smn The Wural Text-Book Series Lyon anp Fipprin, PrincipLes or Sort Man- AGEMENT. G. F. Warren, Evements or AGRICULTURE. A. R. Mann, BEGINNINGS IN AGRICULTURE. J. F. Duccar, Soutnern Fierp Crops. B. M. Ducear, Pianr PHYSIOLOGY, WITH SPECIAL REFERENCE TO PLANT PRODUCTION. G. F. Warren, Farm MANAGEMENT. M. W. Harper, ANIMAL HUSBANDRY FOR ScHoots. E. G. Monreomery, THE Corn Crops. H. J. WHEELER, MANURES AND FERTILIZERS. ‘sy[nser poos Ayjenbo oa1s 0} punoj useq savy oyeydsoyd prow pure ‘ysejod Jo o}etmMur ‘epOS JO dU81}IN ‘“Sosseis yURUTUOp et} aurB0eq yUEq puUv]syT opoyy puv doyper puv ‘pomoes oq you pynod AyyouTTy Jo pueys poos B SULUUT] JNOYITAA “A UL2) fo pr oy) ym Yseyod jo a}¥1mMu pue ‘oyeydsoyd prow “epos jo o}eaA}Ta ‘ysejod jo ova} YIM poonpoid dodo oy], ‘STIVOINGHD GNV AWIT HLIM GaZITILYGd AHLOWLY, — “T “SITY MANURES AND FERTILIZERS A TEXT-BOOK FOR COLLEGE STUDENTS AND A | WORK OF REFERENCE FOR ALL INTERESTED IN THE SCIENTIFIC ASPECTS OF MODERN FARMING iEpys oO” HOMER J. WHEELER, Pu.D., D.Sc. i AGRICULTURAL CHEMICAL EXPERT OF THE AMERICAN AGRICULTURAL CHEMICAL COMPANY AND FORMERLY PROFESSOR OF AGRIOULTURAL CHEMISTRY AND DIRECTOR OF THE AGRICULTURAL EXPERIMENT STATION OF THE RHODE ISLAND STATE COLLEGE New Work THE MACMILLAN COMPANY 1914 All rights reserved Coryrignt, 1913, By THE MACMILLAN COMPANY. Set up and electrotyped. Published August, 1913. Reprinted August, 1914. 7 a gph POSS. Ly () M (Fer oa ee L => 4 — 3/< -) VE c =— — eS Nortoood Press J. 8. Cushing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. ee ne, i 7 Ow Ge PREFACE THE preparation of this volume was undertaken for the purpose of meeting a distinct lack in collegiate agricultural textbooks in the United States. It was hoped to prepare a book reasonably free from extended details, such as are found in certain of the larger:foreign works, and likewise to avoid the rather superficial treatment of the subjects which has necessarily characterized many of the books which have been written for the purpose of meeting the earlier requirements of the American agricultural colleges, and the present demands of agricultural high schools. The intent has been to provide in a measure for the needs of the graduate student in agriculture; also for the requirements of students in the agricultural colleges, teachers in agricul- tural schools, graduates of agricultural schools and colleges, agricultural institute lecturers, and the rapidly increasing number of intelligent men who are daily interesting them- selves in the scientific phases of modern farming. In connection with the treatment of some of the newer and more controversial phases of certain of the topics, au- thorities have been cited freely, in order that the reader may readily pursue the subjects further, if desired. These cita- tions have been introduced at the bottom of the respective pages, so as to permit of more convenient and ready ref- erence than would be possible if they were placed at the ends of chapters, or at the end of the volume. Certain points have been referred to repeatedly in dif- Vi vi PREFACE ferent connections, in order that the reader may not have his train of thought interrupted by frequent enforced refer- ence to preceding pages or chapters. The subject of guano and of human excrement will per- haps be thought to have been treated too fully from the historical standpoint, yet the agricultural teacher is ex- pected to be conversant with such matters, and he can best familiarize himself with them when they are being con- sidered in their manurial relations. Unusual attention has been paid to the sea-weeds of the Atlantic coast for the reason that they are largely used directly as fertilizers by the farmers, whereas those of the Pacific coast, on account of their larger size, are now being more generally utilized in a commercial way. The consid- eration of sea-weeds is important, for notwithstanding that they interest directly only a relatively small section of the country, detailed information concerning them is not readily accessible to those students who need it. In the discussion of the dung of domestic animals, much attention is given to the bacteria and other organisms in- volved in its decomposition, for the reason that they greatly affect its value under the varying conditions of moisture and aération. Not only have organic nitrogenous manures been carefully considered, but also the precautions necessary in determin- ing their relative availability, and the results of such deter- minations by different investigators. The subject of nitrates and of ammonium salts has been quite fully treated, especially from the standpoint of their cumulative and indirect effects. The new synthetic nitrog- enous fertilizers, calcium cyanamid and calcium nitrate, have also received attention. More than the customary amount of space has been devoted to the subject of lime and its use, and magnesia, soda, and PREFACE Vil manganese have been discussed more fully than in most of the previous works of its kind. Brief reference is made to the so-called catalytic fertilizers, and to the effect of carbon disulfid, tricresol, toluene, and other substances, certain of which are held to destroy soil amebe and ciliates, and hence to promote unusual bacterial development and ammonification. Care has been taken to