\. Ue ee ee Je | Go re ae Book ___ 0 Copyright N° COPYRIGHT DEPOSET: Nive te MU Ith ii AU : ULE ay A MDA i j aT Pe i A ale \ We ihe af “Ve aE a ie SOIL ALKALI ANV’] LIVYTY GAWIVIDAY NO GaSIVY IVaAHM Metobatets AG KR sCoUcL TUR UA Ll, S"E-R:1 ES Sort ALKALI ITS ORIGIN, NATURE, AND TREATMENT BY FRANKLIN STEWART HARRIS, Pu. D. DIRECTOR AND AGRONOMIST, UTAH AGRICULTURAL EXPERIMENT STATION, AND PROFESSOR OF AGRONOMY UTAH AGRICULTURAL COLLEGE NEW YORK JOHN WILEY & SONS, Inc. LonDON: CHAPMAN AND Hatt, Lt. 1920 COPY RIGHT* 1920 = By, FRANKLIN S. HARRIS % y 4 > es Noy “os ey . . THE PLIMPTON PRESS - NORWOOD + MASS: U:S+A — ‘, ad 4 To Dr. JOHN ANDREAS WIDTSOE PIONEER-INVESTIGATOR OF ARID AGRICULTURE, TEACHER AND FRIEND, THIS BOOK IS AFFECTIONATELY DEDICATED PREFACE Tue study of soil alkali is by no means simple, nor have all the problems relating to it been solved. The many different salts involved, each with its own properties; the various types of soils in which these salts occur, all with different textures and composition; the complex relations between the soluble salts of the soil and the plants growing on it; and the several economic factors involved in the reclamation of alkali land: these and numerous other considerations make the problems connected with soil alkali as difficult to solve as any found in agricultural science. The excuse for writing a book on a problem that is so far from solution is found in the great demand that exists for one volume containing the important information concerning alkali. At present, the literature of the sub- ject is very much scattered and is largely unavailable to the average student of soils. There are hundreds of millions of acres of land in the world that are at present not used for agriculture but which might become productive if the alkali could be eliminated. The need for more land to supply food for the world’s increasing population is making a very insistent demand that some of these alkali lands be made available. The response to this demand: will depend on a better under- standing of the nature of alkali and methods of reclaiming land impregnated with it. This accounts for the new in- terest that is being shown in the study of soil alkali. vii vill PREFACE The present volume is intended as a text and reference work for students of soils and others interested in arid agriculture. It should find wide use by county agricul- tural agents and the better trained farmers in regions where the alkali problem is encountered. References are given in connection with each chapter. The figures in parenthesis in the body of the text indicate the number of the reference at the end of the chapter. No attempt has been made to cite all the literature, but most of the important papers are included. Foreign titles have usually been translated into English in order to make them clearer to the general reader. Where the original article is likely to be unavailable an attempt has been made to refer to an abstract in some available publication such as the Experiment Station Record. The author wishes to acknowledge his indebtedness to all who have contributed either directly or indirectly to the work. He has drawn freely from all available sources, but he is particularly indebted to Dr. E. W. Hilgard and his associates in California and to the workers in the Bureau of Soils, U. S. Department of Agriculture. These two sources of information have proved to be veritable “gold mines.” The following who have read part or all of the manu- script have given many valuable suggestions: Doctors J. E. Greaves, E. G. Peterson, F. L. West, Willard Gardner, and G. R. Hill, Jr., and Professors George Stewart, O. W. Israelsen, D. W. Pittman, M. D. Thomas, Mrs. B. C. Pittman, and Mr. K. B. Sauls. The author also wishes to express his appreciation to the several assistants and co-workers who have helped in his experiments with alkali during a number of years. Without the faithful and efficient services of these men the PREFACE ix experimental work which led up to this book could not have been done. Mr. N. I. Butt deserves special mention for his help in reviewing literature and preparing the material of this book for publication. F. S. Harris Locan, UTAH November 1, 1919 Ts cate a = 7 CONTENTS CHAPTER PAGE ES UNTRODUCTORVG ats ccchorncrcls vis.c¥o. 0 als eitic elelepeteraieiaienelaretele a/0tns 3 Me GrocRAPHICAT: DISTRIBUTION: cad. sn coe Oo ne melas s op erefe @ orev 6 North America. Canada. United States. Mexico. South America. Africa. Egypt. Europe. Asia. India. Australia. TET ORIGIN ORWATICALE re-craititie < oavteie tials eles tisieieisieic stewie cece clits Composition of Soil-forming Materials. Salts from Ancient Seas. Jurassic Beds, Montana. Arms of the Ocean. Evapora- tion of Saline Lakes. Formation of Soluble Carbonates. Nitrate Formation. Concentration by Irrigation Water. Rela- tion of Origin to Methods of Treatment. IV. Nature oF ALKALI INJURY TO THE PLANT.............+4+- i Prevention of Water Absorption. Effects on Germination. Effect on Structure of the Plant. Injury at the Surface of the Soil. Me peOxIG ILTMPIS (OF ALBALI:, 2/4005. vic tect amelie Mele Vin oa o ane Siaiele Toxicity in Solution. Nutrient Solutions. Alkali Solutions. Seed Germination. Seedling Transference into Alkaline Solu- tions. Soil Results: in Sand, in Loam Soil. VI. NATIVE VEGETATION AS AN INDICATOR OF ALKALI............ How Plants Indicate the Soil. Alkali-indicating Plants: Well- defined Alkali-indicating Plants, Alkali-indicating Plants not Commonly Forming the Major Portion of Alkali-land Vegeta- tion. Discussion of Plants: Inkweed or Salt-wort, Tussock Grass (Sporobolus airoides), Kern Greasewood or Bushy Sam- phire (Allenrolfea occidentalis), Dwarf Samphire (Salicornia sublerminalis), Greasewood (Sarcobatus vermiculatus), Alkali- heath (Frankenia grandfolia campenstris), Cressa (Cressa cretica truxillensis), Salt-bush or Shadscale (Atriplex spp.), Kochia or White Sage (Kochia vestita), Salt-grass (Distichlis spicata), Other Plants. Description of Alkali-indicating Plants. xl 34 42 60 xii CONTENTS CHAPTER VII. CHEmicaAL METHops oF DETERMINING ALKALI..............- Preparing the Solution: from Moist Soil, from Dry Soil. De- termining Total Solids. Carbonate and Bicarbonate Determina- tion. Chloride Determination. Sulphate Determination. Nitrate Determination. Analytical Process. Determination of Bases: Calcium, Magnesium, Sodium. Other Methods of Determining Soluble Salts: the Electrical Bridge, Freezing-point Method, Biological Method. VIII. CHEMICAL EQUILIBRIUM AND ANTAGONISM...... ae Ghovareta shel = Solubility of Alkali Salts. Mass Action. Absorption of Salts by Soils. Equilibrium in Soil Solution. Antagonism between Alkali Salts. TX. RELATION OF ALKALI TO PHYSICAL CONDITIONS IN THE SOIL.... Changing Soil Structure. Effect of Colloids. Hardpan. Effect on Moisture Movements. Evaporation of Moisture. X. RELATION OF ALKALI TO BIOLOGICAL CONDITIONS IN THE SOIL . Relation of Soil Organisms to Fertility. Biological Inactivity and Soil Sterility. Concentrations of Alkali which Limit Biolog- ical Activities. XI. MovEMENT OF SOLUBLE SALTS THROUGH THE SOIL........... Salts in Natural Soils. Salt Movement with Water. Effect of Water-table. Movement of Various Salts. Rate of Alkali Movement. XII. MrtHops oF RECLAIMING ALKALI LANDS................00 The Source of Contamination. Reducing Evaporation. Plowing under of Surface Alkali. Removing from Surface. Neutralizing Sodium Carbonate. Other Chemical Treatments. Cropping with Alkali-resistant Crops. Drainage. OME PRACTICAT sD RSTINAGE © sieic)a. te sheen tteiey sioiene sickest mechs nian Advantages of Drainage. Determining the Need of Drainage. Types of Drains. Cement Tile for Alkali Land: Preliminary Survey, Laying out the System, Size of Drains, Construction Methods. Outlets and Silt Basins. Cost of Drainage. SAV CROPSSROR: AT KATH SUAND Sire cise ote ae eo ee Factors Affecting Resistance. Economic Factors Affecting Choice. Tolerance of Alkali by Various Crops; Forage Crops, 105 119 141 154 167 192 CONTENTS xiii CHAPTER PAGE XIV (continued) Alfalfa, Sweet Clover (Melilotus alba and M. officinalis). Other Clovers: Vetch (Vicia saliva and V. villosa), Field Peas (Pisum sativum), Beans. Grasses: Timothy, Orchard Grass (Dactylis glomerata), Brome Grass (Bromus inermis), Red Top (A gnostis alba), Blueg ass (Poa pratensis), Western Wheat Grass (A gropy- ron), Japanese Wheat Grass (Agropyron Japonicum), Rye Grass, Fescue, Tall Meadow Oat-grass (Arrhenatherum elatins), Wild or Native Grasses, Salt Grass (Distichlis spicata), Bluestem Grass (Agropyron Occidentale), Tussock Grass or Purple Top (Sporo- bolus airoides), Alkali Meadow Grass (Puccinellia airoides), Prairie Grasses, Modiola (Modiola procumbens), Salt Bushes (Atriplex spp.), Giant Rye Grass (Elymus condensatus), Sedges and Rushes, Millets, Sorghums, Rape (Brassica napus and B. oleracea). Grain Crops: Wheat, Barley, Oats, Rye, Corn, Rice, Emmer, Sunflowers. Root and Vegetable Crops: Sugar-beets, Potatoes, Onions, Asparagus, Celery, Radishes, other Vegetables. Fiber Crops: Flax, Cotton. ‘Trees and Shrubs: Fruit Trees and Shrubs, Date Palms, Grapes, Olives, Other Fruits, Other Trees. MOV MATICADT VWATERT FOR RRTGATION (rss s.clan cisies Gieteicieie sis ciaiers.o. 6 224 Sources of Contamination. Observed Toxic Limits. Compo- sition of Typical Alkali Waters. Factors Modifying Toxic Limits of Salt. ENO DGIN GMAT AT Ie L7AININs rs Src te lots ichagss Pelartnere, sxehelate ie vore’sls,e shaterelale 240 Geology of Region. General Appearance. Native Vegetation. The Water-table. Analysis of the Soil. Possibility of Reclama- tion. Economic Factors. ‘_ yt? ¥. > Pu lt ore ae B! " ‘ wd Kes Geen if - a : heyy Tey Per ny Prise J i Aid Bik, 4 : a sie PIG. - Bes LIST OF ILLUSTRATIONS vt PAGE Wheat Raised on Reclaimed Alkali Land... .. Frontis piece eEOa- Heating Suale EOLMAtION! (34 f2c).st snes os es « 24 wp MT SISA) YEON Ur Aaa ee ka a 26 Wormmaland Plasmolyzed Cells. 325.02. oss. s aes: 35 An Orchard Planted on Land that Came from a Formation High in Soluble Salts. Seer a7 . The Lower Part of an Orchard ie Killed by Alkali brought to the Surface by a Rising Water Table.. 39 . Experiments to Determine. the Toxicity of Various PRS EU EEL GE Yoo) oc! 2 £5 ek nea gS REDE Jose 50 . Growth of Wheat with Various Concentrations of WOR CE DE SALES csi ons ePoetel ee entrees I teRN Og 54 . Alkali Crusts at the Surface Preventing the Growth of Practically all Vegetation...... 61 . Alkali Land which is Indicated ae an ican of SLING RSET FREE sen nS RU Le ge ON ae 62 Greasewood and: Shadscale 32. cu.¢.6 ec ce os. eee 66 . The Border between Greasewood and Salt Grass.... 68 . The Last Plant to Abandon an Alkali Flat......... 71 . Plants Growing at the Top of Sand Dunes......... 74 . Determining Soluble Salts with the Electric Bridge PEI ETE LGD. = 37 oc co eR RE elec nS TTS ceed 102 . Alkali Coming to the Surface where Seepage Water from a Canal Comes to the Surface and Evaporates 110 XV Xvi TOE 7s 18. 19. 20. 2I. P}PA 23% 24. 25. 206. Aye 28. 29. 30. a1. a2. 33- ILLUSTRATIONS Black Alkali Crust Forming where the Land has been Cultivated Land that had to be Abandoned because of the Rise.of Alkali. . 2. io Ase eee Alkali Hating away the Fence Posts =-222--)) ee Typical Hard Pan Found in Arid Soils... 0 5..... Field Ready for Layimg Tile 25 ieee eee Boggy Alkali Land that is Difficult to Drain with Short, Wile:.\. . 0.2... eee eben Open Ditch used to Carry away the Drainage Water from. a-Uarce pAtears aon Machine for Making Drains in Heavy Soil without the’ Use: of STile.t:) .28525 20-0 Geen eee aoe Poorly Made Cement that is being Crumbled by AMC, 2 Fe eae RI eee ee a Method of Establishing Grade of Drains........... Types of Lumber Drains used to Reclaim Boggy Allealis Mand. 7. 2ovir 2c ste eae en eee Wood Drains being used to Drain Boggy Alkali Land Drainage Machine with Digging Wheel above the” Ground... fsa ee Drainage Machine with Digging Wheel in the Trench Silt Box with Lid. The Silt that Settles in the Box can be Spaded'Outacce s ee eee eee Alkali Spot inva (Gram) Fielder ese eer The More Tender Trees are being Killed with Rising Alkah, while Alfalfa is Still Unaffected.......... Layer of Alkali Several Feet below the Surface..... II5 143 147 156 168 175 184 SOIL ALKALI SOIL ALKALI CHAPTER I INTRODUCTORY WHENEVER the word “alkali”? is mentioned there im- mediately arises in the minds of some people a vision of desolation. They may picture to themselves a_ barren tract of land devoid of vegetation and covered with a blanket of white salt mixed with earth; or they may fancy that they see worthless wastes of what had been fertile fields. They imagine beautiful trees being reduced to stumps and fence posts and remnants of farm buildings gradually being eaten away by a slowly advancing white cover, which will eventually reduce the entire landscape to a gray barrenness. Probably each of these pictures has a prototype in some local section. Alkali does prevent the cultivation of vast areas of land, and it has caused the abandonment of many fertile fields; but to give up all effort when alkali makes its appearance would be like abandoning a farm just because some crop became in- fested with a pest. The successful pursuit of agriculture calls for the con- stant overcoming of difficulties. New problems arise each season, but success demands that these be solved. The difference between civilization and savagery consists largely in meeting difficulties and being masters of nature instead of merely victims of circumstance. 3 4 INTRODUCTORY The welfare of the entire people is dependent on the prosperity of agriculture, and in turn agriculture rests on the productivity of the soil. Human well-being is therefore closely tied up with the land. Whatever affects agricul- ture is important not only to the tillers of the soil but to all who consume the products of the farm. In order that an ample food-supply may be assured at a low price, the people generally are interested in having available as large a producing area as possible. Most of the more desirable lands of the world have been settled. This means that an extension of the area of pro- duction will often necessitate the use of land that has some unfavorable condition. There are in the world vast tracts that are not susceptible of cultivation without special treatment. In the arid parts of the earth, which comprise about one-half of the total land, two great conditions are withholding from cultivation millions of acres of land. They are drouth and alkali. The successful overcoming of drouth and alkali means the addition of countless acres to the productive part of the earth. It is with alkali and its conquest that the present volume deals. It has been estimated that about 13 per cent of the irrigated land of the United States contains sufficient alkali to be harmful. This means that there are over nine million acres of land under present canal systems that are affected with alkali. There are many more million acres of alkali land in the United States that do not lie under irrigation systems. Similar figures might also be given for other countries of this continent and for all of the other continents. The alkali problem is one of no mean importance to farmers, nor to any who are interested in the world’s food-supply. In a strictly chemical sense the word “alkali” refers INTRODUCTORY 5 to a substance having a basic reaction. As applied to the soil, however, this restricted meaning does not hold, and alkali refers to any soluble salts that make the soil solution sufficiently concentrated to injure plants. This includes the chlorides, sulphates, carbonates, and nitrates of sodium, potassium, and magnesium, and the chloride and nitrate of calcium. The sulphate and carbonate of calcium are not sufficiently soluble to be injurious to crops. Most of the alkalies are in reality neutral salts. It may be some- what unfortunate to use for general substances a word that also has a restricted technical meaning, but the word has become so well established in agricultural literature that it would now be very difficult to change it. Aside from their practical importance, the soluble salts of the soil are of great scientific interest. They offer fruitful fields for investigation to the geologist, the chemist, the plant physiologist, the bacteriologist, the mycologist, the agronomist, and the engineer. The complexity of the soil makes the problems connected with alkali very difficult to.solve. There are so many interacting factors that no simple statement of the problem can be made and no simple solution arrived at. A complete under- standing of the problem will call for careful researches by investigators in different branches of science and a careful coordination of the findings. The importance of the subject justifies giving it the most careful consideration. CHAPTER. Tf GEOGRAPHICAL DISTRIBUTION SOILs containing injurious quantities of alkali are found on every continent. These soils, however, do not occur in all parts of the continents, the distribution being con- fined to areas where conditions favorable to their formation prevail. The most important of these conditions is