CHAPTER XXIII.. Utilization and Reclamation of Alkali Lands.

UTILIZATION AND RECLAMATION OF ALKALI LANDS.

Alkali-Resistant Crops.—The most obvious mode of utilizing alkali lands is to occupy them with crops not affected by the noxious salts. Unfortunately but few such crops of general utility have as yet been found for the stronger class of alkali lands. The question is always one of degree, which frequently cannot be decided without an actual determination of the amount and kind of salts to be dealt with, to which the crops can then be adapted in accordance with the greater or less sensitiveness of the several plants, as indicated in the table of tolerances given farther on. But aside from this, there are certain general measures and precautions which in any case will serve to mitigate the effect of the alkali salts. Foremost among these, and applicable everywhere, is the prevention of evaporation to the utmost extent possible.

Counteracting Evaporation.—Since evaporation of the soil-moisture at the surface is what brings the alkali to the level where the main injury to plants occurs, it is obvious that evaporation should be prevented as much as possible. This is the more important, as the saving of soil-moisture, and therefore of irrigation water, is attainable by the same means.

Three methods for this purpose are usually practiced, viz., shading, mulching, and the maintenance of loose tilth in the surface soil to such depth as may be required by the climatic conditions.

As to mulching, it is already well recognized in the alkali regions of California as an effective remedy in light cases. Fruit trees are frequently thus protected, particularly while young, after which their shade alone may (as in the case of low-trained orange trees) suffice to prevent injury. The same often happens in the case of low-trained vines, small-fruit, and vegetables. Sanding of the surface to the depth of several inches was among the first attempts in this direction; but the necessity of cultivation, involving the renewal of the sand each season, renders this a costly method. Straw, leaves, and manure have been more successfully used; but even these, unless employed for the purpose of fertilization, involve more expense and trouble than the simple maintenance of very loose tilth of the surface soil throughout the dry season; a remedy which, of course, is equally applicable to hoed field crops, and is in the case of some of these—e. g., cotton—a necessary condition of cultural success everywhere. The wide prevalence of “light” soils in the arid regions, from causes inherent in the climate itself, renders this condition relatively easy of fulfilment.

Turning-under of Surface Alkali.—Aside, however, from the mere prevention of surface evaporation, another favorable condition is realized by this procedure, namely the commingling of the heavily salt-charged surface-layers with the relatively non-alkaline subsoil. Since in the arid regions the roots of all plants retire farther from the surface because of the deadly drought and heat of summer, it is usually possible to cultivate deeper than could safely be done with growing crops in humid climates. Yet even there, the maxim of “deep preparation and shallow cultivation” is put into practice with advantage, only changing the measurements of depth to correspond with the altered climatic conditions. Thus while in the humid States, three to four inches is the accepted standard of depth for summer cultivation to preserve moisture without injury to the roots, that depth must in the arid region frequently be doubled in order to be effective; and will even then scarcely touch a living root in orchards and vineyards, particularly in unmanured and unirrigated land.

A glance at fig. 63, (chap. 22, p. 431), will show the great advantage of extra-deep preparation in commingling the alkali salts accumulated near the surface with the lower soil-layers, diffusing the salts, say through twelve instead of six inches of soil mass. This will in very many cases suffice to render the growth of ordinary crops possible if, by subsequent frequent and thorough cultivation, surface evaporation, and with it the re-ascent of the salts to the surface, is prevented.

A striking example of the efficiency of this mode of procedure was observed at the Tulare substation, California, where a portion of a very bad alkali spot was trenched to the depth of two feet, throwing the surface soil to the bottom. The spot thus treated produced excellent wheat crops for two years—the time it took the alkali salts to reascend to the surface.

It should therefore be kept in mind that whatever else is done toward reclamation, deep preparation and thorough cultivation must be regarded as prime factors for the maintenance of production on alkali lands.

The Efficacy of Shading, already referred to, is strikingly illustrated in the case of some field crops which, when once established, will thrive on fairly strong alkali soil, provided that a good thick “stand” has once been obtained. This is notably true of the great forage crop of the arid region, alfalfa or lucern. Its seed is extremely sensitive to “black” alkali, and will decay in the ground unless protected against it by the use of gypsum in sowing. But when once a full stand has been obtained, the field may endure for many years without a sign of injury. Here two effects combine, viz., the shading, and the evaporation through the deep roots and abundant foliage, which alone prevents, in a large measure, the ascent of the moisture and salts to the surface. The case is then precisely parallel to that of the natural soil (see p. 432, chapter 22), except that, as irrigation is practiced in order to stimulate production, the sheet of alkali hardpan will be dissolved and its salts spread through the soil more evenly. The result is that so soon as the alfalfa is taken off the ground and the cultivation of other crops is attempted, an altogether unexpectedly large amount of alkali comes to the surface and greatly impedes, if it does not altogether prevent, the immediate planting of other crops. Shallow-rooted annual crops that give but little shade, like the cereals, while measurably impeding the rise of the salts during their growth (see fig. 70, page 452) frequently allow of enough rise after harvest to prevent reseeding the following season.

“Neutralising” Black Alkali.—Since so little carbonate of soda as one-tenth of one per cent may suffice to render some soils uncultivable, it frequently happens that its mere transformation into the sulfate is sufficient to remove all stress from alkali. Gypsum (land plaster) is the cheap and effective agent to bring about this transformation, provided water be also present. The amount required per acre will, of course, vary with the amount of salts in the soil, all the way from a few hundred pounds to several tons in the case of strong alkali spots; but it is not usually necessary to add the entire quantity at once, provided that sufficient be used to neutralize the sodic carbonate near the surface, and enough time be allowed for the action to take place. In very wet soil, and when much gypsum is used, this may occur within a few days; in merely damp soils in the course of months; but usually the effect increases for years, as the salts rise from below.

The effect of gypsum on black-alkali land is often very striking, even to the eye. The blackish puddles and spots disappear, because the gypsum renders the dissolved humus insoluble and thus restores it to the soil. The latter soon loses its hard, puddled condition and crumbles and bulges into a loose mass, into which water now soaks freely, bringing up the previously depressed spots to the general level of the land. On the surface thus changed, seeds now germinate and grow without hindrance; and as the injury from alkali occurs at or near the surface, it is usually best to simply harrow in the plaster, leaving the water to carry it down in solution. Soluble phosphates present are decomposed so as to retain finely divided, but less soluble earth phosphates in the soil.