discuss the reasons for many of the conflicting opinions on various subjects, in the belief that those entering upon agricultural research work should be taught to give such matters more careful consideration than is frequently the case. No apology is offered by the writer for the frequent refer- ence to certain lines of research work at the Rhode Island agricultural experiment station, for the reason that he can speak of these results in a more authoritative way than of work done elsewhere. Furthermore, the work has been, in some respects, of a pioneer character, and has not been duplicated. . In certain of the chapters matter will be found which is of too theoretical a character to meet the needs of the casual reader, and he is requested to pass it over charitably, remem- bering that the prime object of this work is not to give rule- of-thumb directions, but rather to aid in inculeating such general principles as shall aid in making the student as independent as possible of them, and at the same time fur- nish a foundation upon which to base his future study of the various relations of fertilizers and manures to soils and crops. _ As a matter of convenience to the vast majority of read. ers, and because of the confusion incident to the use of the names of the elements in place of phosphoric acid, potash, soda, lime, and magnesia which are in common use through- out the civilized world, the old and well-established nomen- Vili PREFACE clature has been retained, instead of following the lead of one or two American writers who have seen fit to depart from the universal custom. Acknowledgments are due to the agricultural experiment station of the Rhode Island State College for all of the illustrations which have been used;* likewise to Brooks, Cameron, Dehérain, Fritsch, Griffiths, Hall, Halligan, Hei- den, Hilgard, Johnson, King, Murray, Lohnis, A. Mayer, Mintz and Girard, Storer, Van Slyke, Voorhees, Vivian, and others, whose works have been freely consulted; also to Mr. Wilcox, of Mystic, Conn., for details concerning the han- dling of menhaden, to L. H. Bailey and P. B. Hadley for helpful suggestions, and to my son, Carl O. J. Wheeler, for aid in reading the proofs. A debt of acknowledgment is also recognized to Goessmann, Henneberg, Von Koenen, V. Meyer, Th. Pfeiffer, Tollens, and Stockbridge, whose work and teachings have been of fundamental assistance to the author, as well as a source of lasting inspiration. H. J. WHEELER. May 12, 1913. CONTENTS CHAPTER I PAGES HistoricaL IntTRopuCcTION 3 - : F : ; : 1-9 Chemistry throws new light on the subject of manuring — The views of Liebig—The early work of Lawes and Gilbert — Assimilation of atmospheric nitrogen by plants — Other facts established by Lawes and Gilbert — The utilization of nitrates and guano — Employment of ammo- nium salts — The manufacture and use of superphosphates —The German potash salts — The manufacture of basic slag meal — New processes for combining atmospheric nitro- gen — New catalytic and other fertilizers. CHAPTER II Nicest Sorin ; F is . ; : P p P 7 10-18 Conservation of night soil now less necessary — Amount of urine produced per person — Chemical composition of human urine — The amount of solid excrement per indi- vidual — Former methods of disposal in Europe were bad — Orientals conserve human excrement carefully — The conservation of human excrement in Paris — Poudrette from human excrement— Treatment of excrement with burned lime — The ‘‘ A. B, C.’’ and ather methods of con- servation — The novel method of Sindermann— Repeated use encourages undue leaf growth. CHAPTER III Tue Dune or Farm ANIMALS AND ITS PRESERVATION . . 19-34 Influence of feed and age of animal on dung — Influence of litter on manure — Collecting and caring for dung — Horse manure —Cow manure — Sheep manure — Hog ix x CONTENTS PAGES manure — Hen and pigeon manure -—— Amounts of litter used as absorbents— Comparative absorbent power of litters for water and ammonia— The degree of conserva- tion effected by litters — Losses of manure lessened by packing and trampling — Soil a powerful absorbent of am- monia— Miintz and Girard’s results on the absorption of ammonia—The action of gypsum as a preservative of -manures — Reasons for using gypsum in excess — Gypsum safe to use — Gypsum -compared with other chemical pre- servatives — Preservation by antiseptics. CHAPTER IV THe ORGANISMS AND FERMENTATION OF DUNG : ; . 85-54 The number of microérganisms present in cow and horse manure — Significance of microdrganisms in ma- nure — Microérganisms in litter — Urine, when voided, essentially free from microdrganisms — The numbers of bacteria decrease gradually——The disadvantage of antiseptics— Types of microérganisms present in ma- nure — Aérobic forms — Spore-forming anaérobic forms — Actinomycetes —The yeasts— The molds and other organisms— Animal organisms destroy bacteria — The effect of heating and of antiseptics on manure — Destruc- tive changes in the non-nitrogenous matter of dung — Losses not confined to the cellulose — Most of the aérobic and anaérobic organisms in dung are active — Diastatic action — Decomposition of starch — Decomposition of pec- tin — Decomposition of cellulose — Decomposition of fats and waxes— Decomposition of urea— Decomposition of hippuric acid — Changes produced in uric acid — Ammon- ification of solid manure and litter — Terms used in dis- cussing the decomposition of dung — The nature and cause of the losses occurring in manure — Losses less by fer- mentation when moist and compact — Losses increased by bacteria from intestinal tract — Losses smaller in the later stages of decomposition — Fresh manure lacks immediate effectiveness— The great necessity of moisture in heaps of solid manure — The preservation of the liquid manure. CONTENTS j xl CHAPTER V PAGES Tue PracticaAL UTILIZATION OF MANURES . : . . 