aridity. Another important factor is the nature of the rock from which the soils were formed. Because these conditions are local, alkali soils are likely to be found over large areas, but all the soils of these areas are not necessarily highly charged with soluble salts. Part of the soils in a region having a climate favorable to alkali formation may be derived from rocks that are low in soluble salts and may have been so deposited that they have good natural drain- age. Soils of this kind do not contain alkali even though most of the soils of the region are impregnated. Likewise, soils high in soluble salts may be found over limited areas in regions where most of the soils are free. This condition is sometimes found in climates that are not entirely arid, or where a soil having poor drainage was derived from rock that was high in soluble salts. Thus, the alkali problem has local as well as general aspects. A general alkali condition may prevail over an extensive region, the smaller areas of which may be exceedingly variable. North America. More than half of the North-Ameri- can continent is arid or semi-arid. Throughout this vast area alkali soils are found. There are many large tracts 6 CANADA 7 in which the soluble salt content of the soil is not at present sufficient to interfere with crop growth, but there is suffi- cient of the salts present if concentrated by unwise methods of irrigation, by drouth, or by other means to bring the soil to the danger point, especially should drainage be poor. The tooth meridian may be taken roughly as the line separating the humid from the arid part of the continent. This line is not absolute; it varies somewhat with latitude, altitude, and several other factors. There are a number of places west of this line where the rainfall is high. This is particularly true along the northwest coast and along some of the mountain ranges. Canada. — In western Canada, especially in the prov- inces of Saskatchewan, Alberta, and British Columbia, there are several rather large tracts where the soluble- salt content of the soil is sufficiently high to render crop production difficult. In southeastern Alberta the soil of one of these regions originated from the glaciation of shale that was high in soluble salts, particularly the sulphates. Therefore, sulphates are the predominating salt of the region. The soil is heavy and impervious; consequently, there has been very little movement of salts from its original place in the soils. Under irrigation these salts may be either leached down- ward or brought to the surface. When appearing as a white inflorescence they are very conspicuous and would lead the casual observer to believe the condition to be much worse than it really is. A large quantity of gypsum is present in these soils and, when dissolved and brought to the surface, it, together with sodium sulphate, forms a conspicuous white soil covering. Fortunately, the percentage of the more harmful chlorides and carbonates is very low. ok GEOGRAPHICAL DISTRIBUTION The composition of an alkali soil in Alberta as determined by Shutt (16) is given in the following table. TABLE I. SOLUBLE SALTS IN ALKALI SoIL OF ALBERTA, CANADA (PER CENT) ae Growth | NazSOs MgSO: CaSOx Te ee ©.0-0.5 O.5-1-5 Good .178 087 163 440 T5230 .877 132 -447 TeS72 3.0-5.0 -973 563 2.926 640 BxO—5O Poor 2123 SRP dame era 180 701 247 -491 1.480 719 309 .588 1.680 799 062 .192 I.060 3.0-5.0 No TAyAT Melero) .648 3.260 I.OOT 323 . 364 I.700 701 222 .220 I.164 579 084 -192 goo United States. — In sixteen or seventeen of the western states of the Union, alkali is found to be one of the chief agricultural problems. ‘The problem is much more acute in some regions than others. The San Joaquin, Sacra- mento, and Imperial Valleys of California; the Great Basin, comprising a large part of Utah and Nevada; the Colorado River drainage basin, comprising parts of Wyoming, Utah, Colorado, Arizona, and California; the Rio Grande River drainage area, including parts of New Mexico and Texas; parts of the Columbia River drainage basin; and rather extensive sections in the Great Plains east of the Rocky Mountains include the most important parts of the United States affected with alkali. In practically all the western states certain areas affected by alkali have been described in publications of the state MEXICO 9 experiment stations or in the United States Bureau of Soils. (See Table II.) These publications show that the composition of the alkali salts as well as the methods of reclamation vary greatly. TaBLe II. ComposITION OF ALKALI FROM DIFFERENT PARTS OF THE UNITED STATES EXPRESSED IN PERCENTAGE OF DIFFERENT SALTS PERCENTAGE OF DIFFERENT SALTS IN THE ALKALI Salts Montana‘ Arizona5 Colorado! | California? bide = — Crust pata Crust Jo-72 in. IGE eis Soa. TROA Penge. SAO eerie Ihe 4.00 | 22.10 BESO nese nico: BOS: eee TE GOja| Qe Awe cage shal pecs LSG{ OLS at esate Ii ae same ae (a) tal ane ete tel La Sens cre cod lover eae || nee ae NaS Opel sate ias ites Alco yeveallt ipooe SEG) ab eG eliza |e mey secs tects INGINO Soke BALOT ANE TON 7S «(| ohare -)oce lt ey ere eel aeen aan eet | cs nae ING © Osea remain irot ts BOe08 niles OOn | merpae LSC Ale Be cas ta | echo NaCl cise: (ere alo G wall! Bes 56 OSS Sil Mase Hea lisy || earedh afr NasHPO, Rene of oh otal [erst cis: ccs PAO AC yaa Wea cape. 2} | aoe Gone |s orctcanae elena oho lotta ora INESTOVe' = Se eia tas cseed tapers inesiee 8.90 AOOl ea cee 6.88 MeGls ns 3). TOV Tolle eat Basa los ica set |Pasgereks clip ska eats Hue Al Ghaeys) (CHG Aer ASLO PE th aii earnest Pa haere teal ey Stove CRAG team INGG IC OS aE an | eeeecaeied |Meat 36.72 0.67 | 22.06 | 0.28 | 21.02 CaSO. x. Hitey ty || Goroe 1.87 Dale || Uuerfoy) |) KOs Oe | BAAS Ca(HCOs)2. eaten ella tsetelonie) | MMivieiiels,'« 16.48 Seer ei sree) ctiehe |. tar eveyone. ll Nera rerets NICE COs) peisi2 |e ecco ||) oe ae nAfes FMA be eae ci ty ie ee eR eet P ace (NH,4)sCOs. pike me el IP wane! a's Pa 1 2 Wh eeprom) as oes Fo NAS catecr, tol heen eet [Awe ye Mexico.— The greater part of the high plateau of Mexico has an arid climate. This, like all similar regions, has had but comparatively little of the soluble salts contained in the country rock removed. In this section there are many large valleys having no outlets. During 1 Colorado Exp. Sta., Bul. 155, p. 10. 2 Hilgard “Soils,” p. 442. = USS, D. A; Bur. cous bul35: p:70; 4 U.S. D. A. Bur. Soils, Bul. 35, p. 103. 6 U.S. D. A. Bur. Soils, Bul. 35, p. 109. 10 GEOGRAPHICAL DISTRIBUTION the rainy season the lower parts of these valleys are flooded by the waters of swollen streams; during the dry season this water is practically all evaporated, leaving its soluble material behind. This results in great level bodies of land charged in varying degrees with soluble salts. The composition of these saline deposits depends on the com- position of the country rock through which the streams flow. Very little work up to the present time has been done to reclaim the alkali soils of Mexico. South America.— No important published material is available on the alkali condition of the soils of South America. It is known, however, that the arid sections of that continent do not differ essentially from those of other arid sections of the world. Practically the entire western part of the continent is arid and throughout this section areas subject to alkali troubles are found. It includes most of the Pacific slope west of the Andes and the greater part of the western plains of Brazil and Argentina east of these mountains. The deposits of sodium nitrate in Chile are a conspicuous example of the retention of soluble salts that would be leached out in a humid climate. Africa.— The distribution of alkali soils in Africa is not the same as in North and South America. It is found over practically the entire northern portion of the con- tinent and also in the southwestern part. The central, and particularly the west-central, portion is practically free. Throughout the Union of South Africa up into Rhodesia alkali soils are found but have not received as much attention as some of the sections of North Africa, particularly in Egypt. The soils of the Sahara as well as many of those of Algeria, Morocco, and Tunis are so contaminated with soluble salts that it was necessary for EGYPT 11 the agriculture of these countries to be adjusted to this condition. It is probable that the alkali problem is being given more consideration in Egypt than elsewhere. Egypt.— The greater part of Egypt is a barren desert, being one of the most desolate parts of the earth. The an- nual precipitation at Alexandria averages 8.26 inches; at Port Said, 3.49 inches; and at Cairo it is only 1.06 inches, which is not enough to support vegetation of any kind. The country is traversed from south to north by the Nile River along which is a narrow, highly cultivated, and thickly populated strip of river-formed land. In the southern part of the country the river flows through sand- stone and occupies a shallow valley, but farther north a deep gorge is cut down from the surrounding limestone plateau. On both sides of the river are alluvial plains composed of fine silt which for the most part has been carried by the Nile from the disintegrated volcanic material of the Abyssinian highlands. Thus the soil of the lower Nile Valley bears no relation to the country rock of the immediate vicinity. In the delta portion of the valley, the land is very flat and there is but little opportunity for drainage. Much land that was cultivated anciently has since been abandoned on account of the accumulation of alkali. The area thus abandoned has been estimated to be more than one and a half million acres. Most of this land is on the fringe that borders the sea and is influenced by sea water. The higher lands are practically free from alkali. Formerly all the land was watered by the basin system of irrigation. With this method, the land is flooded to a depth of from three to five feet at the season when the Nile is high. After standing at this depth for about six weeks and allowing the sediment to settle, the water is drained 12 GEOGRAPHICAL DISTRIBUTION back into the Nile, and the crops are planted in the mud without plowing. By this system only one crop is grown each year, but the accumulation of alkali is prevented by washing part of it to lower depths in the soil, by depositing a fresh layer of salt-free silt on the surface, and by carrying away with the water that is drained off any soluble material that may have accumulated on the surface at the time of flooding. In order to raise more than one crop a year and thereby get greater profit from the land, the basin system of irri- gation is being largely supplanted by the perennial system, by means of which water is applied throughout the year. This brings about almost continuous evaporation from the surface and a consequent accumulation of soluble salts. Of .the 6,250,000 acres of irrigable land in Egypt, only about 1,730,000 acres are irrigated by the old system of basin irrigation. This means that the alkali problem will continue to be more acute in Egypt until suitable means of coping with it are worked out. Already some rather ingenious methods (23, 25) of drainage are in operation. The following analysis reported by Means (14) of an alkali soil from Kom-el-Akhdar is typical of the alkali land of lower Egypt: TABLE III. CuHrEmMIcAL ANALYSIS OF ALKALI SOIL FROM KOM-EL- AKHDAR, Ecypt (Surface foot) Tons Per cent Conventional Combinations Per cent (Chienonan (Ca)s a. 6 co00 be 3.07 | Calcium Sulphate (CaSO,). ... | 10.43 Magnesium (Mg)....... 2.00| Magnesium Sulphate (MgSOu,) 9.90 Sodiume@Na) hee seas 28.83 | Potassium Chloride (KCl) .... 3702 losin (IK ))o oo dbs ac 1.90 | Sodium Chloride (NaCl) ...... 60.88 Sulphuric Acid (SO,).... 56 | Sodium Bicarbonate (NaHCO;) | 1.41 24. Chlormne(C))\ 38.62 | Sodium Sulphate (NaySO,).... | 13.76 Bicarbonate Acid (HCOs) | 1.02 Per cent Soluble. ........ 8.2 INDIA is Europe.— Of all the continents, Europe is the most free from alkali, although it has several alkali sections. Probably the most conspicuous of these is found in Hun- gary. The “Szik ” lands of the plains contain some soluble salts and lower down in the valley of the Theiss genuine alkali lands are found with a high content of both white and black alkali. From these lands carbonate of soda has long been obtained commercially. In the lower valley of the Po in Italy (2) and in many other sections of Europe bordering the Mediterranean local alkali areas are found. i Asia. — The main alkali regions of Asia are found in the central and southwestern portions of the continent. Arabia, Mesopotamia, Persia, Afghanistan, Baluchistan, ’ Turkestan, and Northern India are all more or less affected with alkali salts. In some of these countries agriculture has continued in spite of the excess of soluble salts because special methods have been devised as a result of experience extending back to prehistoric times. Modern investigations of alkali have been more complete in India than in other parts of Asia; consequently, more attention will be given to that country in the present discussion. India. — The alkali, or veh, lands of India were first investigated by the “Reh Commission” about 1876. This commission was appointed to discover the cause of deterioration of some of the lands that had previously been fertile. Since that time the various experiment stations in India have made more extensive investigations. They have shown that “usar” lands (12) exist largely not only in the northwestern provinces and Oudh, but also in the Punjab, especially on lands bordering the Chenab River, likewise to a slight extent in the Bombay Presidency. 14 GEOGRAPHICAL DISTRIBUTION The Reh Commission brought out the fact that under the ancient systems of agriculture in India there was very little increase in the amount of soluble salts at the surface, but with the construction of large modern canals and the application of unnecessarily large quantities of irrigation water the increase in alkali was very rapid. Leather (12) has pointed out that not all the lands called by the natives “usar ” owe their infertility to alkali. Some simply have very hard clay soils which are difficult to bring into a good state of tilth. The true “reh” lands, however, are like the alkali lands of other parts of the world. Australia. — The greater part of Australia may be con- sidered as arid although the rainfall of the eastern part of the continent is high. During the last generation large irrigation works have been constructed and vast tracts of land containing a rather high content of soluble salts have been brought under cultivation. In such sections alkali is one of the serious problems. Alkali conditions in Aus- tralia are somewhat similar to those of the western part of the United States. REFERENCES 1. Amrs, J. W. Some Alkali Soils in Ohio. Ohio Sta. Mo. Bul. 1 (1916), No. 7, pp. 209-210. 2. Arti, R. A Saline Soil of the Lower Valley of the Po (Italy). Accad. Econ. Agr. Firenze, 5, Ser. 3 (1906), No. 1, pp. 59-64. (Abs. E. S. IRS shy Je Diss) 3. Bancrort, R. L. The Alkali Soils of Iowa. Iowa Sta. Bul. 177 (1918), pp. 185, 208. 4. Burp, J. S. Alkali Conditions in the Payette Valley. Idaho Sta. Bul. 51 (1905), pp. 1-20. 5. CrarRKE, F. W. The Data of Geochemistry. U. S. Geol. Survey, Bul. 616 (1916), pp. 143-167 and 206-247. 6. DEAKIN, ALFRED. Irrigated India, 322 pp. (London, 1893.) 10. II. 12. 10. 17; 18. 19. 20. 2I. 22. oa. 24. 25. REFERENCES LS . Druo, N. A. Influence of Irrigation and of Increased Natural Hu- midity on the Process of Salt Formation and of the Transportation of Salts in the Soils and Subsoils of Golodnoi (Hungary) Steppe, Smarkand Province. Russ. Jour. Exp. Landw. 15 (1914), No. 2, pp. 336-338. (Abs. E. S. R. 34, p. 16.) Hepert, A. Alkali Soils from the Knee of the Niger River. Bul. Soc. Chim., France, 4, Ser. 9 (1911), Nos. 16, 17, pp. 842-843. Hircarp, E. W. Soils, pp. 423-424. (New York, 1906.) Hitt, E. G. The Analysis of Reh, the Alkali Salts in Indian Usar Land. Proc. Chem. Soc., London, 19 (1903), No. 262, pp. 58-61. (Abs. E. S. R. 14, p. 1056.) KEARNEY, T. H., and Means, T. H. Crops Used in the Reclamation of Alkali Lands in Egypt. U.S. D. A. Yearbook (1902), pp. 573-588. LEATHER, J. W. Investigation of Usar Land in the United Provinces, Allahabad, India. Govt., 1914, pp. 88. (E. S. R. 33, p. 419.) . Mann, H.H., and Tamnane, V. A. The Salt Lands of the Nira Valley (India). Dept. of Agr., Bombay, Bul. 39, 35 pp. . Means, T. H. Reclamation of Alkali Lands in Egypt. U.S. D. A. Bur. of Soils, Bul. 21 (1903), 48 pp. . MacOwan, P. Black Land in Relation to Irrigation and Drainage, Agr. Jour. Cape Good Hope, 23 (1903), No. 5, pp. 573-581. Suutt, F. T. and Smith, E. A. The Alkali Content of Soils as Related to Crop Growth. Trans. Roy. Soc. Can. Ser. 3 (1918), Vol. 12, pp. 83-97. Sicmonp, A. von. On the Types of “Szik” Soils of the Hungarian Alféld. Foldtani Kézlony, 36 (1906), No. 10-12, pp. 439-454. (Ais. B.S: Rio, op. 1Lr7.) Snow, F. J., Hitcarp, E. W.,and SHaw, G. W. Lands of the Colorado Delta in the Salton Basin. Cal. Sta. Bul. 140 (1902), pp. 51. STEVENSON, W. H., and Brown, P. E. Improving Iowa’s Peat and Alkali Soils. Iowa Sta. Bul. 157 (1915), pp. 45-70. TRAPHAGEN, F. W. The Alkali Soils of Montana. Mont. Sta. Bul. 18 (1898), pp. 50. Turarxov, N. Soils of the Kirghiz Steppe. Russ. Jour. Exp. Landw. 