It must not be forgotten that this beneficial change may go backward if the land thus treated is permitted to be swamped by irrigation water or otherwise. Under the same conditions naturally white alkali may turn black (see above, chapter 22, p. 451). Of course, gypsum is of no benefit whatever on soils containing no “black” alkali, but only (“white”) Glauber’s and common salt.

Removing the Salts from the Soil.—In case the amount of salts in the soil should be so great that even the change worked by gypsum is insufficient to render it available for useful crops, the only remedy left is to remove the salts, partially or wholly, at least from the surface of the land. Three chief methods are available for this purpose. One is to remove the salts, with more or less earth, from the surface at the end of the dry season, either by sweeping or by means of a horse scraper set so as to carry off a certain depth of soil. Thus sometimes in a single season one-third or one-half of the total salts may be got rid of, the loss of a few inches of surface soil being of little moment in the deep soils of the arid region. Another method affording partial relief is to flood the land for a sufficient length of time to carry the alkali three or more feet below the surface, then carefully preventing its re-ascent by suppressing evaporation (see this chapter, p. 455) as much as possible. The best of all, the final and universally efficient remedy, is to leach the alkali salt out of the soil into the country drainage; supplementing by irrigation water what is left undone by the deficient rainfall.

It is not practicable, as many suppose, to wash the salts off the surface by a rush of water, as they instantly soak into the ground at the first touch. Nor is there any certain relief from allowing the water to stand on the land and then drawing it off; in this case also the salts soak down ahead of the water, and the water standing on the surface remains almost unchanged. In very pervious soils and in the case of white alkali, the washing-out can often be accomplished without special provision for underdrainage, by leaving the water on the land sufficiently long. But the laying of regular underdrains greatly accelerates the work, and renders success certain.

Leaching-Down.—In advance of underdrainage, it is quite generally feasible, where the land has been leveled and diked for irrigation by surface flooding, to leach the salts out of the first three or four feet by continued flooding, thus taking them out of reach of the crop roots, or at all events giving the seed an opportunity to escape injury from alkali. This plan is especially effective in the case of alfalfa, the young seedlings of which are very sensitive, while the grown plant is rather resistant. In order to obtain this relief so as to know what is being accomplished, the farmer should ascertain beforehand how fast water will soak down in his ground; for in heavy clay soils, and especially in those containing black alkali, the soakage is sometimes so slow that the upward diffusion of the salts keeps pace with the downward soakage; in which case nothing is accomplished by flooding, and underdrainage is the only remedy. But in most soils of the arid region flooding from three days to a week will remove the alkali beyond reach of the roots of ordinary crops. If subsequently irrigation is done by means of deep furrows, the alkali salts may be either kept at a low level continuously, or if the land be at all pervious, the alkali may ultimately be permanently leached out into the subdrainage by farther flooding. When the alkali has not accumulated near the surface to any great extent, irrigation by deep furrows may, alone, afford all the relief needed.

See p. 242, Chap. 13.

In the case illustrated by figures 71 and 72, irrigation by shallow furrows with water too strongly charged with salts had so far added to the natural alkali-content of the land that the lemon trees were being defoliated. Upon the advice of the California Station the deep-furrow system was adopted, and within two years the results were as shown in figure 72, the salts having been carried down and diluted so as to become harmless.

Underdrainage the Final and Universal Remedy for Alkali.—When we underdrain an alkali soil, we adopt the very means by which the existence of alkali lands in the humid regions is wholly prevented; the leaching-out of the soluble salts formed in soil-weathering as fast as they are formed. The long and abundant experience had with underdrainage in reclaiming saline sea-coast lands, applies directly and cogently to alkali lands. It is the universal remedy for all the evils of alkali, and its only drawback is the first expense, and the necessity for obtaining an outlet for the drain waters, which cannot always be had on the owner’s land. Hence it requires co-operation or legislation to render the great improvement of underdrainage feasible. Such legislation is well established in the old world, and has been enacted in several states even of the humid region. Where irrigation is practiced as a matter of necessity, underdrainage is a correlative necessity, both to avoid the evils of over-irrigation and to relieve the land of noxious alkali salts.

The drainage law now existing in California does not go farther than to authorize the formation of drainage districts, within which the necessary taxes may be levied; and there is some difficulty in securing popular action. But bitter experience will doubtless in time compel unanimity, such as now exists, e. g., in Illinois, where drainage is not nearly so urgently needed as it is in the irrigation states.

Possible Injury to Land by Excessive Leaching.—It should not be forgotten, however, that excessive leaching of underdrained land by flooding is liable to injure the soil in two ways: first, by the removal of valuable soluble plant-food; and further, by rendering the land less retentive of moisture, such retention being favored by the presence of small amounts of alkali salts, not sufficient to injure crops. After the salts have been carried down to a sufficient depth to prevent injury to annual crops, and with proper subsequent attention to the prevention of surface evaporation, the flooding will not need to be repeated for several years. Thus in many soils excellent crops may be grown even in strong alkali land, pending the establishment of permanent drainage systems.

The importance of thoroughly washing the alkali deeply into the soil before the seed is planted, and keeping it there by proper means until the foliage of the plant shades the soil sufficiently to prevent the rise of moisture and alkali, is well illustrated in fields in the region of Bakersfield, Cal., where alfalfa is now growing in soils once heavily charged with alkali. From one of these fields samples of soil were taken where the alkali was supposed to be strongest beneath the alfalfa, and also from an adjoining untreated alkali spot, which was said to represent conditions before alfalfa was planted. The results are given in pounds per acre in four feet depth.

===========================+========+==========+=========+======== |Sulfate.|Carbonate.| Common | Total | | | Salt. | Alkali. ---------------------------+--------+----------+---------+-------- Alkali spot before alfalfa | | | | was planted | 60,120 | 720 | 175,840 | 236,680 | | | | Alfalfa field; alkali | | | | washed down | 14,400 | | 1,040 | 18,640 ---------------------------+--------+----------+---------+--------

Here the surface foot of the natural soil contained nearly 140,000 pounds of common salt, a prohibitory amount. Similar experience has been had near Yuma, Arizona.

Bull. 133, Cal. Expt. Sta., by R. H. Loughridge.

Difficulty in Draining “Black” Alkali Lands.—An important exception to the efficacy of draining, however, occurs in the case of black alkali in most lands. In this case either the impervious hardpan or (in the case of actual alkali spots) the impenetrability of the surface soil itself will render even underdrains ineffective unless the salsoda and its effects on the soil are first destroyed by the use of gypsum, as above detailed. This is not only necessary in order to render drainage and leaching possible, but is also advisable in order to prevent the leaching-out of the valuable humus and soluble phosphates, which are rendered insoluble (but not unavailable to plants) by the action of the gypsum. Wherever black alkali is found in lands not very sandy, the application of gypsum should precede any other efforts toward reclamation. Trees and vines already planted may be temporarily protected from the worst effects of the black alkali by surrounding the trunks with gypsum or with earth abundantly mixed with it. Seeds may be similarly protected in sowing, and young plants in planting.

