94 | 34.05 | 1.32 July | 0.32 | 0.69 | 33.67 | 1.30 August | 0.35 | 1.04 | 33.12 | 1.58 September | 0.42 | 0.82 | 33.39 | 1.26 1906—January | 0.55 | 0.84 | 33.12 | 1.11 =================+=========+=========+=========+========= | SO₄ | Cl | HCO₃ | CO₃ Date |per cent.|per cent.|per cent.|per cent. -----------------+---------+---------+---------+--------- 1902—September | 18.62 | 37.76 | 6.49 | 0.48 October | 19.14 | 39.52 | 5.06 | 0.29 November | 18.61 | 40.46 | 3.95 | 0.23 1903—May | 29.90 | 38.19 | 4.30 | 0.25 June | 17.52 | 41.00 | 4.23 | 0.42 July | 18.24 | 40.24 | 4.67 | 0.30 August | 17.15 | 42.37 | 3.48 | 0.16 September | 17.31 | 42.02 | 3.36 | 0.33 October | 16.08 | 43.28 | 3.33 | 0.30 1904—January | 20.08 | 36.64 | 6.94 | 0.25 February | 18.95 | 40.15 | 4.49 | —— March | 16.31 | 42.28 | 3.81 | 0.19 April | 20.93 | 38.04 | 3.33 | 1.06 May | 21.26 | 40.93 | 4.05 | 1.38 June | 19.94 | 37.42 | 4.05 | 1.37 August | 17.12 | 41.31 | 3.20 | 1.16 September | 19.01 | 39.85 | 4.11 | 0.37 October | 21.42 | 36.63 | 4.68 | 0.76 December | 19.89 | 37.44 | 6.18 | 0.22 1905—February | 22.30 | 33.32 | 8.45 | 0.36 March | 21.60 | 33.86 | 8.46 | 0.35 April | 20.03 | 36.99 | 6.22 | 0.55 May | 20.59 | 36.04 | 6.96 | 0.47 June | 20.89 | 35.85 | 5.71 | 0.84 July | 21.17 | 34.94 | 7.23 | 0.68 August | 21.58 | 35.92 | 5.72 | 0.99 September | 21.18 | 34.85 | 7.41 | 0.67 1906—January | 21.10 | 34.35 | 8.57 | 0.36 -----------------+---------+---------+---------+---------

How long drainage must continue before there is a radical change in the composition of the seepage water cannot be predicted, and unfortunately data regarding this point are not available. It is certain that in time some one or more of the salts in the soil would be removed and the nature of the drainage water would be changed. Alterations in the composition of the drainage water furnish the readiest as well as the best guides as to the changes and the nature of the changes taking place in the soil during the process of reclamation. As a practical matter it should be borne in mind that the persistence of the several salts of the alkali mixture does not mean necessarily that they are evenly distributed in the soil; while yet determining the composition of the water entering the drain, they may have disappeared from the upper soil layers which then may hold a solution of quite different character, suited to the support of crops. In the case just cited the soil contained, before drainage operations were commenced, upwards of 2.7 per cent. of readily soluble salts and would not support any growth other than salt-bushes and similar halophilous plants. Four years later the soil contained less than 0.3 per cent. soluble salts and yielded a very satisfactory crop of alfalfa. In such cases, however, the land cannot be considered as finally reclaimed until a material change in the composition of the drainage water shows that there has been a complete removal of some of the solid salts from that portion of the soil feeding the drains.

The rate at which alkali can be leached from a soil is dependent in a large measure upon the absorptive properties of the soil, and to some extent upon the nature of the salts composing the alkali. The leaching is more rapid from sandy than from clay soils, and white alkali is leached more readily than is black. In general, however, the same laws hold here as in any leaching of a solute from an absorbent, and it has been shown that even in the case of black alkali, the rate of removal under a constant leaching follows the law

dx ————— = K (A - x). dt

The removal of “black alkali” by leaching, by F. K. Cameron and H. E. Patten, Jour. Am. Chem. Soc., =28=, 1639, (1906).

In practice, the water does not percolate through the soil under a constant “head,” but the flow is intermittent, so that the value of the above formula is mainly academic. On the other hand, if the drainage between floodings is thorough, this procedure should be more efficient than any other for causing a rapid removal of the alkali salts, if, as is generally the case, a limited quantity of water is available.