9 (1908), pp. 628-630. (Abs. E. S. R. 22, p. 617.) Vissotski1, G. The Soil Zones of European Russia in Connection with the Salt Content of the Subsoils and with the Character of the Forest Vegetation. Pochvovedenie (Pedologie), 1 (1899), pp. 19-26. (Abs. E: S. R. 12, p. 025.) Wittcocks, W. Egyptian Irrigation, 485 pp. (London and New York, 1890.) Wittcocks, W. The Irrigation of Mesopotamia. (London and New York, ro1t.) Wittcocks, W. The Nile in 1904, 225 pp. (London, 1904.) CHAPTER III THE ORIGIN OF ALKALI THE presence of alkali incrustations over the surface of the soil was observed long before scientists were able to account for the origin of these salts. This led to quite a number of theories regarding the source of the alkali. Several of the early theories have been found untenable in the light of later investigation. Many of the formerly obscure facts are now definitely known and there is a much clearer idea of the source of the soluble salts of the soil; but even today considerable difference of opinion exists regarding the origin of some of these salts. More data must be gathered before it will be possible to state definitely why certain deposits of alkali occupy their present position and maintain their present composition. It is definitely known that there are a number of distinct conditions promoting the accumulations of alkali in various sections. TaBLe IV. AvERAGE CoMmposITION OF IGNEOUS RocKS, SHALE, AND SANDSTONE (PER CENT) Igneous Rocks Shale Sandstone (OMEN Aah aon mee a sels eee se 12.0 Dp) 8 elds paltsweewacsteeycieesiersicvene rhe 59.5 30.0 TEL Hornblende and pyroxene... . 16.8 BY ve IMI Gabepraeerreer et icy. Shercus trent, 3.8 cote 4.é (CHER: ata a tsglo See eee eine ree 25.0 6.6 WimMOMIte Wace cooses Aes 5-6 1.8 Garbonatesapcei ia ieee ise ae Bay) Titer Othermineralse ieee eee.- 7.9 II.4 2.2 COMPOSITION OF SOIL-FORMING MATERIALS 17 Composition of Soil-forming Materials. — There seems to be no doubt that the soluble salts of the soils have come from the same materials as the soils. The exact chemical reactions that have brought about these changes and the methods of concentrating the soluble constituents are, however, not so well known. The materials composing the soil have been derived largely from the rocks and minerals which constitute the crust of the earth, together with a greater or lesser quantity of organic matter coming from the dead bod ies of plants. TABLE V. AVERAGE COMPOSITION OF THE LITHOSPHERE Tenens Shale Sandstone Limestone Weichte (95 ee cent) (4 per cent) (0-75 Der aS Meee SiO» 59.83 58.10 78.33 5-19 59-77 ASQ say sore co: 14.98 15.40 4.77 .8I 14.89 HesOstrnue eis Als 4.02 it eV) 54 2.69 1S BS ee 3.40 2.45 AOI ellis ese sts 3-39 IMPOR ae ac B5Or 2.44 1.16 7.89 3.74 (CA Oe ae 4.84 Bern Sie) A2ASy, 4.86 INE OM oiade 3.36 1.30 -45 05 B25 1S OR sone 2.99 3.24 Best 33 2.98 LEO eieisic 1.89 5.00 1.63 77 2502 MIOg os. ais: 78 65 a2 06 77 i Oe aee OD ir Othiet A Are aed | eee Peer ie Wy [le cases, o2 (ClO oats 48 2.63 5.03 41.54 70 P20; 29 a7 c8 04 28 SOG ep RES II ety fan Sere fore) 10 SO tee, stereos 64 07 05 03 Gla A Sater: (2) he 4 [ee a eae [op 02 06 Be aerate. Oi ee Ml boa Lr one st] Nant cepharersee || see ca alte fore) 1341 OS eroveneie .10 05 OSI MILE. aetoae fore) LOM ars coe RCC) ie el ae eA Amst 2 | Ale ae ye 04 Nin Oa Rac ETO yn SMe estes lla hept ce the 05 og PIG in es oP rill Maem ne. alley Rotde ast el | eo ee 025 CrO3. . Holst Reta DM cetera | [igsciy crit Gara hile |. Saat oar Rabe 05 Ve@aete ots Soy Animal Mba teeaa eee al egies Bars toast || 7 bare 025 EO: .. S(chigl by Mer eee ee rot Mee AA a aie Ree Or Coreen eoetae tealigy stereo oss OOM, | earetes vsbeiate hewn Sete, to 03 100.000 I00 .00 100.00 100.00 100.000 18 THE ORIGIN OF ALKALI Compilations made by Clarke (6) show the earth’s crust to be made up largely of the important minerals shown in Table IV (page 16). On the basis of the composition and relative amount of the different rocks he computes the average composition of the earth’s crust as shown in Table V (page 17). Clarke (6) gives the composition of the ocean waters as follows: TABLE VI. COMPOSITION OF OCEAN WATER Salts Per cent Elements Per cent Sodium Chloride (NaCl)....... TiO Oxy centres 85.79 Magnesium Chloride (MgClz) ... 10.88 Hydrogen.... 10.67 Magnesium Sulphate (MgSO). . 4.74 Chionnes- ee 2.07 Calcium Sulphate (CaSO,)...... 3.60 SOGIuUMee ae 1.14 Potassium Sulphate (K2SO,).. .. 2.46 Magnesium... .14 Magnesium Bromide (MgBry)... 522 Calciumayee .05 Calcium Carbonate (CaCOs;).... 34 Potassium. ... 04 Sulphur...... 09 Bromine..... .008 Carbonees-e .002 100.00 100.00 He reports a maximum salinity of 37.37 grams of salts to a kilogram of water, or 3.737 per cent with an average of about 3.5 per cent. These figures give a general idea of the materials from which soils are made and the substances which have been leached from them. In order to determine soluble matter that might be washed from rocks and minerals of various kinds, Whitney and Means (23) compiled the material contained in Table VII from the writings of G. P. Merrill. This table gives an idea of the material that is usually washed from rocks and minerals of different kinds in the COMPOSITION OF SOIL-FORMING MATERIALS 19 Taste VII. Amount OF SOLUBLE MATTER REMOVED IN THE DrCOMPOSITION OF ROCKS AND THE FORMATION OF SOILS Rock REMOVED BY SOLU- TION FROM Eacn ACRE- Kind of Rock Locality ABOE OE Ort. FORMED Per cent Tons Granite District of Columbia 13 261 Gneiss Virginia 45 1,431 Syenite Arkansas 50 2.227 Phenolite Bohemia ie) 195 Diabase Massachusetts 15 309 Diabase Venezuela 40 1,166 Basalt Bohemia 44 1,376 Basalt France 60 2,625 Diorite Virginia 38 1,072 Soapstone Maryland 52 1,895 Soapstone Virginia 78 6,204 Limestone Arkansas 98 85,760 formation of soils. Dissolved material may be washed to the sea or into lakes, or it may simply be transferred to lower lying soil and there often concentrated so highly that it becomes injurious to plant growth. Some of these dissolved materials, such as limestone, are not sufficiently soluble to be troublesome even in the highest possible concentrations. TABLE VIII. PERCENTAGE OF ALKALIES IN VARIOUS SOIL- FORMING MINERALS Teldspars eeeanes Micas SA Tkalies Orthoclase-). 5S s240 2: 17 Miuscoviten:2..-2..- 12 Macroliness.< seen c<- 17 BIO tte enyosis ers fuss cre ie) IAI DIte tree ee vas 2 ie 12 Bhigzopitess-.. snes. 9 Mlioclases 3Ai. ce yt: ) Nepheline: .. 2.5.5). 0% 2/ Andesite. 27) elie. ts 8 IEGUGbe pry tne eno Dit Js Wabradorites. ote... 4 bytownite. 2522 cs « Bn ET aUVME aos Aisi Messi 17 AGTOLENILES © seers, ies oe 2 20 THE ORIGIN OF ALKALI The same authors (23) give a list of alkali-bearing min- erals occurring in primary rocks as the ultimate source of soil alkali. “Some of these alkali-bearing minerals are very generally present in the primary rocks from which the soils have all ultimately been derived, but they are of course usually mixed with other minerals, so that the total percentage of alkalies in the rock is not so great as would appear from these minerals.” As to the method of separating these soluble substances and transferring them to the surface, Cameron suggested a hypothesis which is quoted by Dorsey (7) as follows: “The major part of the complex crystalline masses or of rocks forming the earth’s crust contain chlorine and sulphur. F. W. Clarke gives as an average 0.07 per cent chlorine and o.108 per cent sulphur. As a result of the hydrolyzing action of water and other decomposing agencies probably all the chlorine and very much of the sulphur is converted into hydrochloric acid and sulphuric acid, which in turn form the corresponding salts of the alkalies and alkaline earths. The aggregate amount which is thus being constantly formed in the subsoils and under- lying strata of any one area must be very large. As evaporation proceeds at or in the surface soil, there is a rise of the water in the underlying layers through the capillary spaces toward the surface, bringing with it the hydrochloric and sulphuric acids or their salts. “The sulphuric acid moves up more slowly than does the hydrochloric acid; partly, perhaps, because the rock masses and the soils have a greater absorbing action on sulphuric than on hydrochloric acid, tending to withdraw it from solution; partly, perhaps, because reducing con- ditions may exist on some layers tending to the formation COMPOSITION OF SOIL-FORMING MATERIALS 21 of metallic sulphides; and, partly, undoubtedly, to the formation of the slightly soluble calcium sulphate. This last, however, is gradually brought toward the surface, and is often found in enormous masses at moderate depths in the soils of arid regions. Undoubtedly the calcium carbonate so generally found in large masses at moderate depths in the soil of arid regions originates in a similar manner. “Hydrochloric acid is transported through soils and most absorbing media with comparative ease. Moreover the chlorides of the alkalies and alkaline earths are readily soluble. Chlorides should be expected, therefore, to accumulate in preponderant masses at the surface, which under arid and semi-arid conditions they generally do. “The preponderance of sodium chloride above other chlorides is readily explicable. It is well known that when solutions of chlorides are poured through columns of soil or similar substances, offering a large surface of contact to the solution, there is a well-marked selective absorption, the soil tending to withdraw the base from the solution to a decidedly greater extent than the acid, with the result that the leaching generally contains free acid. So far as the experience we have goes, it would seem that, in general, soils absorb potassium most readily, then magnesium, calcium, and sodium in the order named. Supposing the hydrochloric acid when found in the lower layers to be neutralized with a mixture of these bases, as it rises in the capillary movement, there is always a tendency, owing to the selective absorption of the soil, toward a lagging behind of the potassium, a lesser lagging of the magnesium and calcium (these bases probably tending also to form the much less soluble sulphates and carbonates) and a much less lagging of the sodium. In consequence, sodium Dd THE ORIGIN OF ALKALI is the predominating base in the readily soluble salts at the surface.” This hypothesis does not explain the method of accumu- lation of alkali at certain places in the soil; it merely attempts to show why certain salts are present at the sur- face in larger quantities than others. Salts from Ancient Seas. — The observation that alkali is found in large quantities in one section, whereas it may be almost entirely lacking in another section of sim- ilar climatic conditions early led to an attempt to trace the salt to the rock from which the soil was formed. Traphagen (21), at the suggestion of W. H. Weed of the U.S. Geological Survey, made a comparison of the composi- tion of the alkali near Billings, Montana, with the soluble salts in the Fort Benton shales from which the soils were in part derived. As a result of this study he was led to the conclusion that in this case the soluble salts in the soil resulted from a transference of the salts to the soil while the shale was being disintegrated. This theory was afterward supported by the work of Whitney and Means (23) in the same region. Cameron (4) also mentions shale and similar deposits as a source of alkalies. It seems, however, to have been left for Stewart, Peter- son, and Greaves (17, 16, 19, 18) to explain clearly the intimate relation existing between present alkali accu- mulations and the presence of large quantities of alkali salts in country rocks from which these soils were formed. They made extensive examinations of the geological formations in Utah, Colorado, Arizona, Wyoming, Idaho, and Nevada, and analyzed the soil-forming country rock of these areas. These examinations and analyses revealed the fact that in these sections wherever alkali is present in very large JURASSIC BEDS 23 quantities it apparently originated from materials de- posited from concentrated solutions in some ancient sea. The deposits in the areas studied were made during Cre- taceous and Tertiary times which seemed to have been influenced by arid climatic conditions. This area in- cluding the eastern part of Utah, the western half of Colorado, and the southwestern part of Wyoming was covered with water during upper Cretaceous times leaving the Uintah anticline as an island. A description of the method of formation of these shales and sandstones that are so high in soluble salts is given as follows (17): ‘‘ Jurassic Beds. — The Jurassic beds contain highly colored red, yellow, gray, green, or blue shale and _ sand- stone ranging from fine grain to coarse grits. In the upper members of the deposit are often found thin lenses of limestone and an accumulation of gypsum. The ac- cumulation and position of the gypsum beds would seem to indicate that they had resulted from precipitation from the water of isolated brackish lakes. “At the end of Jurassic times the inland sea, in which the Jurassic deposit accumulated, disappeared and the area was subjected to erosion. This probably took place during lower Cretaceous times. Later the section was again covered with an inland sea and deposits were laid down unconformably on top of the Jurassic. “These belong to the Dakota beds, the lower part of which were composed of conglomerates and coarse sand- stones, above which are carbonaceous shales and some low- grade coal, overlain by more sandstone and highly colored shales. Above the shale are found thick beds of light- colored sandstone, shales, and dark-brown sandstones. “At about the end of the Dakota period there seems to 24 THE ORIGIN OF ALKALI have been some shifting and readjusting of the land as the Dakota beds are found to be quite thick in the northern section where the Mancos are thin; while in the southern section the Mancos are found to be exceedingly thick in places where the Dakota is comparatively thin. “Where they are not capped with the sandstone the beds do not form abrupt ledges, but weather off into rather rounded symmetrical clay hills— at least they appear - Fic. 1.— SALT-BEARING SHALE FORMATION. Tuts TYPE oF SOIL- FORMING MATERIAL IS A COMMON SOURCE OF ALKALI. to be clay hills. This disintegration of the shales gives rise to a very sticky, plastic clay which forms numerous cracks when dry, but becomes a continuous coat of plastic clay when wet. The material is so close grained that when rain falls upon it, it seals up all the pores and cracks so that water does not seem to penetrate it. These hills are very sparsely covered with vegetation and it is not an unusual thing to see an area of more than an acre which does not contain a single plant. “On these rounded clay hills one seldom has to dig more than a foot before the shale is found in place. However, the material covered is not uniform, especially on top of the clay knolls. The usual condition is that on the surface is from one to two inches of earthy clay, under which is MONTANA 25 from one to six inches of what appears to be a gray ashy material. On close examination this proves to be crystals of salt together with flocculent clay. Immediately under this is found the shale in place. Samples of the clay and gray ashy material, and the shale in place were taken separately, and the analyses show the nitrate contents of each. “The dark-colored shales show numerous crystals of gypsum in the cracks and bedding planes. Where the shale is dry and considerably weathered the gypsum appears like white flour. In the seams of the shale, but a foot or more under the surface in the same place, the crystals are still firm and solid. “At Emery, Utah, the gypsum crystals were not only taken out of the bedding plane of the thick layers, but numerous cross fractures were found which were also filled with gypsum crystals. Many of these cross fractures were as much as a half inch thick and pieces of gypsum this thickness and a foot long were removed from the shales. ‘* Montana.— Overlying the Mancos is the Montana Mesa Verde formations which are essentially sandstones, shales, and grits, light gray to dark brown in color. Car- bonaceous shales with thick beds of workable coal occur near their base, while sandstone occurs in the upper part. ‘Transition marked by increase of sandstone upward and . appearance of brackish and fresh water arise instead of marine conditions.’ “The upper layers of sandstone are often found in thick lenses and in many places contain high percentages of gypsum. The vegetation accumulated in these shallow seas resulted in the formation of coal. The sea seems to have increased sufficiently after the formation of the coal 26 THE ORIGIN OF ALKALI so the area was covered with thick layers of sand and shale, but the sea does not seem to have continued without interruption. Arid conditions seem to have again pre- vailed and the sea was reduced so that isolated portions became brackish and from these isolated waters gypsum and other salts were precipitated. “At the end of the Montana series the sea seems to have again entirely disappeared and the area was subject to erosion. “In the beginning of Tertiary times the section was Fic. 2.