Swamping of Alkali Lands.—It should, however, be remembered that the swamping of alkali lands, whether of the white or black kind, is fatal not only to their present productiveness, but also, on account of the strong chemical action thus induced, greatly jeopardizes their future usefulness. Many costly investments in orchards and vineyards have thus been rendered unproductive, or have even become a total loss.

Reduction of Alkali by Cropping.—Another method for diminishing the amount of alkali in the soil is the cropping with plants that take up considerable amounts of salts. In taking them into cultivation, it is advisable to remove entirely from the land the salt growth that may naturally cover it, notably the greasewoods (Sarcobatus, Allenrolfea), with their heavy percentage of alkaline ash (12 to 20 per cent). Crop plants adapted to the same object are mentioned farther on. Such crops should also, of course, be wholly removed from the land.

Total Amounts of Salts Compatible with Ordinary Crops; Tolerance of Culture Plants.—Since the amount of alkali that reaches the surface layer is largely dependent upon the varying conditions of rainfall or irrigation, and surface evaporation, it is difficult to foresee to what extent that accumulation may go, unless we know the total amount of salts present that may be called into action. This, as already explained, can ordinarily be ascertained by the examination of one sample representing the average of a soil column of four feet. By calculating the figures so obtained to an acre of ground, we can at least approximate the limits within or beyond which crops will succeed or perish. Applying this procedure to the cases represented in the diagrams (pp. 434, 452, chapter 22) and estimating the weight of the soil per acre-foot at 4,000,000 pounds, we find in the land on which barley refused to grow the figures 32,470 and 43,660 pounds of total salts per acre, respectively corresponding to 0.203 per cent for the first figure (the second, representing only the two surface feet, is not strictly comparable). For the land on which barley gave a full crop, we find for the May sample 25,550 pounds, equivalent to 0.159 per cent for the whole soil column of four feet. It thus appears that for barley the limits of tolerance lie between the above two figures. It should be noted that in this case a full crop of barley was grown even when the alkali consisted of fully one-half of the noxious carbonate of soda; proving that it is not necessary in every case to neutralize the entire amount of that salt by means of gypsum, which in the present case would have required about 9½ tons of gypsum per acre—a prohibitory expenditure.

Relative Injuriousness of the Several Salts.—Of the three sodium salts that usually constitute the bulk of “alkali,” only the carbonate of soda is susceptible of being materially changed by any agent that can practically be applied to land. So far as we know, the salt of sodium least injurious to ordinary vegetation is the sulfate, commonly called Glauber’s salt, which ordinarily forms the chief ingredient of “white” alkali. Thus barley is capable of resisting about five times more of the sulfate than of the carbonate, and quite twice as much as of common salt. Since the maximum percentage that can be resisted by plants varies materially with the kind of soil, it is difficult to give exact figures save with respect to particular cases. For the sandy loam of the Tulare substation, California, for instance, the maximum for cereals may be approximately stated to be one-tenth of 1 per cent for salsoda; a fourth of 1 per cent for common salt; and from forty-five to fifty one-hundredths of one per cent of Glauber’s salt. For clay soils the tolerance is in general markedly less, especially as regards the salsoda; since in their case the injurious effect on the tilling qualities of the soil, already referred to, is superadded to the corrosive action of that salt upon the plant.

Effect of Differences in Composition of Alkali Salts on Beets.—The marked differences which may occur as the result of even slight variations in the proportions of the several salts is well illustrated in the subjoined diagram of observations made by Dr. G. W. Shaw, of the Cal. Expt. station, upon beet fields in the neighborhood of Oxnard, Cal. The lands lie not far from the seashore, and saline water underruns them for considerable distance inland. The soil and subsoil are quite sandy, so that it takes irrigation water only about seven hours to penetrate from the surface to bottom water at seven feet depth. The land on which these observations were made are apparently level to the eye, though probably the alkali belts on which the sugar beets were “poor” are slightly depressed swales.

It will be noted that here the beets were “good” where the sulfate (Glauber’s salt) ranged up to .8%, with .10 to .20 of common salt; but that so soon as the latter rose above .20, the beets were poor despite the low percentage of Glauber’s salt; then became “good” again so soon as the common salt fell below .20%, although the Glauber’s salt increased.

TOLERANCE OF VARIOUS CROP PLANTS.

The following table, compiled by Dr. R. H. Loughridge mainly from his own observations, gives the details of the tolerance for various culture plants as ascertained at the several experiment substations in California, as well as at other points in that State and in Arizona where critical cases could be found. It is thought preferable to investigate analytically such cases in the field, rather than to attempt to obtain results from small-scale experiments artificially arranged, in which sources of error arising from evaporation and other causes are most difficult to avoid.

Bulletins Nos. 128, 133 and 140, Calif. Expt. Station.

The table is so arranged as to show the maximum tolerance thus far observed for each of the three single ingredients, as well as the maximum of total salts found compatible with good growth. In view of the extremely variable proportions between the three chief ingredients found in nature, this seems to be the only manner in which the observations made can be intelligibly presented, until perhaps a great number of such data shall enable us to evolve mathematical formulæ expressing the tolerance for the possible mixtures for each plant. For it is certain that the tolerance-figures will be quite different in presence of other salts, from those that would be obtained for each salt separately; or for the calculated mean of such separate determinations, proportionally pro-rated. It must also be remembered that in all alkali soils, lime carbonate is abundantly present, as is, nearly always, a greater or less amount of the sulfate (gypsum). As already stated, according to the investigations of Cameron not only these compounds, but also calcium chlorid, exert a protective influence against the injury to plant growth from compounds of sodium and potassium. The figures here given can therefore be regarded only as approximations, subject to correction by farther observation. They are arranged from the highest tolerances downward, for each of the three ingredients, as well as for the totals. The latter are not, of course, the sums of the figures given in the preceding columns, but independent data.

HIGHEST AMOUNT OF ALKALI IN WHICH FRUIT TREES WERE FOUND UNAFFECTED.

Arranged from highest to lowest. Pounds per acre in four feet depth.