Finally, it remains to be pointed out that the use of excessive amounts of water on alkali tracts is quite as unfortunate in its effects as the use of too little. If water be added to an undrained soil or in excess of the capacity of the drains to remove it, incalculable harm may be done by enormously increasing in the surface soil the amount of salts brought up from the lower layers as the capillary stream rises to the surface in consequence of evaporation there. Should the wetting of the soil proceed so far as to establish good capillary connection with the permanent ground water, the harm may be sufficient to offset in a few weeks or months expensive reclamation efforts of years. The harm to the tract where the water is added may be far less than the harm done to other areas. A large proportion of existing alkali deposits or “spots” results from the evaporation of seepage waters coming sometimes from considerable distances. The over-wetting of a soil means the production of seepage waters which are to appear at the surface somewhere else, generally at a lower level, and frequently means the more or less complete ruin of the soils of the lower level. The experience of India, Africa and our own arid states in the increase of alkali spots following the introduction of irrigation, added to our present theoretical knowledge, should make the planning of an irrigation project without adequate drainage provisions, a stupidity, and its accomplishment a public crime. Quite as important is the development of a public opinion that the individual cultivator who deliberately or carelessly uses excessive amounts of water on his tract is a serious enemy to the body politic, and should be treated as such.

INDEX.

Absorbents, Influence on soil extracts, 38 Absorption by soils, 9, 59, 65 formula, 62 of dyes, 60, 61 rate, 63 selective, 61 Acid digestion of soils, 11, 12 Adsorption, 9, 60 Alkali, 110, 118 Effect on soils, 118 Order of deposition, 112 Reclamation, 117, 121 Source, 111, 117 Antagonism between salts, 120 Apophyllite, Crystallization from water, 35 Apple trees, Effect of grass on, 98 Appleyard, James R. See Walker, James, and Appleyard, James R. Ash analyses, 11, 13 Association of Official Agricultural Chemists’ analyses, quoted, 12 cited, 12 “official method”, 10, 12 “Available” and “non-available” plant-food elements, 8 Averitt, S. D. See Peter, Alfred M., and Averitt, S. D.

Bacteria in soils, 103 Bailey, Liberty H., cited, 5 Balance between supply and removal of mineral plant nutrients, 75 Barium in soils, 107 Bardt, A. See Doroshevskii, A. and Bardt, A. Becquerel, Antoine C., cited, 67 quoted, 68 Bell, James M., and Cameron, Frank K., cited, 28 Bell, James M. See also Cameron, Frank K., and Bell, J. M.; Cameron, Frank K., Bell, J. M., and Robinson, W. O. Benedick, Carl, cited, 55 Birner, H., and Lucanus, B., cited, 70 Bischof, Gustav, cited, 113 Black alkali, 110, 114, 119, 124 Blanck, Edward, cited, 63 Breazeale, James F., acknowledgments, 80 cited, 71 See also Cameron, Frank K., and Breazeale, J. F.; LeClerc, J. A. and Breazeale, J. F. Briggs, Lyman J., cited, 55 and Lapham, Macy H., cited, 41 and McLane, John W., cited, 26 Martin, F. O., and Pearce, J. R., cited, 31 Brooks, William P., cited, 5 Brown, Bailey E., cited, 46 quoted, 46, 115 Bryan, H. See Davis, R. O. E., and Bryan, H. Buckingham, Edgar, cited, 30 Burney, W. B., quoted, 98

Cameron, Frank K., cited, 110, 114, 115 See also Bell, James M., and Cameron, Frank K.; Kearney, Thomas H. and Cameron, Frank K.; Whitney, Milton, and Cameron, Frank K. and Bell, James M., cited, 31, 38, 50, 113, 122 and Breazeale, James F., cited, 62 and Gallagher, Francis E., cited, 24 and Patten, Harrison E., cited, 63, 124 and Robinson, William O., cited, 27, 53 Bell, James M., and Robinson, William O., cited, 114 Calcium nitrate, basic, 108 Carbon dioxide in the soil, 53 Charpentier, Jean G. F., cited, 113 Chemical analysis of soils. See Soil analysis—Chemical. Chesneau, G., cited, 68 Christie, W. A. K. See Holland, Sir Thomas H., and Christie, W. A. K. Clarke, Frank Wigglesworth, cited, 76, 115 Coffey, George N., quoted, 23 Concentration of mineral constituents, 39 Concentration, Plant growth and, 70 Cracking of soil, 22 Creep, 19 Creighton, Henry J. M. See Findlay, Alexander, and Creighton, Henry J. M. Critical moisture content, 24 Crop control methods, 7, 105 plants defined, 1 producing power and aqueous extract, 81 rotation, Natural, 97 Objects of, 4 yields increasing, 16 Crumb structure of soils, 25 Crumbing, 27, 119 Cushman, Allerton S., cited, 36 “Cut-off”, 22, 75 Cyanamid, 108 Czapek, Friedrich, Experiments on root etchings, 9 Criticism of Molisch, 101