— MAncos SHALE HILL. Sor rrom THIS FORMATION Is HicH InN ALKALI. again covered with inland seas over much the same area as that occupied by the upper Cretaceous. The lower portion of these Tertiary deposits consisted of yellow and reddish-yellow sandy clays with regularly bedded sand- stones, with some conglomerates near the base, over which were deposited thin beds of light-colored sandstones asso- ciated over much of the area, especially in Utah, with rhyolitic ash beds and fresh-water deposits. In some places the ashes show distinct stratification as though they ARMS OF THE OCEAN 27 had fallen into the inland sea and had been worked over by the water. “The upper part of the Tertiary is composed of shaly sandstone and arenaceous shale, and in some sections thick beds of subbituminous coals. The shale and much of the sandstone are gypsiferous and in many places con- tain high percentages of sodium salts. “Near the close of the period the high evaporation seems to have so reduced the sea that parts of it became isolated lakes and from these brackish deposits were precipitated the salts and gypsum in question. “The Green River formation is composed essentially of light-colored thinly laminated beds, characterized by light-colored thin bedded shales. In appearance these shales of the Green River formation are much like those of the Mancos, especially some of the light-colored and thinner beds. “The Green River shales weather into a series of ‘bad lands, and it is not an unusual thing to have a large area entirely devoid of plants.”’ Arms of the Ocean. — Many soils have been formed by deltas of streams deposited in the ocean. These sometimes enclose portions of the ocean which may be shut off from the main body of water. The inclosed salt water gradually evaporates and leaves deposits of soluble salts or an alkali condition in the soil. This may be either a surface ac- cumulation that is comparatively easy to remove, or the salts may extend to considerable depth and be very difficult to handle. The type depends on the way in which the soil was laid down and the nature of the area of inclosed sea water. Subsequent deposits of soil may leave the alkali at considerable depths. The alkali land of the lower Nile Valley as well as the small alkali tract along 28 THE ORIGIN OF ALKALI the coast of Southern California derived their soluble salts from ocean water, which was inclosed in arms shut off from the main body of the ocean. Evaporation of Saline Lakes.— In arid countries nu- merous lakes without an outlet to the sea are found. All the water running into them is evaporated leaving the dissolved material to be gradually concentrated until the waters become saturated. Around the bodies of these lakes the soil is likely to be high in soluble salts. Arms of the lake may be shut off in the manner already described. These become centers of local salt accumulation. The lands for some distance surrounding these saline lakes are likely to be somewhat impregnated with alkali, but as the water iS approached the concentration is generally in- creased. There is usually a fringe near the lake that is entirely unproductive. This is surrounded by a zone in which only alkali-resistant plants grow, and still farther away the less-resistant plants are found. The Great Salt Lake in Utah is an example of this kind. Formation of Soluble Carbonates.—— On account of their soluble action on the organic matter of the soil and the hard crust which they form on the soil, the soluble car- bonates are, of all the soluble salts, most to be dreaded. Fortunately, they are not so widespread in their occurrence as are the chlorides and sulphates. ‘The comparatively insoluble carbonates of calcium and magnesium are very abundant but, being only slightly soluble, they are seldom. if ever harmful to plants. The exact method of soluble-carbonate formation is not well known. Cameron (3), from studies of greasewood and the creosote bush, held that these plants are instru- mental in converting the neutral salts into carbonates. Aladjem (1), from laboratory experiments with soil kept FORMATION OF SOLUBLE CARBONATES 29 in a water-logged condition and to which nitrates were added, concluded that sodium carbonate is readily formed from the nitrates in a water-logged soil. Treitz (22) concluded from his studies of alkali soils of Hungary that the soluble salts found in them are derived from the ash constituents of the plants produced on the soil and that the first and most necessary condition for the formation of sodium compounds, particularly the carbonates, is a calcareous subsoil, carbonates of the alkali being formed by the action of calcium carbonate on the humates, sulphates, and chlorides of the alkalies. From a study of water extracts of typical alkali soils and of soils to which various salts were added, Cedroits (5) concluded that sodium carbonate is not formed in the soil by direct reaction between sodium chloride and calcium carbonate, but that the sodium of the chloride replaces other bases — potassium, calcium, and magnesium — in humates and silicates, and the latter give up soda to the soil solution when the excess of soluble sodium salts is removed. Kelley (13) and Breazeale (2) have concluded that sodium nitrate reacts with calcium carbonate in the for- mation of small quantities of sodium carbonate. In dis- cussing this reaction Breazeale has the following to say: “In the reaction between sodium nitrate (or sodium chloride or sodium sulphate) and calcium carbonate, resulting in the formation of sodium carbonate, the presence of relatively small amounts of calcium nitrate or calcium chloride in the reaction impedes and may prevent the formation of sodium carbonate. The presence of a satu- rated solution of calcium sulphate in this reaction does not entirely stop the formation of sodium carbonate. Sodium nitrate, sodium chloride, and sodium sulphate in 30 THE ORIGIN OF ALKALI the presence of carbon dioxide react with calcium carbonate, with the formation of sodium bicarbonate. The presence of relatively small amounts of calcium nitrate or calcium chloride in this reaction impedes and finally prevents the formation of sodium bicarbonate. The presence of cal- cium sulphate has no effect in preventing the formation of sodium bicarbonate when sodium sulphate, or a mixture containing sodium sulphate, reacts with calcium carbonate. Sodium nitrate, sodium chloride, and sodium sulphate react with calcium carbonate in the soil with the formation of sodium carbonate (black alkali).”’ Nitrate Formation. — In alkali areas in many parts of several western states, certain brown-colored spots are found to contain large quantities of nitrates. Headden (10, 11) and Sackett and Isham (15) believe that these nitrates are formed within the soil by the action of non- symbiotic nitrogen-fixing bacteria. Stewart and Greaves and Stewart and Peterson (17, 16, 18) are convinced, however, that large quantities of nitrates seep into the soil with the other salts from the country rock and that local nitrogen fixation is a minor matter in the accumulation of sodium nitrate in alkali soils. Localization mentioned by Headden is claimed by him to preclude the theory of transportation and concentration in some cases. He states that certain of the spots are in the center of the valley the soil of which is so deep as to preclude the theory of transportation. He also says the ground water about and beneath the spots is not high in nitrates, which again apparently contradicts Stewart and Peterson’s theory. Concentration by Irrigation Water.— Whatever the original source of alkali in the soil, one fact has been well demonstrated. The condition may be greatly aggravated CONCENTRATION BY IRRIGATION WATER 31 by the improper use of irrigation water. The author (8) and many other workers have shown that the soluble salts are carried through the soil very readily by irrigation water. In some soils, like those in parts of the large in- terior valleys of California, the original salt content, though high, was not sufficiently high to prohibit the growth of crops. After irrigation the salts are leached from the higher land and carried to the lower, here to be concentrated at the surface until the amount becomes too great for ordinary crops to grow successfully. This con- dition is found to an extent in practically every large irrigated section of the world. Methods of preventing accumulation in this way will be more fully discussed in a later chapter. Considerable salt may also be added directly to the land by the use of irrigation water carrying large quantities of soluble salts. This method of contamination is dis- cussed rather fully in Chapter XV. Relation of Origin to Methods of Treatment. — An understanding of the origin of the alkali in a given area is essential to an intelligent treatment of the condition. This is as true in handling a soil as in treating a human disease. A physician who would give a remedy for a headache without seeking the cause of the trouble might entirely fail in curing. He might in any case give some simple treatment that would be harmless, but a really intelligent treatment would be founded on a knowledge of the cause of the trouble. Likewise in handling alkali land the source of the salt should be known. In one region an irrigation canal passed through a shale hill that was very high in soluble salts. Large quantities were dissolved and taken directly into the stream. Seepage was also excessive and much alkali was carried to the oe THE ORIGIN OF ALKALI lower land by the seepage water. The land was finally drained, but the alkali content of the soil was not reduced since the quantity added was greater than that lost by drainage. Lining the canal through the alkali-charged shale corrected the entire matter. Soil experts and drain- age engineers, before deciding on the methods of reclaim- ing any alkali tract, should discover all probable sources of the alkali in the area under consideration and select their methods of reclamation accordingly. REFERENCES t. ALADJEM, R. Decomposition of Nitrates as a Possible Cause of For- mation of Sodium Carbonates in Egyptian Soils. Cairo Sci. Jour. 6 (1912), No. 75, pp. 301-302. 2. BREAZEALE, J. F. Formation of Black Alkali (Sodium Carbonate) in Calcareous Soils. Jour. Agr. Res. 10 (Sept. 10, 1917), pp. 541- 590. CAMERON, F. K. Formation of Sodium Carbonate, or Black Alkali, by Plants. U.S. D. A. Rpt. No. 71 (1902), pp. 61—7o. 4. CAmERoN, F. K. The Soil Solution, pp. 110-125. (Easton, Pa. IQII.) 5. Ceprorts, K. K. Colloid Chemistry in the Study of Soils. Russ. Jour. Exp. Landw. 13 (1912), pp. 363-420. (Abs. E. S. R. 28, p. 516.) 6. CLARKE, F. W. The Data of Geochemistry. U. S. Geol. Survey, Bul. 616 (1916), pp. 22-35. 7. Dorsry, C. W. Alkali Soils of the United States. U.S. D. A. Bur. of Soils, Bul. 35 (1906), 196 pp. 8. Harris, F.S. The Movement of Soluble Salts with the Soil Moisture Utah Sta. Bul. 139 (1915), pp. I19g-124. g. HEAppEN, W. P. Alkalies in Colorado (including Nitrates). Colo. Sta. Bul. 239 (1918), 58 pp. 10. HEADDEN, W. P. The Fixation of Nitrogen in Some Colorado Soils. Colo. Sta. Bul. 186 (1913), pp. 3-47. 11. HEADDEN, W. P. The Fixation of Nitrogen. Colo. Sta. Buls. 155 (1910), 48 pp. and 178 (1011), pp. 3-06. 12. Hilgard, E. W. Soils, pp. 422-423. (New York, 1906.) 13. Krerttry, W. P. The Effects of Nitrate of Soda on Soils. Cal. Sta. Rpt. 1916, p. 59. Oo 14. 15. 16. 17. 18. IQ. 20. 2I. 22. 23. REFERENCES 33 Knicut, W. C., and Stosson, E. C. Alkali Lakes and Deposits. Wyo. Sta. Bul. 49 (1901), pp. 75-70. SAckETT, W. G., and IsHam, R. M. Origin of the “Niter Spots” in Certain Western Soils. Science, n. ser. 42 (1915), pp. 452-453. STEWART, R., and Preterson, W. Further Studies of the Nitric Nitrogen Content of the Country Rock. Utah Sta. Bul. 150 (1917), 20 pp. STEWART, R., and Peterson, W. The Nitric Nitrogen Content of the Country Rock. Utah Sta. Bul. 134 (1914), pp. 421-465. STEWART, R., and GreAveEs, J. E. The Movement of Nitric Nitro- gen in Soil and Its Relation to “Nitrogen Fixation.” Utah Sta. Bul. 114 (1911), pp. 181-1094. STEWART, R., and Peterson, W. Origin of Alkali. Jour. Agr. Res. Vol. 10 (Aug. 13, 1917), pp. 331-353. STEWART, R., and PeTerson, W. The Origin of “Niter Spots” in Certain Western Soils. Jour. Am. Soc. Agron. Vol. 6 (1915), pp. 241-248. TRAPHAGEN, F. W. The Alkali Soils of Montana. Mont. Sta. Bul. 18 (1898), pp. 22-23. TrapPHAGEN, F. W. The Alkali Soils of Montana. Mont. Sta. Bul. 54 (1904), Pp. 91-93. : Treitz, P. The Alkali Soils of the Great Hungarian Alféld Féldtani Kézlony, 38 (1908), pp. 106-131. (Abs. E. S. R. 20, p. 818.) Waltney, M., and Means, T. H. The Alkali Soils of the Yellowstone Valley. U.S. D. A. Bur. of Soils, Bul. 14 (1898), pp. 9-20. CHAPTERS EV. NATURE OF ALKALI INJURY TO THE PLANT Many of the general effects of excessive quantities of soluble salts in the soil are well known, but there still remain to be worked out a number of important problems, the solution of which will throw a great deal of light on the exact nature of alkali injury. Every farmer in alkali regions recognizes by the appearance of the soil and the limitations in crop growth the presence of alkali, but the actual underlying causes of the abnormal conditions are in part a mystery to even the most profound students of the subject. Prevention of Water Absorption. — Doubtless one of the very important injuries caused by alkali results from checked absorption of water by plants. It matters not how desirable other conditions are — how much plant- food is available, how deep the soil, or how favorable the temperature — if the plant cannot secure water it can make no growth. Roots absorb water from the soil by the process of osmosis. Because the cell-sap of root-hairs contains a stronger solution than the soil, water passes through the cell-wall and plasma membrane into the cell where it assists in the vital processes of the plant. Since carbohydrates are constantly being elaborated in the leaves, the cell-sap farthest from the roots is more con- centrated than that which has recently been diluted in the roots by the entrance of water from the soil. The transpi- 34 PREVENTION OF WATER ABSORPTION 35 Fic. 3.— Upper, NORMAL PLANT CELL. LOWER, CELL THAT HAS BEEN PLASMOLYZED. ration of water from the leaves also tends to concentrate the cell-sap in the leaves. This continuous diluting in the roots and concentration in the leaves causes a move- ment of water from root cells upward toward the leaf 36 NATURE OF ALKALI INJURY TO THE PLANT cells. This movement is necessary to the normal function- ing of plants. An ordinary plant, such as wheat, absorbs and transpires several times its own weight of water each day. Should this movement be reduced, the growth of the plant is retarded. If it is entirely shut off the plant dies, as pointed out by Pfeffer (12). The exact action that takes place when a plant cell comes in contact with a solution more concentrated than its own content was long ago pointed out by deVries (15) and Pfeffer (t1). Water passes out of the cell and the plasma membrane draws away from the cell-wall leaving the cell in a plasmolyzed condition. The rapidity of plasmolysis depends on the relative concentration of the solution inside and outside of the cell. So well known is this phenomenon that the method is used constantly in de- termining the concentration of the cell-sap under various conditions. The above conception helps to explain the observed action of plants. The soil solution of land high in alkali is stronger than the cell-sap; therefore, no plant growth takes place. In other land where there is less alkali, the concentration may be just strong enough to reduce the rate of water absorption but not enough to shut it off entirely. Under this condition the crop yield would be reduced. Thus, every gradation from a normal crop to no crop at all may be found in a single field. Under some conditions, such as after irrigation or heavy rains, alkali may be so diffused throughout the soil that the concentration at any point is not sufficient to prevent the crop from beginning a good growth. As the season ad- vances, the salt may accumulate at the surface of the soil until irrigation water is applied. It may then be washed down to the roots in a concentrated form causing EFFECTS ON GERMINATION 37 the death of the plant. The farmer says his crop has been burned since it has that appearance. As a matter of fact water may have been drawn out of the plant through the roots. This, taken with the loss by transpiration, des- sicates the pliant to the point at which it dies. Effects on Germination. — Before a seed can germinate it must absorb water. Ordinarily when a seed is planted in a moist soil it absorbs moisture and swells. At once Fic. 4. — AN ORCHARD PLANTED ON LAND THAT CAME FROM A FORMATION Hicu IN SOLUBLE SALTS. THE SALTS HAD KILLED Most OF THE TREES BY THE SECOND YEAR. the enzymes contained