=================+===============+================+================= Sulfates | Carbonate | Chlorid | Total Alkali. (Glauber’s Salt).| (Salsoda). | (Common Salt).| -----------------+---------------+----------------+----------------- Grapes 40,800| Grapes 7,550| Grapes 9,640| Grapes 45,700 Olives 30,640| Oranges 3,840| Olives 6,640| Olives 40,160 Figs 24,480| Olives 2,880| Oranges 3,360| Almonds 25,560 Almonds 22,720| Pears 1,760| Almonds 2,400| Figs 26,400 Oranges 18,600| Almonds 1,440| Mulberry 2,240| Oranges 21,840 Pears 17,800| Prunes 1,360| Pears 1,360| Pears 20,920 Apples 14,240| Figs 1,120| Apples 1,240| Apples 16,120 Peaches 9,600| Peaches 680| Prunes 1,200| Prunes 11,800 Prunes 9,240| Apples 640| Peaches 1,000| Peaches 11,280 Apricots 8,640| Apricots 480| Apricots 960| Apricots 10,080 Lemons 4,480| Lemons 480| Lemons 800| Lemons 5,760 Mulberry 3,360| Mulberry 160| Figs 800| Mulberry 5,760 -----------------+---------------+----------------+-----------------

The several columns of figures are independent of each other; the “total” alkali is not the summation for the three salts in the same line.

OTHER TREES. ---------------------+-------------------+-------------------- Kölreuteria 51,040| Kölreuteria 9,920| Or. Sycamore 20,320 Eucal. am. 34,720| Or. Sycamore 3,200| Kölreuteria 12,640 Or. Sycamore 19,240| Date Palm. 2,800| Eucal. am. 2,960 Wash. Palm 13,040| Eucal. am. 2,720| Camph. Tree 1,420 Date Palm 5,500| Wash. Palm 1,200| Wash. Palm 1,040 Camph. Tree 5,280| Camph. Tree 320| ---------------------+-------------------+-------------------- Kölreuteria 73,600 Or. Sycamore. 42,760 Eucal. am. 40,400 Wash. Palm 15,200 Date Palm 8,328 Camph. Tree 7,020 ---------------------

SMALL CULTURES. ---------------------+-------------------+--------------------- Saltbush 125,640| Saltbush 18,560| Modiola 40,860 Alfalfa, old 102,480| Barley 12,170| Saltbush 12,520 Alfalfa, young 11,120| Bur Clover 11,300| Sorghum 9,680 Hairy Vetch 63,720| Sorghum 9,840| Celery 9,600 Sorghum 61,840| Radish 8,720| Onions 5,810 Sugar Beet 52,640| Modiola 4,760| Potatoes 5,810 Sunflower 52,640| Sugar Beet 4,000| Sunflower 5,440 Radish 51,880| Gluten Wheat 3,000| Sugar Beet 10,240 Artichoke 38,720| Artichoke 2,760| Barley 5,100 Carrot 24,880| Lupin 2,720| Hairy Vetch 3,160 Gluten Wheat 20,960| Hairy Vetch 2,480| Lupin 3,040 Wheat 15,120| Alfalfa 2,360| Carrot 2,360 Barley 12,020| Grasses 2,300| Radish 2,240 Goat’s Rue 10,880| Kaffir Corn 1,800| Rye 1,720 Rye 9,800| Sweet Corn 1,800| Artichoke 1,480 Cañaigre 9,160| Sunflower 1,760| Gluten Wheat 1,480 Ray Grass 6,920| Wheat 1,480| Wheat 1,160 Modiola 6,800| Carrot 1,240| Grasses 1,000 Bur Clover 5,700| Rye 960| White Melilot 440 Lupin 5,440| Goat’s Rue 760| Goat’s Rue 160 White Melilot 4,920| White Melilot 480| Cañaigre 80 Celery 4,080| Cañaigre 120| Saltgrass 44,000| Saltgrass 136,270| Saltgrass 70,360 ----------------------+-------------------+--------------------- Saltbush 156,720 Alfalfa, old 110,320 Alfalfa, young 13,120 Sorghum 81,360 Hairy Vetch 69,360 Radish 62,840 Sunflower 59,840 Sugar Beet 59,840 Modiola 52,420 Artichoke 42,960 Carrot 28,480 Barley 25,520 Gluten Wheat 24,320 Wheat 17,280 Bur Clover 17,000 Celery 13,680 Rye 12,480 Goat’s Rue 11,800 Lupin 11,200 Cañaigre 9,360 Onions 38,480 Potatoes 38,480 Saltgrass 381,110 ----------------------

Figures taken from Bulletin 169, Calif. Expt. Station, June, 1905.

Comments on the Above Table.—Considering in this table, first, the plants suitable for the stronger class of alkali lands, it may be said generally that the search for widely acceptable kinds has not been very successful. It is true that cattle will nibble green salt grass (Distichlis spicata), but will soon leave it for any dry feed that may be within reach. The enormous amount of salts which it will tolerate in the soil on which it grows, and the doubtless correspondingly large amount of those salts which it will absorb, judging from its taste, sufficiently explain the reluctance of cattle to feed on it to any considerable extent.

The same is true of all the fleshy plants that grow on the stronger alkali lands, and are known under the general designation of “alkali weeds.” When stock unaccustomed to it are forced by hunger to feed on such vegetation to any considerable extent, disordered digestion is apt to result; which in such ranges, however, is often counteracted by feeding on aromatic or astringent antidotes, such as the gray sagebrush and the more or less resinous herbage of plants of the sunflower family.

In the Great Basin region, lying between the Sierra Nevada and the front range of the Rocky Mountains, there are, aside from the grasses, numerous herbaceous and shrubby plants that afford valuable pasturage for stock, and some of these grow on moderately strong alkali land; the same is true in California. It is quite possible that some of these will be found to lend themselves to ready propagation for culture purposes as well as they do for restocking the ranges. But thus far none have found wider acceptance, probably because their stiff branches and upright habit render them inconvenient to handle. It will require more extended experience and experiment before any of these will be definitely adopted for propagation by farmers and stockmen.

See Bulletin No. 16 of the Wyoming Experiment Station; also Bulletin Nos, 2 and 12 of the Division of Agrostology, and Farmers’ Bulletin No. 108, U. S. Department of Agriculture.

Saltbushes, and Herbaceous Crops.