Dachnowski, Alfred, cited, 88 Darbishire, Francis V., and Russell, Edward J., cited, 103 Darwin, Horace, cited, 22 Davis, R. O. E., quoted, 63 and Bryan, H., cited, 55 De Candolle, Augustin P., cited, 97 Degradation of rocks, 1 De Roode, Rudolph J. J., quoted, 98 Diaspore, 34 Dittrich, Max., cited, 13 Doroshevskii, A., and Bardt, A., cited, 35 Dorsey, Clarence W., cited, 110, 122 Drainage waters, Composition, 124 Drought limits defined, 29 Dunnington, Francis P., cited, 98 Dust, 20 Dyer, Bernard, cited, 40 method of soil analysis, 10 quoted, 6 Dynamic nature of soil phenomena, 18

Earthworms, 22 European soils, analyses, 16 Erosion, 20 Etchings, Root, 9 Ewart, A. J., cited, 18, 72, 73 Excreta, Toxic, 99, 100, 103

“Factors”, 11 Failyer, George H., cited, 107 See also Schreiner, Oswald, and Failyer, George H. Smith, Joseph G., and Wade, H. R., cited, 32 Fairy rings, 98 Feldspars, 35, 38, 55 Fertilizers, 4, 83, 105 Film water, 24 tenacity, Experiments, 25 Findlay, Alexander, and Creighton, Henry J. M., cited, 53 Fine a soil, to, 4 Fischer, Emil, and Schmidmer, Edward, cited, 61 “Fly-off”, 22, 75 Frear, William, cited, 5 Free, Edward Elway, cited, 20 Friedel, Charles and Sarasin, Edmond, cited, 34

Gallagher, Francis Edward. See Cameron, Frank K. and Gallagher, Francis E. Gannett, Henry, cited, 76 Gaudechon, H. See Muntz, A., and Gaudechon, H. Geikie, Sir Archibald, cited, 75 Gels, 36 Gilbert, Joseph H., cited, 98 Gonnard, F., cited, 35 “Good” and “poor” soils compared, 80 Graham, Thomas, cited, 67 Granulate a soil, to, 4 Grass, Effect on apple trees, 98 Gravitational water, 23 Great Salt Lake, Reaction of water, 113 Green manure, Effect on soil extracts, 87 Gypsum on alkali soils, 119

Hardpan, 111 Harter, Leonard L. See Kearney, Thomas H., and Harter, L. L. Hartwell, Burt L., Wheeler, H. J., and Pember, F. R., cited, 74 Haselhoff, Emil. See König, Joseph, and Haselhoff, E. Haworth, Erasmus, cited, 113 Heileman, William H., quoted, 65 Heterogeneity of soils, 1, 21, 32, 79 Hilgard, Eugene W., cited, 5, 6, 38, 40, 119 Method of soil analysis, 10 Hillebrand, William F., cited, 13 Hills, Joseph L., cited, 5 Holland, Sir Thomas H., and Christie, W. A. K., cited, 116 Hulett, George A., cited, 68 Humic acids, 55 Humus, 61 Hutchinson, Henry B. See Russell, Edward J., and Hutchinson, Henry B. Hydrolysis, 33

Imbibition, 59 Irrigation, 120

Johnson, Samuel W., cited, 40, 77 quoted, 2

Kahlenberg, Louis, and Lincoln, Azariah T., cited, 35 Kaolinite, 34 Kearney, Thomas H., and Cameron, Frank K., cited, 119 and Harter, Leonard L., cited, 119 Kentucky agricultural experiment station, Method of soil analysis, 10 King, Franklin H., cited, 75, 76, 77 quoted, 46, 76 Knight, Wilbur C., and Slosson, Edwin E., cited, 114 König, Joseph, and Haselhoff, E., cited, 8 Kossovich, Petr. S., Experiments on root etchings, 9