in the seed convert part of the starch into sugar which increases the strength of the solu- tion in the seed. This in turn hastens absorption and the seed soon contains sufficient moisture with which to carry on rapid cell division and growth. Within a few days a root is sent out, then a shoot for the top, and a new plant is growing. When a seed is placed in a strong salt solution or a soil that has a large amount of alkali, it does not absorb mois- ture; consequently, it lies dormant the same as it would in dry soil or in dry air. The coating on the seed protects it from absorbing most of the salts. It may not be injured, and as pointed out by Slosson (13) it will germinate when removed from the alkali soil to conditions favoring ger- 38 NATURE OF ALKALI INJURY TO THE PLANT mination. Under similar conditions, a plant would not only be hindered from growing, but would actually be killed. A salt solution not sufficiently strong to prevent entirely the germination of seeds may greatly delay it. The author has shown (3) that seeds which normally germinate in six days may be delayed as long as twenty-one days under conditions in every way similar except in the salt content of the soil. This delayed germination may be very serious in regions where the normal length of the growing season is greater than that required for maturity of the crop even if growth after germination were satisfactory. ‘ Effect on Structure of the Plant. — Vegetation growing on alkali soil has a characteristic appearance similar to that found growing under desert conditions. It generally lacks that bright green appearance of vigorous and healthy growth. This condition is observed even in water-logged land where there is an ample supply of moisture. A similar moisture supply without alkali would result in a succulent growth. Harter (4) examined the structure of plants to determine the effect of soluble salts in the soil. He found that culture in a soil containing considerable quantities of sodium chloride together with other salts produced measurable changes in the leaf structure of wheat, oats, and barley. The most notable modification produced was the conspicu- ous bloom or waxy deposit that formed on the surface of the leaves. This development of bloom was accompanied by an easily measured increase in the thickness of the cuticle and outer walls of the epidermal cells and by a marked decrease in their size. In regard to transpiration of the plants, it was found that when the alkali salts are present in sufficient con- INJURY AT THE SURFACE OF THE SOIL 39 centration to cause the modifications of structure noted, transpiration is much reduced. On the other hand, the same salts when present in amounts too small to produce any measurable influence upon structure have a decidedly stimulating effect upon transpiration. Fic. 5.— THe Lower Part OF AN ORCHARD BEING KILLED BY ALKALI BROUGHT TO THE SURFACE BY A RISING WATER TABLE. Similar modifications in structure have been pointed out by Kearney (7) who shows that thickness of leaves and stems with zerophytic tendencies characterizes plants growing in a saline soil. Injury at the Surface of the Soil. — Orchards and vine- yards in many cases have been planted in soils containing a rather high salt content, but not high enough to prevent growth. A root system may become thoroughly estab- lished in an untoxic lower layer of soil which is slightly 40 NATURE OF ALKALI INJURY TO THE PLANT alkaline and yet there may be a gradual accumulation of salt at the surface of the soil. This condition has the effect of corroding the plant and it often destroys the bark so thoroughly that the passage of elaborated food from leaves to roots is prevented. This injury is rather limited in the total damage done and may be overcome without great expense. Formerly it was thought that the principal injury to vegetation by alkali resulted from a corroding action. This is probably not the case, with the possible exception of the carbonates. The carbonates, in addition to any direct action on the plant itself, make the soil hard and a poor medium for the plant. REFERENCES 1. BREAZEALE, J. F. Effect of Sodium Salts in Water Cultures on the Absorption of Plant-food by Wheat Seedlings. Jour. Agr. Res. 7 (1916), pp. 407-416. 2. Duccar, B. M. Plant Physiology, pp. 64-83. (New York, 1911.) 3. Harris, F. S. Effect of Alkali Salts in Soils on the Germination and Growth of Crops. Jour. Agr. Res. 5 (1915), pp. 1-52. 4. Harter, L. L. Influence of a Mixture of Soluble Salts, principally Sodium Chloride, upon the Leaf Structure and Transpiration of Wheat, Oats, and Barley. U.S. D. A. Bur. Pl. Ind. Bul. 134 (1908), . 19 pp. 5. Hicxs,G.H. The Germination of Seeds as Affected by Certain Chemi- cal Fertilizers. U.S. D. A. Div. Botany, Bul. 24 (1900), 15 pp. 6. Hitcarp, E. W. Soils, pp. 326-428. (New York, 1906.) 7. Kearney, T. H., and Cameron, F. K. Some Mutual Relations be- tween Alkali, Soils, and Vegetation. U.S. D. A. Rpt. 71 (1902), 60 pp. 8. Jost, L. Plant Physiology, pp. 11-35. (Oxford, 1907.) g. Kearney, T. H. Plant Life in Saline Soils. Jour. Wash. Acad. of Sci. Vol. 8 (1918). 1o. Micnrers, H. The Mode of Action of Weak Solutions of Electro- lytes on Germination. Acad. Roy. Belg. Cl. Soc. (1912), No. 11, pp. 753-765. .(Abs. E. S. R. 29, p. 218.) REFERENCES 41 . PFEFFER, W. Osmotische Untersuchungen (1877), 236 pp. . Prerrer, W. Physiology of Plants, Vol. 1 (1900), pp. go-107; Vol. 2 (1903), Pp. 249-258. . Stosson, E. E. Alkali Studies. Wyo. Sta. Rpt. 1899, 29 pp. . True, R. H. The Physiological Action of Certain Plasmolyzing Agents. Bot. Gaz. Vol. 26 (1898), pp. 407-416. Vries, H. pe. Eine Methode zur Analyse der Turgorkraft. Jahr. f. wiss. Bot. 14 (1884), pp. 427-6or. CHAPTER V TOXIC LIMITS OF ALKALI NUMEROUS attempts have been made to determine the approximate quantity of the different alkali salts, both singly and in various combinations, which may be with- stood successfully by crops. Some experimenters have confined their work almost entirely to field observations. Others have workéd with natural alkali soils from the fields or soils made alkaline by the addition of salts in definite quantities and sown to crops under laboratory conditions. Still others have used different solutions containing salts as the medium for determining the toxicity of salts to plants. Each method has both advantages and disadvantages. The field work has often been done by sampling soils showing injury to plants and also adjoining soils where the effects of the alkali could not be detected. These observations are usually taken after the crop has made considerable growth, when the extent of injury may be estimated by the appearance of the plants. Such deter- minations may not take into consideration conditions pre- vailing during the earlier stages of growth. The vigor and delicacy of the plant at the time the alkali comes in contact with it appear to have much to do with its tolerance. Alfalfa, sugar-beets, and a number of other plants do not withstand alkali well in their seedling stages, but are among the most tolerant during later stages of growth. Most plants do better under alkali conditions as maturity 42 NUTRIENT SOLUTIONS 43 approaches. Since the conditions under which plants grow at different times is modified by rainfall, movement of ground water, evaporation, and other factors, am analvsis of the soils at a particular period of growth is not so definite for indicating toxicity as might be wished. Because of the difficulty in fixing definite toxic limits under field conditions, these observations will not be considered in the present discussion but will be reserved for Chapter XIV dealing with crops for alkali land. Toxicity in Solution. — Some of the first attempts to establish the toxic limits of alkali were made in solution cultures because the solution was easy to make up, easy to analyze subsequently where it was desired to learn the final concentration of the water, and because such com- plicating factors as absorption of the salts, moisture con- tent of the soil, and nature .of the soil were eliminated. Some of the experiments were carried on in cultural media, such as Knop’s solution, in an attempt to duplicate soil conditions as nearly as possible, whereas others were made in water containing only alkali salts. Nutrient Solutions.— Some of the nutrient-solution cultures were carried to later stages of growth than those with the toxic salts alone. Since, however, the strength of the nutrient solution, its composition, and other factors modify the results almost as much in some cases as the alkali salts the advantages of the culture media over the simple solutions are not so apparent. Plants are usually at their most critical life period in the secdling stages where they are still depending on the seed for their nu- trition. The results of LeClerc and Breazeale (17) show the tolerance of wheat seedlings for sodium chloride in culture solutions to be about 3000 parts per million, which is not essentially different from certain other results 44 TOXIC LIMITS OF ALKALI where the solution containing the alkali salts was tap water. Tottingham (29) did not find the introduction of potassium chloride or sodium chloride into Knop’s solution to have any marked effect on wheat plants, although the sodium chloride depressed the dry weight and length of roots of buckwheat. Alkali Solutions. — Alkali solutions have been used in a number of different ways to determine toxicity. Some experimenters have germinated the seed in the alkali solu- tions; others have used the alkali solutions in which to immerse the roots of the seedlings after they have germi- nated under normal conditions. Since conditions differ so widely under the two methods and because the time allowed for the alkali to become effective differs consider- ably, the two methods will be treated separately. Seed Germination. — Experiments with wheat in Wyoming (4, 27) show that salts hinder the absorption of water by the seed so that germination is retarded and that the kind of neutral salt is of less importance than the osmotic pressure of the solution. The work of Kearney and Cameron (14) on antagonism and of the author (10) apparently disprove the latter statement, however. From the Wyoming experiments which included salt solutions from 1000 to g0,cco parts per million in strength, it was found that inhibition was not retarded in as rapid pro- portion as the osmotic pressure of the solution was in- creased. Inhibition was apparently not influenced by the vitality of the seed nor did the salts affect the vitality of the seed when removed before sprouting. The weaker solutions up to 4ooo parts per million of sodium sulphate, sodium chloride, magnesium sulphate, or sodium car- bonate had a beneficial effect on the germination of the seed and the growth of the plants. SEED GERMINATION 45 Miss Magowan (19) states that alkali experiments are not reliable when they are continued only a week because the relative toxicity of the salts may change later. She found that although magnesium chloride was at first the most toxic of the chlorides, followed by sodium chloride, potassium chloride, and calcium chloride, this relation- ship did not hold throughout the experiment. Working with wheat seedlings in solutions of 0.01 normal, or 585 parts per million, sodium chloride, 850 parts per million sodium nitrate, 746 parts per million potassium chloride, and ro1r parts per million potassium nitrate, Micheels (21) found chlorine more harmful than nitrate ions, and sodium more harmful than potassium ions. He ascribed the variation to physiological and not chemical differences, as did also Slosson and Buffum (27) working with wheat, rye, and beans in the common alkali salt solutions. Sodium carbonate was the only salt found causing other than physiological injury. Wyoming experiments (27) show the highest concentra- tion of salts not retarding germination of wheat and rye to be as follows: MgSO, NazSO, NaCl NazCO3 Wheat. ..... 10,000 7000 4000 4000 IRE oi chante 10,000 7000 4000 1000 The vitality and time to germinate were effected dele- teriously as the strength increased above the minimum. Rye was as a general rule more tolerant of the higher concentrations of these salts than was wheat. Sigmund (26) found 5000 parts per million of sodium chloride or of sodium carbonate retarded the germination of cereal seeds in solutions of these salts. Vetch and rape seeds were killed in 5000 parts per million solutions 46 TOXIC “ELIMITS“OF ALKALI of sodium carbonate, but neither they nor wheat were injured in 5000 parts per million of sodium bicarbonate. According to this author the highest strength of sodium chloride endurable by the cereals was 5000 parts per mil- lion, by legumes 3000 parts per million, and by rape tooo parts per million. Jarius, as quoted by Kearney and Cameron (14), reports a stimulating effect on seeds of wheat, rye, rape, maize, beans, and vetch in a solution containing 4ooo parts per million of sodium chloride. Storp, as quoted from Kearney and Cameron (14), found this salt to stimulate germination in solutions as strong as too parts per million. In his work with solutions of sodium chloride in concentrations ranging from 1250 to 50,000 parts per million, Coupin (6) found the toxic limits for wheat to be 18,000 parts per million, of lupine 22,009 parts per million, of maize 14,000 parts per million, of peas 12,000 parts per million, and of vetch 11,000 parts per million. In this author’s experiment the endurance of the plant as a whole to the solution was taken to indicate the limit, whereas with some of the others the death of the root or some other part is sometimes taken to indicate the injury to the plant. He found the toxic limits for seashore plants to be several times that for the crop plants mentioned above. Nessler, who is quoted by Hicks (12), states that hemp seed was injured in germinating by 2500 parts per million of sodium chloride, clover by 5000 parts per mil- lion, and wheat by 10,000 parts per million. Rape seed was found to resist sodium chloride, potassium chloride, calcium nitrate, sodium nitrate, and potassium sulphate in concentrations as high as 5000 parts per million, but the vitality of wheat, rye, maize, beans, and peas was seriously injured when using solutions as strong as this (12). Sodium chloride had a stimulating effect. SEEDLINGS IN ALKALINE SOLUTIONS 47 Seedling Transference into Alkaline Solutions.-— This practice has been preferred to germinating and growing the plants in the alkaline solutions by some investigators. Certain experiments have indicated that plants may gradually become accustomed to salts as they grow older so that the injurious strength of solution at one period may not be so at another. By dipping the seedlings into the alkali solutions at a definite period after germinating, it has been hoped that a better standard for comparing toxicity would be fixed. Fer such work many standard conditions have been suggested but few of these standards have been accepted by other workers, so there is a wide difference in the conditions under which the toxicity of the plants have been determined. In the experiments of Kearney (13) and his co-workers the roots of the seedlings were placed in the alkali solu- tions for twenty-four hours and the death of the root tip was taken to indicate the toxic limit for the plant. As a result of this work, corn showed the toxic effect of mag- nesium less than other salts, but with lupines, alfalfa, wheat, sorghum, oats, cotton, and beets the magnesium compounds were considerably more toxic than other salts. The sodium chloride and sodium sulphate did not differ greatly in toxicity to the different plants in several cases, and the sodium carbonate was several times more toxic than these two salts in most cases. Corn, which is considered rather sensitive to alkali, endured more sodium carbonate than the other crops, whereas sorghum, cotton, and_ beets, which are usually resistant in soils, were affected most by this salt in solution. The limits for wheat were 650 parts per million of sodium carbonate, 2610 parts per million of sodium chloride, and 2830 parts per million of sodium sulphate. Comparing the two series with lupines 48 TOXIC LIMITS OF ALKALI it is seen that the variations are wide. In another experi- ment with lupine, where growth was prevented by the salts contained in the solutions, the magnesium salts were not so toxic as the carbonates of sodium, and the mag- nesium sulphate was the least toxic of all salts. This shows that very wide differences might be expected ac- cording to the method employed. True (30), using the above method for obtaining the toxic limit of lupine in sodium chloride solutions found it to be 3625 parts per million, which again shows the possible error. Coupin (5) allowed the plants to remain in the solutions until the whole plant showed the salts to be causing injury. His limits for lupine using sodium chloride, magnesium chloride, and magnesium sulphate were 12,000, 8000, and 10,000 parts per million for the respective solutions, which is about the same as the above results where growth was prevented. The resistance here is several