Australian Saltbushes.—Experience in California indicates that in the more southerly portion of the arid region, unpalatable native plants may be largely replaced, even on the ranges, by one or more species of the Australian saltbushes (Atriplex spp.), long ago recommended by Baron von Mueller of Melbourne; of which one (A. semibaccata) has proved eminently adapted to the climate and soil of California and is readily eaten by all kinds of stock. The facility with which it is propagated, its quick development, the large amount of feed yielded on a given area, even on the strongest alkali land ordinarily found, and its thin, flexible stems, permitting it to be handled very much like alfalfa, seem to commend it especially to the farmers’ consideration wherever better forage plants cannot be grown and the climate will permit of its use. It does not, however, resist the severe cold of the interior plateau country, and is wholly out of place in the Pacific Coast region where summer fogs prevail. Most of the other Australian species have an upright, shrubby habit, which adapts them better to browsing than to pasture proper. The same is true of the Argentine species (A. Cachiyuyum), which in its native pampas is highly esteemed for that purpose, and succeeds well in California. Of other Australian saltbushes, A. halimoides, vesicaria and leptocarpa are the most promising; the latter is somewhat similar in habit to the semibaccata, but is not as vigorous a grower. Since some of the saltbushes take up nearly one fifth of their dry weight of ash ingredients, largely common salt, the complete removal from the land of a five-ton crop of saltbush hay will take away nearly a ton of the alkali salts per acre. This will in the course of some years be quite sufficient to reduce materially the saline contents of the land, and will frequently render possible the culture of ordinary crops.

Analyses made at the California station show 19.37 percent of ash in the air-dry matter of Australian saltbush. (See California Station Bulletin No. 105; E. S. R., vol. 6, p. 718). Analyses of Russian thistle have been reported showing over 20 per cent of ash in dry matter. (See Minnesota Sta. Bulletin No. 34; Iowa Sta. Bull. No. 26; E. S. R., vol. 6, pp. 552-553).

Modiola.—Alongside of the saltbushes, the Chilean plant Modiola procumbens, now generally known as modiola simply, deserves attention, as it makes acceptable pasture where alfalfa fails to make a stand on account of alkali. It is a trailing plant with medium-sized, roundish foliage, and roots freely at the joints where they touch the ground. Unlike the saltbushes it is therefore a formidable weed where it is not wanted; but as according to California experience it resists as much as 52,000 pounds of salts per acre, even when 41,000 of these is common salt, it is likely to be useful in many cases, particularly as an admixture to a saltbush diet for stock, as it does not absorb as much salt as the latter. It seems best adapted to pasturage.

As the table shows that, once grown to the age of a few years, alfalfa will resist a percentage of alkali next to the saltbush, it will generally be worth while, in lands otherwise adapted to alfalfa, to prepare the land by leaching-down (see above) so as to secure a stand of the more valuable crop.

Native Grasses.—Of all known plants that stock will eat somewhat freely, the tussock grass (Sporobolus airoides, of which a figure is given farther on), a native of the southern arid region, endures the largest amounts of alkali; having been found growing well on land containing the enormous amount of nearly half a million pounds of salts per acre, although it will thrive with only 49,000 pounds in the soil. What it will do under cultivation has never been fairly tested; but its bare tussocks, killed by the excessive browsing of stock, testify to its acceptableness as forage. It does not seem to absorb excessive amounts of salts.

It should be understood that the plants so referred to are exclusively the true grasses, recognized as such by every child, and not forage plants generally; which are sometimes so designated; not only by farmers, but by some authors who fail to appreciate the practical importance of the distinction, which makes it necessary that farmers should be taught to understand it.

Aside from the alkali grass proper (Distichlis), mentioned above, the so-called rye grass of the Northwest (Elymus condensatus) is probably, next to the tussock grass, the most resistant species among the wild grasses. Its southern form, with several others not positively identified, occupies largely the milder alkali lands of southern California. This grass, though rather coarse, is regularly cut for hay in the low grounds of Oregon and Washington.

Doubtless some of the indigenous grasses of the interior plateau region and of the great plains east of the Rocky Mountains, such as the buffalo and grama grasses, as well as several of the wheat grasses (Agropyron) and bunch grasses (Festuca, Poa, Stipa, etc.) will prove resistant to larger proportions of alkali than the meadow and pasture grasses of the regions of summer rains.

Cultivated Grasses.—The superficial rooting and fine fibrous roots of the true annual grasses render them, as a whole, rather sensitive to alkali; yet the cereals—barley, wheat, rye and oats—resist, as the table shows, the average alkali salts to the extent of from 17,000 total salts, with not exceeding 1500 pounds of carbonate, in the case of the more delicate varieties of wheat, to over 25,000 pounds per acre in the case of barley, which with the gluten wheats and rye seems to have the highest tolerance-figure. The special adaptation of gluten wheats to arid conditions is thus emphasized. The roots of these cereals are comparatively stout, with thick epidermis.

Among the cultivated forage grasses proper, the Australian variety of the English ray (generally miscalled rye) grass seems most resistant. The eastern fescues, Kentucky blue grass, and others at home in the humid region are easily injured, as those who try to maintain lawns on alkali-tainted lands, or by irrigation with alkali waters, know to their sorrow. To these grasses common salt and bittern (magnesium chlorid) seem to be particularly injurious, and they tolerate but little “black alkali.”

On the rather close-textured soil at Chino, California, the loliums, including the darnel (“California cheat”), and the Australian and Italian ray (“rye”) grasses, succeed fairly on land containing as much as 6,000 pounds of (white) salts. Most other cultivated grasses failed conspicuously alongside of these. It must be remembered that in more loose-textured, sandy lands than those in which these tests were made, the above figures for tolerance would probably be increased by 30 percent or more.

Maize is rather sensitive to alkali, and suffers even on slightly alkaline land, owing doubtless to the large development of fine white rootlets near the surface, so familiar to corn-growers. The Sorghums, and especially Egyptian corn (durra) are much less sensitive, as the table shows, and are among the first crops to be tried on alkali lands. The related millets share this resistance more or less, and we often see on cultivated lands in the alkali region fine stands of barnyard grass (Panicum crusgalli) of which the variety (?) P. muticum is said by observers of the U. S. Dept. of Agriculture to be specially resistant, and acceptable to stock. One of the most successful grasses on the light alkali lands near Chino, where most of the commonly cultivated grasses fail, was a near relative of the barnyard grass, the Eleusine coracana, which produces heavy crops of a millet-like grain much relished by poultry, and also by stock. This grass, largely grown in Egypt, has succeeded well all over the ground whose alkali content ranges up to 12,000 pounds per acre, but failed where the salts reached 38,840 pounds in the surface foot. Next to this, in point of success, were the pearl millet (Pennisetum typhoideum) and teosinte, Hungarian brome grass, and Japanese millet, on land containing about 9,000 pounds of (chiefly “white”) salts per acre.