65-64 Storage versus direct application of manures — Immedi- ate incorporation of manure with the soil — Losses occur- ring in heaps in the field and if broadcasted — The time to spread manure on fields — Certain vegetable substances aid denitrification in manures — Losses by denitrification less serious if used moderately — Other factors affecting losses by denitrification — The lasting effect of stable manure — Manure profitably supplemented by chemical fertilizers — Factors governing the use of manure and chemicals — The use of coarse manures— Reason for even spreading of manure — Manure favors the disintegration of old sod. CHAPTER VI SEA-WEEDS 5 ; : ; : ‘ : 2 : . 65-74 The value of sea-weed known to the ancients — Chemical composition of sea-weeds — The composition varies at dif- ferent seasons of the year — Sea-weed of chief importance in New England — The value of eel-grass— Value limited by distance of land — Practical utilization — Effect on the quality of certain crops — Sea-weed quick in its action — Sea-weed compared with farm-yard manures — Not a well- balanced manure — Sea-weed as affecting the need of lime — Freedom from weed seeds a great advantage —Com- posting sea-weeds — Size and rapidity of growth of sea- weeds. CHAPTER VII GuUANOS . : : : : ; - ; : : . 15-85 Experimental trials of guano — Commercial introduction into Europe — The general nature of guano — Chemical composition of guanos— Chemical composition affected by climatic conditions — Color and physical character — Chincha Island guano — Significance of oxalic acid and oxalates in guano — Influence on the physical character of soils — The distribution and sources of guano — Adultera- tion of guano — Rectified or dissolved guano — The man- xi CONTENTS PAGES ner of using guano— A _ poorly.balanced manure — Bat guano unlike Peruvian and other guanos — Appearance of bat guano — Where found — Chemical composition — Distribution — Precautions in the use and purchase of bat guano — Bat guano needs supplementing. CHAPTER VIII Fiso, Cras, Lopster, AND SIMILAR WASTES . : ‘ 86-93 Fish long used as a fertilizer — Early catching of fish for fertilizer purposes — Special process for preparing fish for fertilizer — Fish waste in Japan — In Newfound- land — Norwegian wastes from cod and whales— Meth- ods of handling menhaden in the United States — Fish waste treated with sulphuric acid — Chemical composi- tion and utilization of whale products — Availability and use of fish guano — Requires supplementing — Fish scrap may be employed without further treatment — Value of fish waste depends on the climate and soil — Shrimps — The king-crab —The common crab— Lobster refuse — Star-fish. CHAPTER IX Common SLAUGHTER-HOUSE NITROGENOUS WASTE Propucts 94-102 Dried meat meal— All readily utilized by fertilizer manufacturers — Chemical composition of meat meal— Availability of meat meal — The nature of bone tankage — Composition of bone tankage — Value of bone tank- age as a fertilizer — Method of employment — Chemical composition of red dried blood — Chemical composition of black dried blood — Reason for occasional low nitro- gen content of blood—Chemical composition of the better commercial blood — Crystallized blood — Certain processes of preparing dried blood — Dried blood, if very fine, is highly hygroscopic — Availability of blood de- pendent upon soil conditions — Processes of preparing horn meal and hoof meal— Chemical composition of CONTENTS Xili PAGES . horn meal — Chemical composition of horn and hoof meal —The nitrogen content of hoof meal— Efficiency of hoof meal — Adulteration of horn and hoof meals — Pre- paratory treatment of waste leather — The chemical composition of prepared leather waste — The availability of nitrogen in leather — Treatment of leather with car- bonates of the alkalies— Leather really not so valuable as it appears. CHAPTER X OTHER MIscELLANEOUS NITROGENOUS SUBSTANCES. 5 lsh Feathers— Hair bristles and wool— Tannery hair — Waste silk — Wastes from hares and rabbits — Chemical composition of waste wool— Wool waste as a manure — Effect of superheated steam on wool waste — Concern- ing Petermann’s tests of availability — Soluble wool waste not subject to loss by leaching — Benefit from steaming not equally applicable to all other nitrogenous wastes — The value of garbage tankage low— Character of shoddy and felt refuse —Chemical composition of shoddy and felt — Use of felt and shoddy wastes as manures — Character of soot—Chemical composition of soot — Soot benefits physically — Soot rarely toxic — Light soot best — Insects and cocoons — Peat and muck — Peat and muck especially valuable on light soils —Salt and fresh muds — Cereal and other seed by-products —Composition of cotton-seed meal — Composition of linseed meal — Composition of malt sprouts — Composition of castor pomace — Composition of wet brewer’s grains — Compo- sition of gluten feeds — Utilization of the spent wash of distilleries— The process of Vasseux—The process of Effront. CHAPTER XI THE AVAILABILITY OF ORGANIC NITROGEN AND Factors AFFECTING IT . ; : : = ; . 