Lagergren, Sten, cited, 26 Lake desiccation, 114 Lapham, Macy H. See Briggs, Lyman J., and Lapham, Macy H. Lawes, John B., and Gilbert, Joseph H. See Gilbert, Joseph H. Leather, J. Walter, cited, 23 Le Clerc, J. Arthur, and Breazeale, James F., cited, 14 Lemberg, Johann T., cited, 35 Liebig, Justus, cited, 8, 97 Liebrich, A., cited, 34 Liebreich, quoted, 68 Lieving, quoted, 68 Lincoln, Azariah T. See Kahlenberg, Louis, and Lincoln, Azariah T. Lipman, Jacob G., cited, 72, 103 See also Voorhees, Edward B., and Lipman, Jacob G. Lipman, C. B., cited, 120 Litmus, Absorption of, 66 as indicator, 66 Livingston, Burton E., cited, 85, 88, 97 Loughridge, Robert H., cited, 28, 119 Lucanus, B. See Birner, H., and Lucanus, B.

McGee, W. J., quoted, 22, 76 McLane, John W. See Briggs, Lyman J., and McLane, John W. Manure, Stable, Effect on soil extracts, 84 Martin, F. Oskar. See Briggs, Lyman J., Martin, F. O., and Pearce, J. R. Maxwell, Walter, Method of soil analysis, 10 Mechanical analysis, 31 Merrill, George P., cited, 9 Meyerhoffer, Wilhelm, cited, 111 Meyer, Victor, cited, 67 Minchin, George M., cited, 26 Mineral constituents of soil solution, 31, 37 Mineral plant nutrients, balance between supply and removal, 75 Mississippi River, Soil-carrying power, 21 Mixing of soils, 33 Moisture content, 24 Moisture movement into soil, 28 Molisch, Hans, cited, 101 Mooers, Charles A., cited, 10 Motion in soils, 19 Movement of soils, 20 Muntz, A., and Gaudechon, H., cited, 30 quoted, 24 Murray, Sir John, cited, 75

Newell, Frederick H., cited, 75 Night-soil, 108 Nitrates in agriculture, 108 in soil solution, 103 Nitrogen carriers, 103

“Official method” of soil analysis, 10 Optimum moisture content, 24 Organic compounds, Effect on plants, 82 Organic constituents of soil solution, 54, 79 Orthoclase, Alteration of, 33 Ostwald, Wo., cited, 28 Oxidizing power of roots, 101 Oxygen in the soil, 53 Oxystearic acid, Toxic to plants, 96

Patten, Harrison E., cited, 24, 25, 60 See Cameron, Frank K., and Patten, Harrison E. and Waggaman, William H., cited, 9, 59 and Gallagher, F. E., cited, 59 Pearce, Julia R. See Briggs, Lyman J., Martin, F. O., and Pearce, J. R. Pember, F. R. See Hartwell, Burt L., Wheeler, H. J., and Pember, F. R. Penfield, Samuel L., cited, 13 Percolation experiments, 47 Peter, Alfred, cited, 54 and Averitt, S. D., cited, 10 Pfeffer, Wilhelm F. P., cited, 18, 72, 73, 101 Phlogiston theory, 17 Phosphates, 50 Picoline carboxylic acid, toxic to plants, 96 Plant-food theory, 16 Plant growth and concentration, 70 Plant nutrients, Supply and removal, 75 Plot experiments, 14 “Poor” and “good” soils compared, 80 Pot experiments, 14 Puddling, 25 Pyrogallol, 87 Pyrophyllite, 34

Ragweed, 97, 98 Rainfall, 22, 75 Rajputana, Salt deposits, 116 Rayleigh, Lord, cited, 26 Reed, Howard S. See Schreiner, Oswald, and Reed, Howard S.; Schreiner, Oswald, Reed, Howard S., and Skinner, J. J. Removal of plant nutrients, Supply and, 75 Reversible reactions, 34 Ries, Heinrich, quoted, 112 River waters, Concentration of, 76 Robinson, William O. See Cameron, Frank K., and Robinson, William O.; Cameron, Frank K., Bell, James M., and Robinson, W. O. Rodewald, H., cited, 24 Römer, Hermann. See Wilfarth, Hermann, Römer, Hermann, and Wimmer, G. Root etchings, 9 Root growth mechanism, 19 Roots of growing plants, 18 Rotation of crops, 97 Rothmund, V., cited, 68 “Run-off”, 22, 75 Russell, Edward J., cited, 103 See also Darbishire, Francis V., and Russell, Edward J. and Hutchinson, Henry B, cited, 72