Other Herbaceous Crops. Legumes.—Both the natural growth of alkali lands and experimental tests seem to show that this entire family (peas, beans, clovers, etc.) are among the more sensitive and least available wherever black alkali exists; while fairly tolerant of the white (neutral) salts. Apparently a very little salsoda suffices to destroy the tubercle-forming organisms that are so important a medium of nitrogen-nutrition in these plants. Excepting the melilots, alfalfa with its hard, stout and long taproot, seems to resist best of all these plants.

As a general thing, taprooted plants, when once established, resist best, for the obvious reason that the main mass of their feeding roots reaches below the danger level. Another favoring condition, already alluded to, is heavy foliage and consequent shading of the ground; alfalfa happens to combine both of these advantages. There has been some difficulty in obtaining a full stand of alfalfa in the portion of the Chino substation tract containing from 4000 to 6000 pounds of (largely black) alkali salts per acre; but once obtained, it has done very well.

The only other plant of this family that succeeds well on this land, and even (at Tulare) on soil considerably stronger (probably between 20,000 and 30,000 pounds) are the two melilots, M. indica, and alba; the latter (the Bokhara clover) is a forage plant of no mean value in moist climates, but somewhat restricted in its use in the arid region because of the very high aroma it develops, especially in alkali lands; so that stock will eat only limited amounts, best when intermixed with other forage, such as the saltbushes. The yellow melilot is highly recommended by the Arizona Experiment Station as a green-manure plant for winter growth; but farther north it is a summer-growing plant only, and is refused by stock. As already stated, very few plants belonging to this family are naturally found on alkali lands, and attempts to grow them, even where only Glauber’s salt is present, have been but very moderately successful.

For most of the legumes the limit of full success seems to lie between 3000 and 4000 pounds to the acre. A marked exception, however, occurs in the case of the hairy vetch, as shown in the table, where it is credited, on the basis of repeated experiments, with a tolerance of nearly 70,000 pounds. This amount was attained, however, in rather sandy soils. Probably some of the Algerian vetches will likewise prove more resistant than those which are natives of humid climates.

Mustard Family.—As in the case of the legumes, wild plants of the mustard family are rare on alkali lands; and correspondingly, the cultivated mustard, kale, rape, etc., fail even on land quite weak in alkali. Their limit of tolerance seems to lie near 4,000 to 5,000 pounds per acre even of white salts. Hence turnips and radishes do not flourish on alkali lands.

Sunflower Family.—Several of the hardiest of the native “alkali weeds” belong to the sunflower family, and the common wild sunflowers (Helianthus californicus and H. annuus) are common on lands pretty strongly alkaline. The cultivated Russian sunflower, as the table shows, resists the effects of nearly 60,000 pounds of total alkali, of which 52,640 pounds was sulfate (Glauber’s salt), and 5440 common salt. This, it will be seen, is a very high tolerance, so that this sunflower, yielding such excellent poultry feed, is very widely available. Correspondingly, the “Jerusalem artichoke,” itself a sunflower, is among the available crops on moderately strong alkali soils; and so, doubtless, are other members of the same relationship not yet tested, such as the true artichoke, salsify, etc. Chicory, belonging to the same family, yielded roots at the rate of twelve tons per acre, on land of the Chino tract containing about 8,000 pounds of salts per acre.

Root Crops.—It seems to be generally true that root crops suffer in quality, however satisfactory may be the quantity, harvested on lands rich in salts, and especially in chlorids (common salt). It was noted at the Tulare substation (California) that the tubers of the artichoke were inclined to be “squashy” in the stronger alkali land, and failed to keep well; the same was true of potatoes, which were very watery; and also of turnips and carrots. It is a fact well known in Europe, that potatoes manured with kainit (chlorids of potassium and sodium) are unfit for the manufacture of starch, and are generally of inferior quality. But this is found not to be the case when, instead of the chlorids, the sulfate is used; hence the advice, often repeated by the California station, that farmers desiring to use potash fertilizers should call for the “high-grade sulfate” instead of the cheaper kainit, which adds to the injurious salts already so commonly present in lowland soils of the arid region. Such root crops are, however, available for stock feed.

The common beet (including the mangel-wurzel) is known to succeed well on saline seashore lands, and it maintains its reputation on alkali lands also. Being especially tolerant of common salt, it may be grown where other crops fail on this account; but the roots so grown are strongly charged with common salt, and have, as is well known, been used for the purpose of removing excess of the same from sea-coast-marsh lands. Such roots are wholly unfit for sugar-making.

It is quite otherwise with Glauber’s salt (sodium sulfate); and as this is very commonly predominant in alkali lands, either before or after the gypsum treatment, this fact is of great importance, for it frequently permits of the successful growing of the sugar beet; as has been abundantly proved at the Chino ranch, where land containing as much as 60,000 pounds of salts, mostly this compound, has yielded roots of very high grade, both as to sugar percentage and purity. But the analyses of the Oxnard soil show that more than 10,000 pounds of common salt will be required to render sugar beets unsatisfactory for sugar-making.

Passing to stem crops, we find that asparagus, originally itself a denizen of the sea-board, resists considerable amounts (not yet exactly determined) of common salt as well as of Glauber’s salt. It is even claimed that when grown with a dressing of common salt the asparagus is more tender and savory. But it is quite sensitive to “black alkali,” which must be neutralized with gypsum to render it harmless.

Celery did well with 13,640 pounds, of which nearly 10,000 was common salt. But with 30,000 pounds the plants were killed.

Rhubarb was a conspicuous failure, even in the weak and mostly “white” alkali lands of the Chino station tract.

Textile Plants.—Japanese hemp, while young, seemed to have a hard struggle with the alkali, but at the end of the season stood eight feet high. The ramie plant, also, will bear moderately strong alkali, apparently somewhat over 12,000 pounds per acre. Flax has not been tested in cultivation; but the wide distribution of wild flax all over the arid portions of the States of Oregon and Washington, would seem to indicate that it is not very sensitive. Another textile plant, the Indian mallow (Abutilon avicennae), was found to fail on the Chino alkali soil. But its close relative, cotton, does not seem to be specially sensitive, according to the experience had with it in the Merced river bottom in California; and its culture is extensive in Egypt, where no particular care seems to be exercised in selecting the land for the crop. It is just possible that the saline content of the soil has in California, as well as in the Atlantic sea-islands, contributed to the superior length of the fiber shown in the measurements made during the Census work of 1880.

Report on Cotton Culture; 10th Census of the United States, vol. 5, pp. 23 to 34.