113-124 The factors of temperature and moisture — Effects on the soil reaction — Effects of large applications at the outset — Employment of different amounts of nitrogen X1V CONTENTS — Other elements must be supplied generously — False conclusions a result of neglect of conditions — Results by Eckenbrecher — Results by Kellner—Results by Petermann — Precautions suggested by Wagner and Dorsch — Results of tests by Wagner and Dorsch — Re- sults by Wheeler and Hartwell — Results by Voorhees — Results by Kellner on wet soil — Results by Seyffert — Results by Heinrich — Results by Johnson — Results by the nitrification method of Miintz and Girard — The pepsin method — The permanganate method — Lipman’s - ammonification method. CHAPTER XII * CaLcium AND Potassium NITRATES . z : > : Calcium nitrate a new fertilizer — Production possible due to cheap electricity — The work of Lovejoy and Bradley — The process of Birkeland and Eyde — First product too hygroscopic — Processes for lessening hy- groscopic tendency — Chemical composition — Calcium nitrate as a fertilizer — Danger of the earlier products injuring horses and workmen — Extent of the output of calcium nitrate— Cost of producing calcium nitrate — Other processes — Sources of potassium nitrate — Artificial niter beds — Made for industrial purposes from nitrate of soda— Potassium nitrate often economical for agricultural use— Chlorin avoided by using potassium nitrate. CHAPTER XIII NITRATE OF SODA Sources of nitrate of soda— Concerning the origin of the Chilian nitrate of soda— The first exploitation of nitrate of soda— Chemical composition and purification of nitrate of soda— Impurities of nitrate of soda — Physical characteristics of nitrate of soda— The availa- bility of nitrate of soda as plant food— Quantities to apply and care in using — Nitrate of soda corrects soil PAGES 125-131 132-146 CONTENTS XV PAGES acidity — Physical effects of the residue from nitrate of soda — The residual soda may liberate potash — Re- sidual soda may replace potash in part — The soda of nitrate of soda may in certain cases conserve the soil potash — Soil improvement by using nitrate of soda — Nitrate of soda may injure certain soils — Residual bene- fit not due solely to hygroscopic effects — Soda as a car- rier of phosphoric acid into plants— Nitrate of soda conserves the lime supply of the soil— Nitrate of soda not a stimulant — Yields quick returns on the manurial investment — Possible effects on the microdrganisms of the soil— Ammonium nitrate — The synthetic produc- tion of ammonia and ammonium salts. CHAPTER XIV AMMONIUM SALTS AND CALCIUM CYANAMID : 5 . 147-164 The manufacture of ammonium .sulfate — Thiocya- nates a former toxic impurity of ammonium sulfate — Chemical composition of sulfate of ammonia — Sulfate of ammonia must not be mixed with alkaline substances — — Absorption of sulfate of ammonia by soils —Its use exhausts soils of lime — Nitrogen of sulfate of ammonia fixed by microdrganisms — Its efficiency as a fertilizer — Soda important in trials of nitrate of soda and sulfate of ammonia — Double decompositions follow the use of am- monium salts-—— Partial soil sterility sometimes caused by sulfate of ammonia — Conditions caused in acid soils by sulfate of ammonia not fatal to all plants— Aids in rendering certain grasses dominant — May cause the suspension of certain bacterial activity — Sulfate of am- monia liberates plant food — Ammonium salts fleeting in their effects — Leach less quickly than nitrates — May cause injury on light calcareous soils — Ammonia may injure plants—Calcium cyanamid a new product — Manufacture of calcium cyanamid —Changes in ca!- cium cyanamid resulting in the soil — Utilization for the manufacture of urea and other substances — As a ferti- Xvi CONTENTS PAGES lizer —Practical difficulties connected with calcium cy- anamid — The output of calcium cyanamid. CHAPTER XV NaTURAL PHOSPHATIC FERTILIZERS . * < . 165-190 Bone as a fertilizer — Chemical composition of bone Composition of the ash— Composition of weathered bones—Treatment of bone for the removal of fat— Effect of steaming on the nitrogen content — Bone wastes from industries — Fermentation and other methods of disintegrating bone— Bone meal as a fertilizer— The soluble and reverted phosphoric acid of bone — Bone tankage— Fish as a source of phosphoric acid — The nature of floats— Soils on which to use floats — The ac- tion of manure on floats — How floats should be used — Liming in connection with the use of floats — Apatite or phosphorite — Chemical composition and occurrence of apatite — Wagnerite — Coprolites — Phosphatic guanos — Nassau or Lahn phosphate — French, Belgian, and Portuguese phosphates — The phosphates of Russia and Northern Africa—The phosphates of South Caro- lina — Florida phosphates — Tennessee phosphates — Phosphates of the Western States— Occurrence and composition of certain aluminum phosphates — Roasting increases the efficiency of aluminum phosphates — The solubility of artificial aluminum phosphates — Iron phos- phates formed in soils— Solubility of artificial ferric phosphate. CHAPTER XVI MANUFACTURED PHOSPHATES AND STUDIES OF SOLUBILITY 191-227 The manufacture of basic slag meal—Influence of silica on the efficiency of basic slag— Range in composi- tion of low and high grade basic slag — German methods of determining availability— The degree of fineness — Chemical composition of basic slag — The constitution of basic slag — Practical use of basic slag meal — Care in mixing basic slag with certain other materials — Arti- CONTENTS Xvil PAGES ficial basic slag meal— Wiborgh phosphate — Wolter’s phosphate — Palmaer phosphate — Other artificial phos- phates — The preparation of superphosphates — Treat- ment of bone with small amounts of sulfuric acid — Free phosphoric acid in superphosphates — Strictly chemical use of the term ‘‘ phosphoric acid’? — The relationship of the various phosphates — Care in the manufacture of superphosphates — Practical process of making super- phosphates — Double superphosphates — Dissolved bone — Dissolved bone-black — Laboratory studies on the solubility of phosphates — The action of water on mono- calcium phosphate — The action of water on dicalcium phosphate — The action of water on tricalcium phosphate — Determination of ‘soluble’’ phosphoric acid — Ad- vantages of soluble phosphoric acid — The reversion of monocalcium phosphate — Liming after reversion with iron and: aluminum oxids — The determination of re- verted phosphoric acid — Reverted phosphoric acid not all from dicalecium phosphate — The term available phos- phoric acid — Insoluble phosphoric acid — The reversion of monocalcium phosphate— Reversion often beneficial in some respects — Reversion with iron and aluminum - oxids serious — Reversion as affected by pyrite —The fixation of superphosphates in soils rapid — Fixation of phosphates confined chiefly to the surface soil — A vaila- bility of fixed phosphates may still be high — Injury from applications of superphosphates rare — Soils on which superphosphates may give poor results — Superphos- phates have a flocculating action on soils— Various soil conditions affecting the choice of phosphates to be used — Crops and conditions for which superphosphates are especially adapted. CHAPTER XVII Porassic FERTILIZERS . : : : : : e . 228-246 Wood ashes and lime-kiln ashes— Cotton-seed hull ashes — Saltpeter waste — Other wastes containing pot- ash — Potash from sea-weeds and other plants — Anal- XViii CONTENTS ° PAGES yses of sea-weeds — Tobacco stems — Indian corn cobs — Potassium nitrate — Potassium carbonate — History of the German potash deposits — Americans buy a German potash mine — The famous potash contracts — Mode of occurrence and distribution of potash deposits in Europe — Chemical composition of the more important potash salts — Duration of the deposition of potassium salts — Natural deposits of potassium salts elsewhere — Kainit —Sylvanit and carnallit— Muriate of potash — High- grade sulfate of potash — Double sulfate of potash and magnesia, or double manure salt — Double carbonate of potash and magnesia — Silicate of potash — Potassium carbonate (pearl ash) — Greensand — Phonolite, nephe- line, alunite, leucite, and feldspars as sources of potash. CHAPTER XVIII Tue THEORY AND PRACTICE OF POTASH FERTILIZATION . 246-260 The alleged ill effects of the chlorin of potassium and other salts — Reasons for the diversity of ideas concern- ing chlorids— Use of chlorids increases the need of liming — The fate of sulfate of potash in the soil — Con- cerning the retention of potash by soils — Teachings of the Rothamsted investigations — Various factors affect- ing absorption — Potassium essential to plant growth — Potassium aids carbohydrate formation — Other func- tions of potassium — Potassium increases the size of the individual grains of cereals— Effect of potassium on photosynthesis — Potassium in connection with turgor — Functions of potassium not necessarily shown by re- sults which its absence produces — Potassium as a neu- tralizer and carrier within the plant— Potassium may contribute to the ‘‘luxury consumption’’ of plants— Certain functions and effects of potassium salts in soils — Effect of potassium salts on legumes— Effect of a lack of potassium on grasses and other plants — Potas- sium salts act best in wet seasons— Lack of potassium more serious for some crops than for others — Potash conservation in the soil by sodium salts. CONTENTS xix CHAPTER XIX PAGES LIME AND 1TS RELATION TO SOILS AND FERTILIZERS . . 261-294 The occurrence of lime—Distribution and effect of limestone — Kinds of lime used in agriculture —The effect of lime on nitrogen availability — The effect of lime on denitrification — The effect of lime on soil texture — The use of lime in connection with phos- phates— Lime as a destroyer of worms and slugs — Need of liming suggested by soil acidity — Liming the most economic basic treatment — Chemical methods for determining the lime requirements of soils — Effect of lime on vegetable decay — Effect of lime on nitrogen content of humus — Rational rotation and the turning under of sward should accompany liming — Avoidance of liming to conserve humus, not wise — Carbonate of lime versus slaked or burned lime — The penetration of lime into soils — Expulsion of ammonia from soils as a result of liming — Influence of lime on nitrification — Effect of calcium and magnesium carbonates on ammon- ification — General ideas as to the indirect manurial action of lime— Results with sodium and magnesium salts illustrate how lime acts indirectly — Fixation of potash after liberation by lime— Caustic lime attacks powdered quartz — Losses of lime by leaching —Coarsely ground limestone compared with fine limestone and marl —Concerning the practical use of lime — Pure lime com- pared with magnesian lime. CHAPTER XX LIMING IN ITS RELATION TO PLANTS . 