times that found by Harter where the first injury was the point of indication rather than the death of the plant. Allowing the roots to remain in the salt solution twenty-one days and then weighing, the author (10) found wheat seedlings to produce about one-half as much as the check in the solutions containing 5000 parts per million of sodium carbonate, or in those containing over 10,000 parts per million of sodium chloride or sodium sulphate. Haselhoff (9) concluded that growth might be inhibited with a s5000-parts-per-million solution of sodium chloride and injury would result in the presence of 500 parts per million. Hansteen (8) states that 5000 parts per million of salts other than calcium are injurious when used singly, but when combined with lime the injury is greatly diminished. Others have found the same antagonistic effects of dif- IN SAND 49 ferent salts. This subject is reserved for Chapter VIII and will not be discussed here. A series of experiments was made by Marchal (20) to discover the effect of salts on the bacterial activities of the nodules of pea roots. He found alkaline nitrates in concentrations of too parts per million checked the tu- bercle production in water cultures. Ammonium salts were injurious in concentrations of 500 parts per million. Potassium salts at 5000 parts per million and sodium salts at 3333 parts per million tended to retard symbiosis, but calcium and magnesium salts favored it. Soil Results. — Soil studies of alkali have been found to show less variation for like treatment than solution studies. Some of the other disadvantages of solution studies of the effect of alkali on the higher plants are that the seed in germination tests and the root system are placed in an unnatural environment, the air circulation being eliminated and the normal resistance of the soil being changed. Studies of plants in solutions compared with similar soil cultures have shown that physiological dis- turbances are more likely to occur in solutions than in soils; the root-hairs are less numerous and the roots grow longer and thinner in the solution than in the soil. In- dividuals show much more variation due to unfavorable causes in the solutions than in the soils even where the soil consists of sand containing practically no nourishment. In Sand. — The physical conditions under which the plants grow seem to have some influence on their natural development. The author (10) found that whereas wheat seedlings produced about a half normal crop of dry matter in a sand containing tooo parts per million of sodium chloride in solution cultures, more than half a normal crop was obtained when the concentration was over 10,000 50 TOXIC: LIMITS OF ALKALI parts per million of this salt. For sodium carbonate the relationship between sand and solution cultures was about tooo and 5000 parts per million, respectively, and for sodium sulphate it was about 5000 to over 10,000 parts per million, respectively, for half-normal crops of dry matter. Le Clerc and Breazeale (17) found wheat seed- lings more tolerant for sodium chloride in sand than in solution. Breazeale (2) states that the reverse relation- ed Fic. 6. — EXPERIMENTS TO DETERMINE THE TOXICITY OF Various ALKALI SALTS. ship for nutrient solutions holds, 300 parts per million of nutrient solution being the best concentration for wheat seedlings, while 2500 parts per million was best for them in sand. Others have found the latter relationship to hold for sand. The size of pure quartz sand particles ap- parently had no effect on the toxicity of alkali in tests made by Harris and Pittman (11), but the quantity of moisture in the soil had considerable influence. The differences which may be expected in alkali experi- ments with differing moisture contents are shown in tests IN SAND 5i made by the author (10). The toxic limits of wheat for salts in a sand were as follows: sodium chloride with 12 per cent moisture 2900 parts per millon, with 18 per cent 5700 parts per million; sodium carbonate with 12 per cent 2700 parts per million, with 21 per cent 3300 parts per million; sodium sulphate with 12 per cent 8000 parts per million, with 24 per cent 16,000 parts per million. When the salts were added dry to the soil rather than in solution as in the above experiments, the limits of tolerance were higher, but the quantity of moisture added to the soils would influence the permissible quantity even more in such experiments than where the solutions were added be- cause the.quantity dissolved would be more dependent on the water present. In the work of Buffum and Slosson (4) sand was used as the medium for growing seed in a nutrient solution, an attempt being made to duplicate soil conditions as nearly as possible. Their work was with wheat and alfalfa in sand containing solutions with osmotic pressure equivalent to 2.03, 3.80, and 7.10 atmospheres which corresponds to 5000, 10,000, and 20,000 parts per million of sodium sul- phate, or 2700, 5100, and 9700 parts per million of sodium chloride. The conclusions were that the lower concentra- tions of the salts were stimulating to the plants buc that the higher ones were harmful. Solutions of sodium sul- phate, potassium sulphate, sodium chloride, and potassium chloride were all about equally harmful to those plants at the same osmotic pressures when based on germination and several other observations of the growing plants. A series of germination experiments in a sand by Stew- art (28) showed that 10,000 parts per million of sodium sulphate was generally fatal to seeds of barley, rye, wheat, oats, peas, alfalfa, and red and white clovers. The re- 52 TOXIC. LIMITS -OF ALKAUE sistance of the plants was about in the order given, barley being most tolerant. About 5000 parts per million of sodium carbonate or sodium chloride was fatal to the germination of these plants, and, excepting that peas were the most resistant to sodium carbonate and alfalfa was weakest for those salts, the order of toxicity was about as given above. Oats and mustard were found more resistant than flax for sodium chloride and sodium sulphate in pots of sand containing 315 to 1889 parts per million of these salts. Some influence of sodium sulphate was perceptible at the higher concentrations and the sodium chloride caused injury to the oats and mustard in the larger quantities. Wheat, oats, and peas failed to grow in soils containing 3go0 parts per million of chlorides buty survived in the presence of 10,000 parts per million of total salts. Wheat and oats could withstand 20,c00 parts per million of total salts where the chlorine content was less than 1250 parts per million. Claudel and Crochetelle (12) found that sodium nitrate in concentrations of 2000 parts per million prevented the germination of buckwheat and beans, injured or checked the germination of beet seed, and badly injured those of clover. However, it had very littie effect on wheat and bar- ley seed. Buckwheat was considerably, and clover slightly, affected by tooo parts per million. Barley was the only crop able to withstand 5000 parts per million of this salt. From the above discussion of the effects of alkali in sand on plants, it is seen that where allowance is made for the difference in the method of arriving at the toxic limits, the results are fairly uniform when compared with those of solution determinations. The two salts, sodium car- bonate and sodium chloride, are nearly the same in toxicity, IN LOAM SOIL 53 while sodium sulphate is considerably less harmful than the former two salts. In Loam Soil. — From a practical point of view loam soil is a much more desirable medium for studying the effect of alkali on plants than is either sand or a solution. Absorption, antagonism, and physical conditions must all eventually be taken into consideration before the real toxic effect of the salts under normal conditions can be arrived at correctly. The use of loam, or other soil containing organic matter and having high absorptive properties, complicates the determination of the toxicity of salts. Harris and Ditt- man (11) found that of two soils containing equal quantities of alkali and equivalent moisture contents, wheat on the soil with highest organic matter was injured less than where the organic matter was about as it is in ordinary loam. The organic matter appeared to remove sodium carbonate from the soil solution so that this salt appeared less toxic than has usually been ascribed to it from solu- tion or sand cultures or field extraction experiments. Wheat plants tolerated more alkali in a loam than in either a sand or clay and more in a coarse loam than a finer one with the same percentage of moisture, although with equivalent moisture contents the coarser loam was less tolerant than the finer. The toxicity of the salts de- creased with increasing percentages of soil moisture up to the maximum moisture content producing good crops. Changing the moisture relationship of the soil influenced the toxicity of sodium chloride and sodium sulphate more than did changing the organic matter, but the organic matter had the greater influence for sodium carbonate. High organic matter and moisture content offered the most favorable conditions for alkali toleration. 54 TOXIC. LIMES *OF ALKA The work of Haselhoff (9) on heavy loam and clay soils led him to conclude that because these soils absorb chlorine from the solutions of chlorides and thereby gradu- ally destroy the physical condition of the soil, the injurious infiuence of chloride solutions on soil productiveness and crop yield takes place gradually. Le Clerc and Breazeale (17) found the greater tolerance of wheat seedlings to sodium chloride in clay as compared a ana reer Fic. 7.— GrowTH or WHEAT WITH VARIOUS CONCENTRATIONS OF DIFFERENT SALTS. to sand and solution cultures to be due to the lime which the clay contained. Shutt (25) found that calcium oxide was very effective and calcium carbonate less so in correct- ing the toxicity of soil containing 50,000 parts per million of magnesium sulphate. Even when calcium oxide was used, germination was still retarded but a larger percent- age of the plants grew and the growth was more healthy. This antagonistic action of calcium and other salts will be taken up in greater detail in Chapter VIII. In the work done on the germination and growth of plants in Wyoming by Buffum (2), alkali soils were leached of their alkali and then made up to the required percent- IN LOAM SOIL SS age by the addition of the pure salts in one part of the experiment and in the other the soil was leached of a por- tion of its alkali sufficient to obtain the required alkali content. The alkali was two-thirds sodium sulphate and one-third magnesium sulphate and in concentrations from 10,000 to 50,000 parts per million. The test showed that in a soil containing 25 per cent moisture, rye germinated almost normally with 22,500 parts per million of these salts; barley nearly perfect with 10,000 but less than half normal with 22,500 parts per million in the natural alkali soil; wheat about two-thirds normal with 10,000 parts per million; alfalfa perfect with 10,000 parts per million but producing hardly a sprout in 22,500 parts per million; while turnips and oats produced less than one-half normal germination in soil containing 10,000 parts per million. The time taken for the seeds to germinate was increased in proportion to the salt present even for the lower quan- tities of alkali. Table IX summarizes the work of Guthrie and Helms (7) in a rich garden loam soil mixed with nearly an equal quantity of light sand. TABLE TX. CONCENTRATIONS OF SALTS AFFECTING THE GROWTH OF VARIOUS CROPS SopiuM CHLORIDE Sopium CARBONATE Wheat | Barley | Rye Wheat | Barley | Rye Germination affected. ....... 500 | 1000 | 1000 | 3000 | 2500 |} 2500 Germination prevented...... 2000 | 2500 | 4000 |} 5000 | 6000 | 5000 Growth affected............. 500 | 1000 | 1500 | 1000 | 1500 | 2500 Growth prevented ........... 2000 | 2000 | 2000 | 4000 | 4000 | 4000 From the figures it is seen that the resistance of seed to alkali during germination is not always the same as the 56 TOXIC LIMITS OF ALKALI resistance during later growth, and the relation between germination and subsequent growth differs for these two salts. With the following quantities of alkali added to loam soil the author (10) found the plants indicated in the table to produce about half-normal crops of dry matter. TaBLE X. QUANTITIES OF VARIOUS SALTS ADDED TO THE SOIL WHICH REDUCED THE YIELD OF Crops TO ABOUT Hatr NorMAL Crop Sodium Chloride Sodium Carbonate Sodium Sulphate Barleyseomecee ce 5000 10,000 Above 10,000 Oats. ce. Cae ee 4000 8,000 = = STOLOOO Wiheatss nue eer 3000 9,000 = | 10;000 Alfalltaee: (ary rons 3000 6,000 By ile} fo.o'o) Sugar-beets....... 3000 6,000 S| uRIOLOOO Cor ern 3009 4,000 «10,000 Bield peas: - 7-6. 3000 4,000 = g,000 It will be noted that the figures by the author are con- siderably above those of Guthrie and Helms, but that the carbonates when added to the soil in each case were less harmful than the sodium chloride. In the sand soil the sodium chloride and sodium carbonate were noted to be nearly equally toxic and for the field results presented in Chapter XIV the sodium carbonate shows nearly the reverse relationship to this. The low toxicity of the salts as compared with those for field determinations are probably due partly to absorption of some of the salts and to the even distribution and favorable moisture content possible in controlled experiments compared with field conditions. Of the salts used in the experiments of the author with wheat seedlings, the order of toxicity for salts added from highest to lowest was as follows: sodium chloride, calcium chloride, potassium chloride, sodium ni- trate, magnesium chloride, potassium nitrate, magnesium IN LOAM SOIL i | nitrate, sodium carbonate, potassium carbonate, sodium sulphate, potassium sulphate, and magnesium sulphate. This order does not hold when the concentration is determined by an analysis of the soil. The anions were found to affect the toxicity more than the cation, the chloride being the most toxic anion and sodium the most toxic cation. Bancroft (1), in his work with beans growing in. large pots to which alkali was added from below after the plants were growing until they wilted and died, found the fol- lowing quantities of salts just killed the plants: magnesium chloride, 2640 parts per million; sodium carbonate, 2710 parts per million; sodium nitrate, 3700 parts per million; sodium chloride, 5660 parts per million; magnesium sul- phate, 5820 parts per million; sodium sulphate, 6810 parts per million; and sodium bicarbonate, 12,300 parts per million. In germination tests on sugar-beet seed by Headden (Colo. Sta. Bul. 46) it was found that while 1000 parts per million of sodium carbonate permitted the seed to germinate freely, 5000 parts per million was injurious. The limit for sodium sulphate was about 8000 and for a mixture of the two about the same as the sodium carbonate. From the foregoing discussion of the various experi- ments with alkali under different conditions and from the results given in Chapter XIV on crops for alkali land, it is seen that the limits vary so widely because of the dif- ferent methods of arriving at these limits, that unless the conditions can be duplicated, considerable error might result from estimates secured by different experimenters. The estimates under field conditions would be expected to range through a wider limit because of the complicated changes within the soils and because of differences in de- 58 TOXIC LIMITS OF ALKALI termining the salts in the soils. With laboratory experi- ments, the same allowances must be made because of the various complicating factors such as moisture content, organic matter, antagonism of the salts, absorption, and differences in tolerance of the plants at different times. REFERENCES 1. BANcroFrt, R. L. The Alkali Soils of Iowa. Iowa Sta. Bul. 177 (1918) 2. BREAZEALE, J. F. Effect of the Concentration of the Nutrient Solu- tion upon Wheat Cultures. Science, n. ser. 22 (1905), pp. 146-149. 3. Burrum, B. C. Alkali. Wyo. Sta. Bul. 29 (1896), pp. 219-253. 4. Burrum, B. C. Alkali Studies, III. Wyo. Sta. Rpt. 1890, p. 4o. Also Rpt. for 1g00. 5. Couptn, H. On the Poisonous Properties otf Compounds of Sodium, Potassium, and Ammonium. Rev. Gen. Bot. 12 (1900), No. 137, pp. 177-193. (Abs. BE. S: R. 12, pp: 717—718:) 6. Couprn, H. On the Poisonous Properties of Sodium Chloride and Sea Waters toward Plants. Rev. Gen. Bot. ro (1898), No. 113, pp. 177- NOLS, US, By (VAMOS 1B WSs ING arte, Job BAL.) 7. GuTHrRiz, F. B., and Herms, R. Pot Experiments to Determine the Limits of Endurance of Different Farm Crops for Certain Injurious Substances. Agr. Gaz. N. S. Wales, 14 (1903), No. 2, pp. 114-120. See also 16 (1905). 8. HANSTEEN, B. The Relation of Plants to Salts in Soils. Nyt. Mag. Naturvidensk. 47 (1909), No. 2, pp. 181-192. (Abs. E. S. R. 23, p. 28.) 9. Hasetuorr, E. The Action of Chlorides on Soil and Plant. Fiihling’s Landw. Ztg., 64 (1915), Nos. 19-20, pp. 478-508. (Abs. E. S. R. 35, PP. 423-424.) to. Harris, F. S. Effect of Alkali Salts in Soils on the Germination and Growth of Crops. Jour. Agr. Res. Vol. 5 (1915), pp. 1-52. ii. Harris, F. S., and Pirrman, D. W._ Soil Factors Affecting the Toxic- ity of Alkali. Jour. Agr. Res. Vol. 15 (1918), pp. 287-310. 