Tolerance of Shrubs and Trees.

Grapevines.—The European grape, Vitis vinifera, is quite tolerant of white or neutral alkali salts, and will resist even a moderate amount of the black so long as no hardpan is allowed to form. At the Tulare substation it was found that grapevines did well in sandy land containing 35,230 pounds of alkali salts, of which one half was Glauber’s salt, 9,640 pounds carbonate of soda, 7,550 pounds of common salt, and 750 pounds nitrate of soda. They were badly distressed where, of a total of 37,020 pounds of alkali salts, 25,620 pounds was carbonate of soda; while where the vines had died out, there was found a total of 73,930 pounds, with 37,280 pounds of carbonate. The European vine, then, is considerably more resistant of alkali even in its worst (black) form, than barley and rye, at least on sandy land; and it seems likely that the native grapevines of the Pacific coast, californica, and arizonica, would resist even better; a point still under experiment.

Experience, however, has shown that vines rapidly succumb when by excessive irrigation the bottom water is allowed to rise, increasing the amount of alkali salts near the surface, and shallowing the soil at their disposal. Such over-irrigation has been a fruitful cause of injury to vineyards in the Fresno region, and would doubtless if practiced kill most of the vines at the Tulare substation, which are now flourishing. In such cases, sometimes the formation of hardpan is followed by that of a concentrated alkaline solution above it, strong enough to corrode the roots themselves, and not only killing the vines, but rendering the land unfit for any agricultural use whatsoever. The swamping of alkali lands, whether of the white or black kind, is not only fatal to their present productiveness, but, on account of the strong chemical action thus induced, greatly jeopardizes their future usefulness. Many costly investments in orchards and vineyards have thus been rendered unproductive, or have even become a total loss.

It should be remembered in this connection that as the roots of vines will, when unobstructed, go to depths of fifteen and even twenty feet, a subsequent rise of the bottom water from leaky irrigation ditches will drown out the ends of the deep roots and thus cause the whole root system to become diseased, inevitably resulting in unproductiveness, if not death, of the vine.

Citrus Trees.—Although the high figure of nearly 27,000 pounds for the tolerance of citrus trees, as given in the table, seems to place them rather high on the list, such high tolerance actually occurs only in very sandy soils, and when common salt is in small proportion. Generally speaking, the citrus tribe are rather sensitive to alkali salts, and more especially to common salt. In fact, as to the high tolerance-figure given in the table, observed in sandy land, the alkali there contained only a trace of common salt. Young seedling trees are particularly sensitive; so that it is often difficult to obtain a stand even when, later on, the feeding roots descend beyond the reach of injury. In the close-textured lands of Chino, young trees hardly maintained life with more than 5,000 pounds of total salts. Near Riverside, full-grown trees perished under the influence of bottom water containing 0.25%, or 146 grains of salt per gallon, which impregnated the ground; corresponding to about 9,000 pounds per acre in four feet.

In the sandy loam lands near Corona, trees eight years old suffered severely when by irrigation with alkali-water the alkali-content of the land reached 11,000 pounds per acre; as illustrated in Figs. Nos. 44, and 45. At another point in the same region, two representative trees were selected for comparison, five rows apart on land absolutely identical; one of these retained its leaves, though suffering, the other was completely leafless. The leaching of the alkali to the depth of four feet gave the following results, calculated to pounds per acre:

Sulfates. Carbonates. Chlorids. Total.

Poor tree 4,720 1,680 2,520 8,920 Better tree 4,120 2,360 720 7,200

Here it is apparently the excess of common salt to which the difference is due, and this despite the higher content of carbonate of soda in the soil bearing the better tree.

On the other hand, at the Tulare substation orange trees (sour stock) maintain vigorous growth and good bearing in a very sandy tract which to the depth of seven feet showed an aggregate content of 26,840 pounds of salts (or 22,780 to four feet depth); but which is never irrigated. (See diagram No. 66). The salts in this case consists wholly of sulfate and carbonate of soda in the ratio of fifty-four to forty-two, implying the presence of nearly 12,000 pounds of salsoda within reach of the tree roots; yet in the absence of common salt, no perceptible injury or even stress upon the trees has been noted.

According to observations made in San Diego county, Calif., lemon trees are even more sensitive to common salt than oranges, since a total content of 8,000 pounds per acre, about one-third of which was common salt, seemed to render the trees wholly unprofitable.

In view of these facts, showing that common salt is the portion of alkali by far most injurious to citrus trees, great care should be taken in the use of irrigation waters to exclude those charged with that compound; and also to avoid locating citrus orchards on land already impregnated with common salt.

The olive tree, as the table shows, is among the most resistant to alkali salts, approaching the grape in this respect. This might have been anticipated from its extended culture in the arid regions of the old world, including Palestine and northern Africa, where alkali lands abound. It is probable that the figure given in the table does not yet show the extreme limit of its endurance.

California experience with the date palm, as the table shows, credits it with an endurance not exceeding 8320 pounds of total salts. This is doubtless an underestimate, for in the Sahara desert and Egypt it is credited with being the culture which will succeed in stronger alkali than any other cultural plant; and, according to Mr. Means of the United States Department of Agriculture, it is sometimes irrigated with water containing as much as 200 grains of salts per gallon. It should be remembered, however, that these trees always grow in very sandy lands; and in the desert regions it is often grown below the surface of the ground, so as to render it wholly independent of the alkali accumulations on the surface. The extreme limit of its endurance must therefore remain in doubt until more extended experiments have made more definite data available.

Deciduous Orchard Trees.

Among deciduous orchard trees, strangely enough, the almond stands alongside of the fig in alkali-resistance, as indicated in the table. The peach seems to be much more sensitive, ranking near the apricot and prune, whose tolerance is less than half as high. That the pear and apple, generally counted among the more northern fruits in the humid region, should excel these stone fruits in endurance of alkali, is rather unexpected; and the figures concerning the whole group of these rosaceous fruits admonish us that it is unsafe to predict, without trial, what may be the outcome of culture tests. Thus plum trees, apparently in good condition, sometimes suddenly begin to fail when starting to bear; the fruit appears normal on the outside for a time, but the pit fails to form, being at times flattened out like a piece of pasteboard; and the fruit does not mature. Yet there is no observable injury to the base of the trunk, or to the roots. On the other hand, pears do well even when the outside bark around the root-crown is blackened by the action of the alkali salts. But 38,000 pounds, even of sulfate, proves too much for the pear.

The quince appears to be materially more resistant than the apple or pear. It probably ranges alongside of the fig, the soil-adaptations of which it shares in other respects also.