2 é ; . 295-3808 Plants may transform lime compounds — Miscellane- ous effects of lime on plant diseases— Lime in connec- tion with potato scab — Lime may be used and potato scab avoided — Lime may cause injury to pineapples — Effect of lime on the size of potatoes— Liming may hasten crop maturity — Soils needing liming for some plants ideally adapted to others — Details concerning the lime requirements of different plants. xx CONTENTS CHAPTER XXI PAGES Gypsum AND WastEe LIME FROM INDUSTRIES . 5 . 809-315 Early use of gypsum — Source of some of the gypsum in soils — Gypsum poorer than lime on acid soils — Gyp- sum may yield calcium carbonate in the soil — Gypsum may furnish lime or sulfur as plant food — Factors de- termining the choice between gypsum and lime — Gyp- sum as a retainer of ammonia— Methods of applying gypsum — Gypsum as an oxidizing agent — Gypsum may sometimes aid nitrification —Gypsum a renovator of alkaline soils —Effect of gypsum on the solubility of lime — Gas-lime and lime from other industries. CHAPTER XXII MAGNESIA AS A FERTILIZER : : : : . . 816-332 Functions of magnesia in plants — Conflicting ideas as to the action of magnesia — Loew’s theory concerning magnesia — Ratios of lime and magnesia in different soils — Variations in magnesia content of different parts of the same plant — Concerning the alleged toxic action of magnesium chlorid — Danger from using caustic mag- nesia and burned and hydrated magnesian lime — Solu- bility of magnesium carbonate in its relation to -practice and experiment — Ranges in lime and magnesia content of plants without material difference in yield — Desirable lime and magnesia ratios in soils and culture solutions — Sources of magnesia. CHAPTER XXIII Sopium Sats j : ; ; ; , - : . 3838-350 Mineral sources of sodium salts — Black alkali — Quan- tities of common salt injurious to crops— The presence of soda in plants—Sodium salts as indirect manures — Concerning the benefit to crops from applying sodium salts — The effect of sodium salts dependent on various conditions — Influence of sodium salts on the conserva- tion and movement of soil moisture —The effect of sodium salts on osmotic pressure — The possible phys- CONTENTS xxi PAGES iological and manurial functions of sodium salts— Re- sults by Jordan and Genter — Soda in connection with diastatic action — Atterberg’s experiments with soda — Experiments at Bernburg, Germany — The Rhode Island experiments — Practical significance of soda in agri- culture. CHAPTER XXIV Iron AND MANGANESE . , ‘ é 3 : ‘ . 9851-356 Iron in its relation to plant growth — Manganese in plants and soils — Manganese as a fertilizer — Manganese in Hawaiian soils — Plants unlike in endurance of manga- nese — Variations in manganese content of plants— Effect of manganese on enzymes — Manganese increases many crops— Roots change the oxidation of manganese — Manganese may aid chlorophyl development. CHAPTER XXV Cuiorin, Sutrur, Sitica, Carson Disutrim, ToLurEnsn, AND OTHER MISCELLANEOUS SUBSTANCES. é . 857-366 Chlorin — Sulfur— Sulfur may become depleted in soils — Relation of sulfur and phosphorus in plants and soils — Need of sulfur should be investigated — Silica in plants — Suggested functions in plants— Silica may re- place other ingredients in-the ‘‘ luxury consumption ’? — Silica deposition checks sap diffusion — Carbon disulfid often increases crops — Reasons suggested for the benefit to soil from using carbon disulfid — Treatment of soils with carbon disulfid costly — Carbon disulfid cures cer- tain vetch, clover and alfalfa ‘‘sick’’ soils — Carbon disulfid not the only unusual compound to benefit soils — Disinfectants, like heating, destroy soil amebe — De- struction of soil protozoa may explain benefit from soil ‘¢ firing’? and deep plowing — General applicability of soil disinfection doubted by Loew — The chlorid of lime treatment of soil tried by Loew. INDEX . 2 ; 2 2 5 - ; 3 : , 367 = a i} “> s FERTILIZERS CHAPTER I HISTORICAL INTRODUCTION AccorpDING to the earlier conception of the term “manure,” it meant anything which when applied to the soil will render it more productive. In fact, certain very early English writers referred to the benefits of tillage as a manuring of the land. The use of the dung of animals, and of chalk, marl, ~ wood-ashes, and certain other substances for increasing the productivity of the soil, was known not only to the early Greeks and Romans but apparently also to the Chinese, whose employment of them for such purposes probably far antedates all human records. Indeed, Mago, the king of Carthage, in his work on agriculture, which won for him from his enemies, the Romans, the designation ‘‘Father of Agriculture,’ wrote of the value of bird manure, praising especially that of pigeons, and Cato (born 234 B.c.), the first Roman agri- cultural writer, gave to bird manure the first place. The manurial effect of various miscellaneous substances, and of certain legumes, was also well recognized not only by the agricultural writers Varro (39 B.c.) and Columella (50 a.p.), but even by the poet Virgil, for the latter, in speaking of ashes and dung, says : — ‘* But sweet vicissitudes of rest and toil make easy labor, and renew the soil. ‘* Yet sprinkle sordid ashes all around, and load with fattening dung the fallow ground.”’ B 1 2 FERTILIZERS During the dark ages, following the decline of the Roman Empire, practically all records of the use of lime and of other manures are lacking. The knowledge of their value was, however, presumably perpetuated by the studious inmates of the monasteries. Already in the sixteenth century a revival of the knowledge of manuring had begun, as shown by the writings of Bernard Palissy. Even Jethro Tull, the early English writer who con- tended that manures are unnecessary if the land is suffi- ciently tilled, was hardly more radical in his day than a certain recent writer who asserted that the chief func- tion of fertilizers was to improve the physical condition, and later, that it was to render innocuous various toxins of the soil. 1. Chemistry throws new light on the subject of manur- ing. — A true understanding of the fundamental princi- ples of manuring was made possible only through the aid of chemistry, although more or less general specula- tion on the subject had long existed, a fact well illustrated by many of the earlier English agricultural writings. One of the first steps toward a rational understanding of the problems of plant nutrition was the discovery by Priestley, in 1772, that combustion and the respiration of animals deteriorate the air and lessen its volume, but that plants can render it again capable of supporting com- bustion. This observation, coupled with his discovery of oxygen, led to the recognition of the fact that the bubbles already observed by Bonnet on leaves when they were immersed in water, were chiefly oxygen. It was then shown by Ingenhaus that these phenomena were caused by the action of sunlight, and Sennebier established the fact that the oxygen evolved by plants resulted from the decomposition of the carbon dioxid already taken up from HISTORICAL INTRODUCTION 3 the air, a fact demonstrated in a quantitative way by De Sassure. The last investigator showed that carbon, associated with the elements of water in the proportions represented by carbohydrates, such as starch and sugar, constitute the chief weight of plants. It was De Sassure, likewise, who recognized nitrogen as a plant constituent, and also the source and value of the ash ingredients. He supposed that the element nitrogen was derived either from the organic constituents of the soil or from ammonia present in the air. The idea that the ash constituents are of special value to the plant was also held by Sir Humphrey Davy. Several writers, including Thaer, added their contribu- _ tions to the accumulated knowledge of plant nutrition; but it remained for Boussingault to make the first syste- matic field experiments. His carefully conducted re- searches substantiated the accumulation of far more carbon in the plants than could have been derived from the soil. He also showed that more nitrogen was removed in the crops than was supplied in the manure. 2. The views of Liebig. — Notwithstanding the inves- tigations of those who had preceded him, Justus von Liebig soon became the great central agricultural figure, for in 1840 he maintained that if plants are supplied with the small quantity of mineral constituents of the ash, the remainder of their substance can be drawn from the air. It appears that Liebig was in error concerning the equal importance of the elements of the ash, also as con- cerns the analysis of the ash being a safe guide in manuring, and in respect to the mode of assimilation of the nitrogen. He also erred as to the possibility of certain elements replacing others which were somewhat similar, as, for example, in the supposed possibility of the complete - 4 FERTILIZERS replacement of potassium by sodium. It is now of interest to note, however, that the latest researches on this subject by Wilfarth and his co-workers in Germany, and by Wheeler and Hartwell and their co-workers in Rhode Island, uphold the idea of the partial replacement of potassium by sodium, in connection with the whole or a part of some one or more of its functions in the case of at least certain classes of plants. Another ‘question concerning which Liebig was gravely in error was that of the nitrogen supply of plants. He supposed, with others, that the amount of ammonia in the air was much greater than is actually the case, and that this supply was main- tained or even augmented with great practical benefit by the ammonia escaping into the air in the course of the fermentation of nitrogenous manures. It was in fact in this way that Liebig supposed that such manures were helpful to plants. 