12. Hicxs, G. H. The Germination of Seeds as Affected by Certain Chemical Fertilizers. U.S. D. A. Div. Bot. Bul. 24 (1900), p. 15. 13. KEARNEY, T. H. The Wilting Coefficient for Plants in Alkali Soils. WSS IDG ANG Wie Tl ihavels (Cite, op), jos nZ—as- 14. KEARNEY, T. H., and Cameron, F. K. The Effect upon Seeding Plants of Certain Components of Alkali Soils. U.S. D. A. Rpt. 71. pp. 7-60. 16. 17. 18. IQ. 20. 21 22. 23. 20. 30. REFERENCES 59 . Kearney, T. H., and Harter, L. L. The Comparative Tolerance of Various Plants for the Salts in Alkali Soils. U.S. D. A. Bur. Pl. Ind. Bul. 113 (1907), p. 18. Kossovicu, P. Alkali Soils: Their Influence on Plants and the Methods of Examining Them. Zhur. Opuitn. Agron. (Jour. Exp. Landw.), 4 (1903), No. 1, pp. 1-42. (Abs. E. S. R. 15, p. 22.) Le Crerc, J. A., and BREAZEALE, J. F. The Effect of Lime upon the Alkali Tolerance of Wheat Seedlings. Orig. Commun., 8th Internat. Cong. Appl. ‘Chem. (Washington and New York), 26 (1912), Sect. VIa—XIb, app. p. 135.- (Abs. E. S. R. 20, p. 322.) Lesace, P. The Limits of Germination of Seeds after being Placed in Salt Solution. Compt. Rend. Acad. Sci. (Paris), 156 (1913), No. 7, pp. 559-562. (Abs. E. S. R. 29, p. 218.) MacGowan, FLorence N. The Toxic Effect of Certain Common Salts of the Soil on Plants. Bot. Gaz. 45 (1908), No. 1, pp. 45-40. Marcnat, E. Influence of Mineral Salts on the Production of Tuber- cle on Pea Roots. Compt. Rend. Acad. Sci. (Paris), 133 (1901), No. 24, pp. 1032-1033. (Abs. E. S. R. 13, p. 1017.) MicHeets, H. The Influence of Chlorides and Nitrates of Potassium and Sodium on Germinating Plants. Internat. Ztschr. Phys. Chem. Biol. 1 (1914), Nos. 5-6, pp. 412-410. Miyake, K. The Influence of Salts Common in Alkali Soils upon the Growth of the Rice Plant. Jour. Biol. Chem. 16 (1913), No. 2, Pp. 235-263. Miyake, Kk. The Influence of Acids, Alkalies, and Alkali Salts on the Growth of Rice Plants. Trans. Sopporo Nat. His. Soc. 5 (1913), No. 1, pp. 91-95; abs. in Bot. Cent. 126 (1914), No. 22, p. 588. (Abs. E.'S. R. 34, p- 31-) . Revert. Recherches de physiologie vegetale de l’action des poisons sur les plantes. (Paris, 1865.) Sautt, F. T. Alkaline Soils of Canada. Can. Exp. Farms Rpt. 1893, PP- 135-140. . StcmunD, W. Ueber die Einwirkung chemischer agentien auf die Kiemung. Landw. versuchst. 47 (1896), No. 2. Stosson, E. E., and Burrum, B. C. Alkali Studies, III. Wyo. Sta. Bul. 39 (1898), pp. 35-56. STEWART, J. Effect of Alkali on Seed Germination. Utah Sta. Rpt. 1898, pp. XXVi-Xxxv. TorrincHam, W.E. A Preliminary Study of the Influence of Chlorides on the Growth of Certain Agricultural Plants. Jour. Amer. Soc. Agr. 11 (1919), No. 1, pp. 1-32. Trur, R. H. The Toxic Action ot Acids and Their Sodium Salts on Lupines. Amer. Jour. Sci. 4 ser. 9 (1900), No. 51, pp. 183-192. (Abs. E.'S: Re 12, \p. roto.) CHAPTER VI NATIVE VEGETATION AS AN INDICATOR OF ALKALI Ir is highly desirable that the prospective landowner should, by studying the trees, shrubs, and grasses, be able to say that the soil is deep, well-drained, fertile, free from injurious properties, and capable of producing profitable crops. Upon many soils the native plants tend to group themselves to the exclusion of nearly all other species. Generally when such grouping occurs, there is some pecu- liarity of the soil which is made evident by such grouping. The luxuriant growth of one species of plant to the exclu- sion, or the near exclusion, of other species affords an excellent index to the nature of the soil. How Plants Indicate the Soil. — Certain plants in arid regions are seldom found except when the soil contains alkali salts. Davy investigating in California (1) states that ‘‘ there are at least 197 species natives of California, which are restricted to alkali soils.” Some of these plants seem to thrive only when some particular salt is present in certain strengths, resenting even small quantities of other salts. Other plants do well in the presence of any of the alkali salts so long as moisture or soil conditions are right. In each portion of the arid region may be found some plants which indicate extremely large quantities of salts when found alone. They indicate that so much alkali . is present in the soil that the land is worthless for agri- 60 HOW PLANTS INDICATE THE SOIL 61 cultural plants without reclamation methods first being applied. These characteristic plants are generally recognized by the farmers of the district in which they occur, but the exact qualities of the soil and the possibilities of its reclamation are not so often known. The kind of plant also varies considerably even within relatively short distances be- ——EEEEEEEEEEEE a on — eo Fic. 8. — ALKALI CRUSTS AT THE SURFACE PREVENTING THE GROWTH OF PRACTICALLY ALL VEGETATION. cause of difference in soil or drainage. Changes in climate or altitude also influence the type of plant that indicates a particular type of soil. A number of studies of the characteristic plants of alkali lands have been made together with the kind and amounts of alkali present in soils on which they grew. From these studies fairly intelligent conclusions may be drawn as to the kind and quantity of alkali in the soil without making a chemical analysis. In using native vegetation to indicate the alkalinity of a soil, however, it is essential that judgment should not be 62 NATIVE VEGETATION AS AN INDICATOR passed when only a few scattered or stunted plants are found. Generally when such scattered alkali-indicating individuals are found the soil contains some alkali, but the quantity is not clearly indicated. It is only when the plants produce a vigorous growth and occupy the land to the exclusion of non-resistant — if not all other species of plants — that they may be taken to indicate the kind and quantity of alkali characteristic of their species. | Saath e+ citi reece Ss ash 2 Fic. 9. — ALKALI LAND WHICH Is INDICATED BY THE GROWTH OF SHADSCALE. It should be kept in mind also that under certain condi- tions alkali-indicating plants may grow well where alkali may not be present in quantities injurious to general crops and that non-resistant plants may be growing well on land so strongly impregnated with alkali that farming would be practically impossible without reclamation. Such conditions as a shallow hardpan, a dry sandy layer of soil, or other conditions which cause the plants to suffer for want of water, as they do when in the presence of ex- cessive quantities of alkali, may allow the presence of the alkali-resistant plants in abundance to the exclusion of ALKALI-INDICATING PLANTS 63 others. On the other hand, shallow-rooted plants which cannot endure alkali may grow luxuriantly on land which contains alkali below the depth to which its roots feed but so near to the surface that when farming is attempted the land may soon be ruined. The latter condition is represented by the Bear River Valley, Utah, where sage brush, rabbit brush, and salt grass are growing on land practically free from alkali in the upper foot or so, but the soil to a depth of six feet contains from 6000 to 30,000 parts per million of salts, mostly sodium chloride. This salt is quickly concentrated near the surface when irrigation is practiced, making farming impossible. Alkali-indicating Plants.— Some of the characteristic plants of the western part of the United States which should, when present as a luxuriant growth upon the land, be regarded as indicating distinctly alkali soil, or soil which should be looked upon with suspicion until chemical analyses of it have been made, are given below. | Well-defined alkali-indicating plants Inkweed, or saltwort (Swaeda spp.) Tussock grass, or purple top (Sporobolus airoides). Torr. Bushy samphire, or Kern greasewood (Allenrolfea occidentalis) (S. Wats.). O. Ktze. Dwarf samphire (Salicornia spp.) Greasewood (Sarcobatus vermiculatus) Alkali-neath (Frankenia grandifolia campenstris). A. Gray Spike weed (Hemizonia pungens) Little rabbit brush (bushy goldenrod) (Jsocoma veneta) H. R. K. (A. Gray) Arrow or irrigation weed (Pluchea servicea) (Nutt.). Coville. (Sometimes Piuchea borealis) Salt-bush or shadscale (Atriplex confertifolia. etc.) Kochia or white sage (Kochia vestita) Salt-grass (Distichlis spicata). Greene Cressa (Cressa cretica truxillensis). Choisy Rabbit brush (rayless or false goldenrod) (Chrysothamnus spp.) 64 NATIVE VEGETATION AS AN INDICATOR Alkali-indicating plants not commonly forming the major portion of alkali-land vegetation Inhabiting moist saline lands: Arrow grass (Triglochin maritima and T. palustris) L. (Across continent) Alkali meadow grass (Puccinellia airoides. Nutt.) (Entire west. N.Mex.- Mont.) Marsh grass (Spartina gracilis. Trin.) (Oregon to Texas) Trailing buttercup (Halerpestes cymbalavia. Pursh.) (Rocky Mts., n. seacoast) Shooting star or American cowslip (Dodecatheon salinum. Nels.) (Western Wyoming, Utah, Idaho) Glaux (Glaux maritima. 1.) (Subsaline soil west of Mississippi) Aster (Aster angustus. T. and G.) (Colorado and Utah to Minnesota) Aster (Aster pauciflorus. Nutt.) (New Mexico, Arizona, Utah) Crepis (Crepis glauca. T.andG.) (West of Missouri to Nevada) Plowman’s wort (Pluchea camphorata) (Coast of Florida to Texas) Mousetail (Myosurus apetalus. Gay) (Western North America) Valeria (Valeriana furfurescens. Nels.) (Colorado and Wyoming) Pyrrocoma uniflora. Greene. (Montana to Colorado and Utah) Rush (Scirpus nevadensis. Wats.) (Wyoming, California) Tuber bubrush (Scirpus paludosus) Inhabiting soil not moist at the surface: Bud-brush (Artemisia spinescens. Fat.) (Colorado to Montana and west) Aster (Aster zylorhiza. Nutt.) (Southcentral Wyoming. Naked, clayey, saline) Pyrrocoma lanceolata. Greene (Saskatchewan. Northern Colorado and west to Nevada) Flaveria angustifolia. Pers. (Eastern Colorado and New Mexico to western Texas) Pepper grass (Lepidium montanum. Nutt.) (Montana to New Mexico and westward) Wild barley (Hordewm nodosum. UL.) (Arizona to Alaska) Wild rye (Elymus salinus. Jones) (Wyoming and Utah. Saline situations) Goosefoot or pigweed (Chenopodium rubrum. L.) (Across continent north- ward) Goosefoot or pigweed (Chenopodium soccosum. Nels.) (Southern Wyoming) Monolepsis spp. (Colorado and westward. Saline soils) Botanically, probably half of the alkali-loving plants belong to the Chenopodiaceae, or goosefoot family, which DISCUSSION OF PLANTS 65 includes beets, mangles, samphire, saltwort, salt-bush, and greasewood. Some of the smaller families such as Frankeniaceae, Plumbaginaceae, Rhizophoraceae, and Tama- ricaceae are noted for the alkali resistance of most of the species. Some other families, notably Gramineae, Cru- ciferae, and Compositac, contribute some of the more important plants found to do well on alkali lands. Discussion of Plants. — ‘‘/nkweed, or saltwort, is a perennial shrub with a small, fleshy, stem-like leaf. Each winter the plant dies down close to the ground leaving behind a dark-colored bush” (5). It is found on some of the worst alkali lands of California (1), in one in- stance being found on soil containing 38,000 parts per million of total salt in the top foot of soil, and it has been found growing luxuriantly with as high as 32,000 parts per million of total salts in the top foot of soil. Where growing luxuriantly, the soil has been found to contain 837 parts per million of sodium carbonate, and 3313 parts per million of sodium sulphate in the upper three feet of soil. It thus indicated a soil with a high content of black alkali. Where found in abundance the soil is generally. of a heavy, sandy-loam or a clay-loam texture occurring on low-lying lands and reclaimable only at great expense. Because of the presence of black alkali the soil is puddled so badly that rainwater generally evapo- rates from it before it will penetrate. When found on the higher lands, the soil is generally underlain with a hard- pan near the surface. Tussock grass (Sporobolus airoides) sometimes forms a coarse, matty or tree-like growth, the trunks of which are often from 18 to 20 inches high. It forms feathery purple panicles in late summer and is relished by stock better than most any other native alkali-resistant plant. Ani- 66 NATIVE VEGETATION AS AN INDICATOR mals eat only the grass part of the plant leaving the trunk- like stems behind. It is a good alkali indicator for the arid Southwest, but is not common north of the goth parallel, or about the center of Utah and Nevada. It has been found growing in a soil with an alkali content of 31,190 parts per million in the upper four feet, although it makes its best growth with about 3000 parts per million Fic. 10.— GREASEWOOD AND SHADSCALE. ‘THESE PLANTS INDICATE ALKALI IN THE SOIL. of total salts. Of the separate salts in soil on which the plants were growing vigorously, the following amounts were found: Sodtimlcanrbondtese terme eee 1437 parts per million Sodium_chlon dearer eee ee ene: 387 parts per million Sodiumysulphatesee errr sere e eens 1227 parts per million It has been found growing with over 10,000 parts per million of sodium chloride and 20,000 parts per million of sodium sulphate. The range of tolerance is great; hence, scattered individuals should not be taken to indicate ex- cessive quantities of alkali, although when thick and DISCUSSION OF PLANTS 67 vigorous, especially when occurring along with other alkali indicators, it may be safe to call the land unsuitable for farming. It may occur on dry prairie soils where very small quantities of alkali are present. Kern greasewood or bushy samphire (Allenrolfea occi- dentalis) is a shrubby evergreen bush 1 to 4 feet in height with numerous cylindrical, fleshy, practically leafless alternating branches, and with a large taproot. It is nearly always found on the low-lying, and generally clayey, soils with a plentiful supply of moisture. Soils on which it does well are usually saturated with water throughout the growing season, but may become “dry bogs” during part of the year. The salt content of such soils is almost invariably high, sometimes reaching over 30,000 (1, 2) parts per million of total salts with a good growth of the plant. It has been found to make a good growth in the presence of 300 parts per million of sodium carbonate, 13,000 parts per million of sodium chloride, and 17,090 parts per million of sodium sulphate. It grows with a higher sodium chloride content than any other plant known at present. Soils on which this plant forms the major growth are usually hopelessly alkaline; even salt bushes fail on the soils on which Allenrolfea does best. The heavy soils make reclamation by drainage difficult so that such soils can seldom be used profitably. Dwarf samphire (Salicornia subterminalis and other species) is a nearly leafless plant with cylindrical, fleshy, many-jointed, opposite branches. All soils upon which it has been found are excessively alkaline. It grows well on land with a total salt content of 27,000 (1, 2) parts per million in the upper four feet. Analyses of the soil on which it was growing well showed it to contain 757 parts per million of sodium carbonate, 7852 parts per mil- 68 NATIVE VEGETATION AS AN INDICATOR lion of sodium chloride, and 19,627 parts per million of sodium sulphate. Thus, it resists larger quantities of sodium chloride and sodium sulphate than most other plants. Both the seashore and the inland species indicate land which is useless for farming until reclaimed by pro- longed draining, which in many cases is at present un- economical. Greasewood (Sarcobatus vermiculatus) is one of the most common alkali-indicating plants found on moist saline Fic. 11.