The English walnut resents even a slight taint of black alkali; but is fairly tolerant of “white” salts, as is shown in the peculiarly suitable light loam soils on the lower Santa Clara river, in Ventura county, as well as in Orange county, California.

Close figures for the limits of alkali tolerance in the case of deciduous orchard trees cannot easily be given or determined, owing to the difficulties inherent in the differences of root penetration in the several soils and localities; as well as the fact already alluded to, that in close-textured soils the tolerance is in general decidedly less than in sandy lands. Hence the figures in the table must be taken as more nearly representing relative tolerances, rather than absolute data to be applied in every case. As regards the stone fruits, it should be remembered that the Myrobalan root, being at home in Asia Minor, where alkali abounds, should when practicable be used wherever alkali conditions exist, in preference to all but the almond, which seems to resist well, even on its own root, but has not as wide a range of adaptations as a grafting stock as the myrobalan. While most of the other stone fruits at the Tulare substation were on myrabalan roots, the stock of those in outside orchards was mostly in doubt. It is also to be kept in mind that different varieties of the same fruit—e. g., pears and apples—show a not inconsiderable variation in their resistance.

Timber and Shade Trees.

Of trees, forest and shade, suitable for alkali lands, some native ones call for mention. One is the California white or valley oak (Quercus lobata), which forms a dense forest of large trees on the (almost throughout somewhat alkaline) delta lands of the Kaweah River in California, and is found scatteringly all over the San Joaquin Valley. Unfortunately this tree does not supply timber valuable for aught but firewood or fence posts, being quite brittle.

The native cottonwoods, while somewhat retarded and dwarfed in their growth in strong alkali, are quite tolerant of the white salts, especially of Glauber’s salt. As they usually grow near to the water, their tolerance for alkali salts is difficult to ascertain.

Of other trees, the oriental plane, or sycamore, and the black locust have proved the most resistant in the alkali lands of the San Joaquin Valley; and the former being a very desirable shade tree, it should be widely used throughout the regions where alkali prevails more or less. The ailantus is about equally resistant, and but for the evil odor of its flowers, deserves strong commendation.

Of the eucalypts, the narrow-leaved Eucalyptus amygdalina (one of the “red gums”) and the closely related viminalis, seem to be least sensitive, and in some cases have grown in alkali lands as rapidly as anywhere. The rostrata, as well as the pink flowered variety of sideroxylon, are now doing about as well as the amygdalina at Tulare, where at first they seemed to suffer. The common blue gum, globulus, is much more sensitive.

Of the Acacias, the tall-growing A. melanoxylon (“black acacia”) resists pretty strong alkali, even on stiff soil; as can be seen at Tulare and Bakersfield, California, where there are trees nearly two feet in diameter. The beautiful A. lophantha (Albizzia) has in plantings made along the San Joaquin Valley railroad shown considerable resistance, likewise; but it is quite sensitive to frost.

Of other Australian trees, one of the Australian “pines,” (Casuarina equisetifolia), is doing well on fairly strong alkali land in the San Joaquin Valley.

A remarkably alkali-resistant shrub or small tree is the pretty Kœlreuteria paniculata from China, which at Tulare is growing in some of the strongest alkali soil of the tract. Unfortunately it is available mainly for ornamental purposes; its wood, while small, is very hard and makes excellent fuel.

Of trees indigenous to the Atlantic and East Central United States, the Tulip tree, the Linden, and most other trees of the humid region, including the English oak (Quercus pedunculata) become stunted in alkali soils. The honey locust, being particularly adapted to calcareous lands, does moderately well on alkali lands, but its thorns and imperfect shade render it not very desirable. The black locust and the elms have on the whole done best. The eastern maples are not successful; but the California maple (Acer macrophyllum) and the box elder (Negundo californica) have done fairly well in the lighter alkali lands of the San Joaquin Valley.

The Conifers—Pines, firs, cedars, cypress, etc., are very sensitive to black alkali and will not endure much even of the “white” salts. Even the native juniper of the mesas carefully adheres to the portions—breaks and upper slopes, hilltops, etc.—which are more or less leached by the scanty rains of these regions.

INDUCEMENTS TOWARD THE RECLAMATION OF ALKALI LANDS.

The expense involved in the reclamation of strong alkali lands naturally gives rise to the question whether adequate advantages are likely to be derived from such expenditure; specially when the last resort—underdraining and leaching—has to be adopted.

Those familiar with the alkali regions are aware how often the occurrence of alkali spots interrupts the continuity of fields and orchards, of which they form only a small part, but enough to mar their aspect and cultivation. Their increase and expansion under irrigation frequently renders their reclamation the only alternative of absolute abandonment of the investments and improvements made, and from that point of view alone it is of no slight practical importance. Moreover, the occurrence of vast continuous stretches of alkali lands within the otherwise most eligibly situated valley lands of the irrigation region forms a strong incentive towards their utilization.

FIG. 75.—Wheat grown on black alkali land at Tulare Substation, California, showing improvement in successive years of reclamation treatment.]

There is, however, a strong intrinsic reason pointing in the same direction, namely, the almost invariably high and lasting productiveness of these lands when once rendered available to agriculture. This is foreshadowed by the usually heavy and luxuriant growth of native plants around the margins and between alkali spots (see fig. 60); i. e., wherever the amount of injurious salts present is so small as not to interfere with the utilization of the abundant store of plant-food which, under the peculiar conditions of soil-formation in arid climates, remains in the land instead of being washed into the ocean. Extended comparative investigations of soil composition, as well as the experience of thousands of years in the oldest settled countries of the world, demonstrate this fact and show that so far from being in need of fertilization, alkali lands usually possess extraordinary productive capacity whenever freed from the injurious influence of the excess of useless salts left in the soil in consequence of deficient rainfall. (See analyses, chapter 22, pp. 436, 437).

Among many striking examples of the results of such reclamation, is that represented in the annexed figure (75), of grain grown on strong alkali land, before and after reclamation treatment. On the original land even “alkali weeds” would hardly grow; while afterward a wheat crop representing forty-two bushels per acre was grown. Additional illustrations are shown in the second figure (76), showing crops of wheat and barley as grown on partly reclaimed land at the Tulare substation.

While it is certainly true that when rightly treated, alkali lands can be rendered profusely and lastingly productive, yet close attention and constant vigilance are needed so long as the salts remain in the soil; and no one not determined to give such land such full attention, should undertake to cultivate it.

PART FOURTH.

SOILS AND NATIVE VEGETATION.