Sachs, Julius, Experiments on root etchings, 9 Salt as fertilizer, Common, 108 Sarasin, Edmond. See Friedel, Charles, and Sarasin, Edmond, 34 Schmidmer, Edward. See, Fischer, Emil, and Schmidmer, Edward. Schreiner, Oswald, quoted, 102 and Failyer, George H., cited, 41, 47 and Reed, Howard S., cited, 100, 101 and Shorey, Edmund C., cited, 95 and Sullivan, M. X., cited, 100 Reed, Howard S., and Skinner. J. J., quoted, 89 Sea water, Desiccation of, 111 Seedlings, Growth of, 74, 80, 82, 84, 86, 88, 100, 102 Seedlings, Toxic action of acids and salts, 62 Seidell, Atherton, quoted, 115 Shaler, Nathaniel S., cited, 20 Shorey, Edmund C., cited, 95 See also Schreiner, Oswald, and Shorey, E. C. Shrinking of soils, 22 Skinner, J. J., quoted, 99, 102 Skinner, J. J. See also Schreiner, Oswald, Reed, Howard S., and Skinner, J. J. Slosson, Edwin E. See Knight, Wilbur C., and Slosson, Edwin E. Smith, Joseph G., quoted, 98 See also Failyer, George H., Smith, Joseph G., and Wade, H. R. Sodium chloride as fertilizer, 108 Soil, the, 1 Soil amendments, 105 analysis, Chemical, 8, 22 Methods, 10 atmosphere, 23 bacteria, 23, 103 control, 4 methods, 4 erosion, 20 fatigue, 100 heaving, 22 individuality, 2 management, 2, 3, 4 minerals, Chief, 32 moisture defined, 1 not a static system, 18 phenomena, Dynamic nature of, 18 shrinking, 22 solution defined, 1 Analyses, 39 Importance of, 2 Organic constituent of, 79 Survey Field Book, cited, 3 translocation by water, 20 wind, 21 Soils, Composition of, 1 Mineral constituents of, 32 Moisture content, 24 Water extracts of, 39 Solid solution defined, 59 Solubility of minerals, 52, 55 Spring, Walthère, cited, 67 Structure, 27 Subsoils, Infertility of, 88 Sullivan, Michael X., cited, 102 quoted, 68 See also Schreiner, Oswald, and Sullivan, M. X. Supply and removal of plant nutrients, 75 Surface effects, 67 Surface tension, 27 Swan tract, Utah, 123 Swingle, Walter T., cited, 119

Taylor, Frederick W., cited, 5 Tennessee agricultural experiment station, Methods of soil analysis, 10 Thorne, Charles E., cited, 5 Tillage methods, 4 Objects of, 4 Tollens, Bernhard C. G., cited, 14 Toxic excreta of roots, 99, 100, 103

Udden, Johan August, quoted, 21 U. S. Dept. of Agriculture, Bureau of Soils. See Soil Survey Field Book. U. S. Geological Survey, cited, 13 Underdrainage, 121 Utah Lake water analyses, 115

Van Hise, Charles R., cited, 35, 36 van’t Hoff, Jakob H., cited, 67, 111 Voorhees, Edward B., and Lipman, Jacob G., cited, 72, 103

Wade, Harold R. See Failyer, George H., Smith, Joseph G., and Wade, H. R. Waggaman, William H. See Patten, Harrison E., and Waggaman, William H. Walker, James, and Appleyard, James R., cited, 60 Washington, Henry S., cited, 13 Water, Movement into soils, 28 vapor, Movement in soils, 29 Way, John T., cited, 9 Weeds, Analyses of, 98 Weinschenk, E., cited, 35 Wheeler, Homer J., cited, 74 Wheeler, Homer J. See also Hartwell, Burt L., Wheeler, H. J., and Pember, F. R. White alkali, 110, 111 Whitney, Milton, cited, 16 and Cameron, Frank K., cited, 26, 42 Wilfarth, Hermann, Römer, Hermann, and Wimmer, G., cited, 14 Willard, Julius T., cited, 5 Wimmer, G. See Wilfarth, Hermann, Römer, Hermann, and Wimmer, G. Wind, 20 Carrying power of, 21 Wind-borne soil material, 21, 33 Wöhler, Friedrich, cited, 35 Wolff, Emil T. von, tables, cited, 77 Woburn, Experiments at, 98

Young, Thomas, cited, 26

Zeolites, 9, 34, 35

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