— THE BorDER BETWEEN GREASEWOOD AND SALT GRASS. THE LAND INCREASES IN ALKALI TOWARD THE SALT GRASS. flats of the intermountain country. Viewed at a distance - the patches of greasewood have a pleasant bright-green color decidedly in contrast to much of the darker or gray- ish alkali vegetation. Besides the numerous sharp spines which protect the small fleshy leaves from browsing ani- mals, the plant is bitter and salty so that no useful animal will eat it. Although it has not been found on soil con- taining more than Sooo (4) parts per million of total salts in the upper feet, its large taproot has been found pene- trating soil with nearly double this amount of salt (mostly DISCUSSION OF PLANTS 69 sodium chloride). Hilgard (2) reports 1170 parts per million of sodium carbonate, 230 parts per million of sodium chloride, and 2260 parts per million of sodium sulphate as being characteristic quantities of the common alkali salts present where the plant does best and that its presence “invariably indicates a heavy impregnation of land with black alkali or carbonate of soda”’ (2, page 542). Although the latter statement is generally true, it has been found on land showing only sulphates, and Kearney and others (4) found it growing on land in Utah without sodium carbonate as a characteristic salt. Kearney says it is not an infallible alkali indicator as it was found making its largest and thriftiest growth on dunes of pure sand. It is usually associated with a rich silty or sandy soil, moist in the upper foot and containing excessive quantities of salts. It will endure larger quantities of alkali than most alkali plants. Greasewood soils are sometimes too alkaline to permit profitable reclamation. Alkali-heath (Frankenia grandifolia campenstris) is a perennial herb with opposite or clustered simple leaves and with a deep-rooted, flexible, wiry, rootstock. It is a hardy plant which often persists as a weed on cultivated land. Although it generally indicates strong alkali where it is growing luxuriantly, it will grow with a great varia- tion in alkali content — from about 200 to 31,000 (1, 2) parts per million of total salts. The optimum quantities found by Hilgard (2) ranged from about 4000 to 17,600 parts per million in the upper four feet of soil. Of this amount 43 to 1224 parts per million was sodium carbonate, 360 to 636 parts per million sodium chloride, and 2158 to 17,220 parts per million sodium sulphate. Hilgard re- gards land that grows this plant to be unfit for crops with- out reclamation, although Mackie (5) says it will generally 70 NATIVE VEGETATION AS AN INDICATOR contain comparatively small quantities of alkali, and “‘where this bush is found growing uniformly over an area to the exclusion of the most resistant alkali indicators, the alkali is found below the surface from 1 to 3 feet ina free sand or sandy loam soil. This “land yields crops ” of alfalfa and grain or orchards and can be kept free from injurious quantities of alkali by proper methods of irriga- tion and drainage.” Cressa (Cressa cretica truxillensis) is a perennial herb with a woody base from which many leafy branches ex- tend. The leaves are almost sessile and are characterized by their silky, villous, and hairy nature. Cressa is a com- mon sea-coast plant in many of the arid parts of the world. In the United States it is found along the Texas coast and scattered throughout California, extending at least to the Arizona line. Alkali-heath has been found growing with a higher total salt content than Cressa, but Cressa is a surer indicator of irreclaimable alkali land because the lower limit in which it grows is much higher. Although sulphates predominate in Cressa soil, it will be noticed that it does well with chlorides in quantities dangerous to ordinary crops. Salt-bush, or Shadscale (Atriplex spp.), is of two types — the perennial, which is generally bushy or shrubby, and the type that occurs as an annual weed. ‘The leaves are usually alternate, simple, and often silvery, scurfy, or having an ashen-gray color, the bush type often being mistaken for sagebrush. The bush belongs to the same family as the beet and it can readily be detected by its beet-like seeds. A number of the Afriplex species grow in soil which contains little or no alkali, but the moisture conditions are generally unfavorable on any soil which has a vigorous growth of them, and most of the common DISCUSSION OF PLANTS 71 species of the western arid country produce their most luxuriant growth in the presence of dangerous quantities of alkali. Land upon which saltbush — either bush or weed — grows best is generally light and free from alkali in the top foot or so, but is underlain by heavier soil which is likely to contain large quantities of alkali. Such soils are seldom underlain by hardpan and are usually porous so that they may be reclaimed by flooding. Crops can as a rule be grown on the soil on which saltbush occurs, but there is likely to be a rise of alkali where great care is not taken to prevent it. The alkali is likely to be of the white type entirely, although it will grow with as much as 1200 parts per million (2) sodium carbonate in the soil. The annual Aiériplexes are similar to the bushes in color and appearance of the leaves but do not have the persistent wocdy base of the latter. They range in height from about 1 to 4 feet. Land upon which Atriplex forms the principal vegetation should be looked upon with suspicion 72 NATIVE VEGETATION AS AN INDICATOR until borings and analyses show it to be free from alkali, unless plans are laid for immediate drainage. Soils con- taining as much as 10,090 parts per million (3) of salts — mostly sodium chloride — but with the upper foot or so dry and free from alkali, have been found to produce excellent saltbushes. They grow equally well in the presence of nearly 8000 parts per million (2) of sodium sulphate. Because of the porous, dry, upper soil, and the tendency to have alkali beneath, such soils are ordinarily unfit for dry-farming. Kochia, or White Sage ( Kochia bestita), is a low-lying shrub with its branches close to the ground and with a strong taproot which, however, seldom penetrates to a greater depth than one foot. New shoots are sent up from its roots. Its leaves are alternate, sessile, villous, narrow, and entire. The branches as well as the leaves are fre- quently covered with short woolly hairs. It is found in the intermountain country from Colorado to Nevada. Land upon which it occurs is usually free from injurious salts in the upper foot or so, some observations showing the upper foot to contain about 1200 parts per million of total salts (4), but the soil beneath which its roots feed is almost invariably impregnated with so much alkali that deeper rooting plants, such as the sagebrush (Ariemesia tridentata) cannot exist. Kochia itself is not alkali resistant, but where it exists to the exclusion of sagebrush and similar nonresistant plants the lower depths of soil are either high in alkali or underlain at shallow depths with a hardpan which prevents deep penetration of roots. Either con- dition makes the land undesirable for general farming be- cause of the likelihood of a rise of alkali. Kochia land frequently contains some black alkali and the soil is often rather impervious so that reclamation is difficult. OTHER PLANTS Fle Salt-grass (Distichlis spicata) occurs throughout the world, being the most common plant found on alkali lands. It grows well on land so free from alkali that some of the common alkali-loving plants such as greasewood fail, but can withstand and make a good growth with as much as 24,000 parts per million of total salts in the soil. No preference is shown for any of the alkali salts. The high- est quantities found in soil on which it grew well are as follows: SOdUumMe CarpOUdteaaece scien eriacme ee 8517 parts per million SOC MINE CHIGHIG Gaur is nics es eer 4398 parts per million Sodiumysulphatere... 10s oss 2750 parts per million These quantities are only suggestive, however, as great variations are found wherever the grass is found. It is a poor indicator of alkali either quantitatively or quali- tatively, but when taken together with other plants grow- ing with it something of the nature of the land may be indicated. Other Plants. — A number of other plants which do well on alkali soils, but which are not so distinctive as a general rule, are the following: Rabbit brush or false golden-rod (Chrysothamnus spp.) which is cluster-flowered and woody-based; Plowman’s wort (Pluchea camphorata (1) DC.), a spicy or salt march Fleabane found in the marshes of Texas and Mexico as well as on the eastern and southern coast of the United States; little rabbit brush (Jsocoma veneta Grey) a perennial composite bush about 18 inches high with a sparse, smooth, dark-green foliage usually growing in deep loamy soils with a medium salt content; spike weed (Hemizonia pungens), a yellow- flowered spiny composite which grows in a dense mass to the exclusion of most other plants on comparatively weak alkali land with fair drainage; arrow or irrigation 74. NATIVE VEGETATION AS AN INDICATOR weed (Pleuchea borealis), a composite with a brush-like head supported on a stem 4 to 8 feet high which tolerates a limited quantity of alkali on a porous, deep, well-drained soil. Plants other than those discussed above are char- acteristic of alkali lands in their respective districts, but sufficient data are not at hand to determine their exact reliability as to alkali resistance. Many other plants fa ~~ . 73 4.66 Rago ae k,055 8,630 6,075 Welhysbe oe p25 IL.65 IZ.98 | 4,138 13,912 0,774 ISUPUSEs Ot |i pe sen 14.62 14.58 | 5,192 30,544 25,352 September] “=.=. - 16.20 NOM ellegs 5d. 41,353 35,599 Wctopersa|" asst 2.42 2.42 8590 21.625 20,166 November] . 2... 3.88 Bate) ||vagsetrs) 3,159 1,781 December ly si... Bets) .28 99 1,099 1,000 1904 | maine Sl) | goaae I.50 1.49 533 473 60 yeeray: eer 2.06 2.06 732 11,891 II,159 Vilar chiveies| mame ee Tee ay) 458 13,049 12,591 race al (hee 1.76 rte 7A0) 625 9,558 8,933 Miaivg SS | sete, 2.64 2.63 938 1,537 599 June..... 31 4.26 AeSsuleiss he 787 — 726 etsy Beene 60 II.09 11.66 | 3,930 0,634 5,005 August... Be M302 |e a fe oo) 17,776 13,084 September 14 5.52 5-65 | 1,960 14,480 12,520 ————— ee ES qlotales |) aanon 110.72 123.69 |45,572 265,889 | 223,586 164 RECLAIMING ALKALI LANDS out 3648 tons of salt over the measuring weir in addition to the salt washed to lower depths by percolating water. Tables XVII and XVIII show in detail the rate of re- moval of the salts. TasLe XVIII. QUANTITIES OF ALKALI AT DIFFERENT DEPTHS oF SOIL ON CERTAIN DATES AND COMPOSITION OF DRAINAGE Water. SWAN TRACT NEAR SALT LAKE City SEPTEMBER, 1902 May, 1903 OcTOBER, 1903 | OCTOBER, 1904 goo Alkali | Part of | Alkali | Part of | Alkali | Part of | Alkali | Part of in 4 ft. in 4 ft. in 4 ft. in 4 ft. Soil Total Soil Total Soil Total Soil Total (p.p-m.)|(per cent) |(p.p.m. |(per cent)| (p.p.m.)| (per cent) |(p.p.m.)| (per cent) First Foot... ./17,038] 20 6,238} 14 1,263 8 475 4 Second Foot..|19,250| 23 8,125] 19 2,288] 15 1,600] 13 hinds oOotees||22:0715|ne 27 S825 eae 4,125| 28 2,050) 24 Fourth Foot..|24,775| 30 |15,813] 63 7,008] 49 6,250] 57 Aho talleaeee 835038! tea NASsSOLN Ew TS2G4)) yee 10,975 Average....|20,785] .. WOR /GI) ae Boon ee 2,744 Chemical Analysis of Drainage Water (in Parts per 1,000,000) Seepage Water rom Tile Drainage Drainage Drainage Drainage Constituent Drain before Water, Water, Water, Water, Trrigating, June 18, 1903}April 4, 1904]May 10, 1905|June 26, 1906 Oct. 9, 1902 Canna cee 45 72 61 BH 37 Mice a ee 96 257 162 70 89 INdeereee 6,966 Ten pst 7,262 3,060 3,924 | RoR et hee 319 260 209 Tos 126 SOR pererree 3,870 8,886 3,531 2,143 2,288 Cle ee ee ay 7,650 12,070 8,881 3,958 4,312 HEQO mates ee 1,320 037 800 666 605 COR tke 71 55 40 50 60 Total Solids . 20,346 34,308 21,000 10,701 TL So DRAINAGE 105 Hart (6) gives an example of a tract on which before drainage the ground water stood within 2 feet of the surface. A white crust of salts covered the surface and nothing of value grew on the land, the only vegetation being an occasional salt weed. The average salt content for the first 4 feet of depth was 2.25 per cent. A drain- age system was installed and in a month so much of the excess water in the soil was removed, that the water- table was practically down to the level of the drains. The drainage water was very high in salt. By the end of the month an analysis showed the salt content of the soil to have been reduced to 1 per cent. The ground surface was cultivated and irrigated with a limited supply of water and crops were planted. These gave only fair results. Meanwhile the higher temperature of summer had in- creased evaporation and the average salt content for 4 feet was found to have increased to 1.28 per cent in spite of drainage. A near-by uncultivated and unirrigated spot which had been affected to some extent by the drainage system showed an average salt content for the first four feet of 1.51 per cent. It was evident that drainage alone would never reclaim the tract; hence, a heavy flooding was given which reduced the average salt content for the first 4 feet to 0.43 per cent, less than one-fifth of the origi- nal content. At the same time the near-by uncultivated spot showed an average salt content for the first 4 feet of 1.73 per cent, an increase which was caused by percolation from flooding the adjacent land. Thousands of examples could be given to show the effectiveness of drainage in reclaiming alkali lands. Many failures have also been recorded. These have resulted from improper methods which were decided on before all conditions were studied and also from the fact that the drainage system was expected to do everything. 166 RECLAIMING ALKALI LANDS It. I2. Te. 14. 15. 16. We 18. 9. REFERENCES . BREAZEALE, J. F. Formation of ‘Black Alkali” (Sodium Carbonate) in Calcareous Soils. Jour. Agr. Rsch. 10 (1977), pp. 541-590. . Brown, C. F., and Hart, R. A. The Reclamation of Seeped and Alkali Lands, Utah Sta. Bul. 111 (1910), pp. 75-92. . Dorsry, C. W. Alkali Soils of the United States. U.S. D. A. Bur. of Soils, Bul. 35 (1906), 179 pp. Harris, F. S. The Movement of Soluble Salts with Soil Moisture, Utah Sta. Bul. 139 (1915), pp. 119-124. Harris, F. S., and Rospinson, J. S. Factors Affecting the Evapora- tion of Moisture from the Soil. Jour. Agr. Rsch. 7 (1916), pp. 439- 461. Hart, R.A. The Drainage of Irrigated Farms. U.S. D. A. Farmers’ Bul. 805 (1917), 31 pp. HEADDEN, W. P. “Black Alkali’ in the San Luis Valley. Colo. Sta. Bul. 231 (1917), pp. 3-15. Hitcarp, E. W., and Loucuripcr, R. H. The Distribution of the Salts in Alkali Soils. Cal. Sta. Rpt. 1895, pp. 37-69. HitcarpD, E. W. Soils, pp. 455-484. (New York, 1906.) . Lipman, C. B. New Experiments on Alkali Soil Treatment, Univ. Cal. Pub. Agr. Sci. 1 (1915), pp. 275-290. Means, T. H. Reclamation of Alkali Lands in Egypt. U.S. D. A. Bur. of Soils, Bul. 21 (1903), 48 pp. Roret, A. Cultivation of Salt Lands. Jour. Agr. Prat. n. ser. 9 (1905), No. 22, pp. 710-712. (Abs. E. S. R. 17, p. 814.) SANDSTEN, E. P. Reclaiming Niter Soil in the Grand Valley. Colo. Sta. Bul. 235 (1917), 8 pp. Suinn, C. H. Alkali Reclamation at Tulare Substation. Cal. Sta. Rpt. 1899-1901, Pt. I, pp. 204-213. Sunn, C. H., and Hitcarp, E. W. Reclamation of Alkali Land with Gypsum at the Tulare Station. Cal. Sta. Rpt. 1893-94, pp. 145- 140. Symmonps, R. S. Experiments with Nitric Acid in Alkaline Soils. Agr. Gaz. N. S. Wales, 21 (1910), No. 3, pp. 257-266. Symmonps, R. S. Note on Action of Nitric.Acid in Neutralizing Alkaline Soil. Jour. and Proc. Roy. Soc. N. S. Wales, 41 (1907), pp. 46-48. Trinstey, J. D. Drainage and Flooding for the Removal of Alkali. N. Mex. Sta. Bul. 43 (1902), 29 pp. Weir, W. W. A Preliminary Report of the Kearney Vineyard Ex- perimental Drain. Cal. Sta. Bul. 273 (1916), pp. 103-123. CHAPTER XIII PRACTICAL DRAINAGE DurING the early years of irrigation in America no provision was made to remove the excess water that always collects in the lowlands of irrigated districts. This is one of the chief reasons for the accumulation of alkali. The modern up-to-date irrigation system should include some method of drainage whereby any excess of water is carried out of the land; for there are always a few farmers who, to the detriment of themselves and their neighbors, use too much water. A drainage system laid out at the same time as the irrigation system will in some cases be more simple than one installed after the land becomes a bog. In swampy places drain ditches are constructed with difficulty and tile cannot be laid evenly and securely. Unfortunately, the reclamation of most alkali land is not undertaken until after the condition has become bad. This means that many difficulties are encountered. Of course it would not be wise to install drainage when the irrigation system is put in unless there is likelihood of water-logging. The problem is doubly complex since not only must the excess soil water be removed but the alkali must also be washed out. Advantages of Drainage. — Where drainage systems are installed on land there is generally a complete transforma- tion; many conditions favoring crop growth are improved. Most important in an alkali soil is the removal of the excessive salt. In many soils where the salt content is 167 168 PRACTICAL DRAINAGE not high enough entirely to prevent crop growth, there is sufficient to reduce the yield to a point that is unprofit- able. The expenses are practically the same in raising | half a crop as a full one. In the one case farming is carried on at a loss, and in the other a good profit may be realized. Thus, removing alkali by drainage may make highly pro- ductive millions of acres of land that is only moderately = —- Eee a Fic. 20.— Frrtp READY FOR LAYING TILE. successful. There are also millions of acres at present wholly unproductive that may be made to yield bounte- ously by removing the alkali. Drainage removes the excessive water from the soil. By lowering the water-table the plant is given a larger root zone from which to draw both food and water. If only the surface foot or two can be drawn on for food the plant cannot be expected to be so well supplied with nourish- ment as it would with a feeding area of five or six feet. * ADVANTAGES OF DRAINAGE 169 Strange as it may seem, drainage increases the water supply of the plant and reduces the injury that is likely to be caused by drought. Roots do not readily penetrate into the ground water. They are confined to the zone above the water-table from which they absorb capillary water. Free water is unavailable to them.