3. The early work of Lawes and Gilbert. — Many of the views expounded by Liebig were discredited by John Ben- nett Lawes (later knighted) of Rothamsted, England, who made a number of experiments on his own account. When in 18438 John Bennett Lawes associated with himself Dr. Joseph Henry Gilbert, a former student of Liebig’s, he took the first great step in systematic agri- cultural experimentation by the establishment of the Rothamsted experiment farm, upon which they conducted the painstaking researches which have become classic in the annals of agriculture. The subsequent experi- ments at Rothamsted, in which the American, Pugh (afterwards President of the Pennsylvania State College), was associated, appeared to disprove the supposed assim- ilation of atmospheric nitrogen which Ville and others believed to have observed. In fact, in the course of the HISTORICAL INTRODUCTION 5 experiments at Rothamsted in which the soil was sterilized, without thought of the consequences, it was concluded that the gain in nitrogen by legumes was due merely to their great feeding range by virtue of sending their roots so deeply into the soil,—a conclusion which for several years received world-wide acceptance. 4. Assimilation of atmospheric nitrogen by plants. — Notwithstanding the general acceptance of the idea that plants could not assimilate nitrogen directly from the air, the fact was nevertheless shown by Atwater! in 1884 in experiments with peas, which were grown in unsterilized soil in pots under such conditions that subsoil was elimi- nated, and not only all of the nitrogen of the soil, seed, and fertilizers was known, but also the nitrogen in the resulting plants could be determined definitely. Similar experiments were in progress at the same time by Hellriegel and Wilfarth? at Bernburg, Germany, which supported fully the conclusions of Atwater. The German investigators went indeed far beyond all who had preceded them and, by a series of experiments extending over a period from 1883 to 1888, established the fact that such assimilation of atmospheric nitrogen is due to the inter- vention of microdérganisms existing in symbiotic relation- ship in the nodules on the roots of certain legumes. It has since been shown that even a few plants belonging to other families, as, for example, the alder, also assimilate atmospheric nitrogen. 5. Other facts established by Lawes and Gilbert. — The honor nevertheless belongs to Lawes and Gilbert of estab- lishing the dependence of many of the common agricul- 1 Am. Chem. Jour., 6 (1884-1885), pp. 365-388. 2 Untersuchungen iiber die Stickstoffnahrung der Gramineen und Le- guminosen, Berlin, 1888. 6 FERTILIZERS tural plants on a supply of combined nitrogen, —a fact confirmed by the close relationship of the yields to the quantities of this element added in available form to the soil. It had been held, on the contrary, by Liebig that certain very leafy plants, represented by the common root-crops and clover, can flourish independently of nitrogenous manures (a fact since established for the clovers), and are able to draw their supply from the nitro- gen of the air. The field experiments of Lawes and Gilbert also demonstrated the prime importance of potash and phosphoric acid as manures, in contrast with the other constituents of the plant ash. These conclusions were of fundamental importance to agriculture and paved the way for the development of the present enormous fertilizer industry. Other’ experiments in progress at the same time by Boussingault, Stohmann, and Knop on the growth of plants in various nutrient solutions supplemented the work at Rothamsted and placed the question of plant nutrition on a substantial and scientific basis. It is an interesting fact that by this work of various investigators in the preceding century there was afforded the first satisfactory explanation of the beneficial effect fellowing the addition to the soil of a whole series of waste nitrogenous materials and substances of other kinds, the utilization of which, in connection with crop production, was recorded in England as early as 1653, and had no doubt been known already for many centuries. 6. The utilization of nitrates and guano. — The im- portation of nitrate of soda and of Peruvian guano into England for manurial purposes was begun about 1838 and 1840 respectively, although the value of nitrate of potash in connection with the growth of crops was surely known as early as 1669. HISTORICAL INTRODUCTION 7 7. Employment of ammonium salts. — The ammonium salts were supposedly first employed as manures as a result of the work and writings of De Sassure and Liebig on the utilization of ammonia by plants. Their use by Lawes, however, antedates the appearance of Liebig’s memorable paper on the subject in 1840. The systematic trials of a mixture of ammonium chlorid and of ammonium sulfate at the Rothamsted experiment station date from the year 18438. 8. The manufacture and use of superphosphate. — The employment of mineral phosphates, in a limited way, was begun in 1842 when Lawes took out his patent for the manufacture of superphosphate, but they were not to be had in any considerable quantity until three years later, when coprolites were discovered in England. 9. The German potash salts. —It is a noteworthy fact that the common salt manufacturers in certain parts of northern Germany were long troubled by supposedly worthless materials consisting of mixtures of crystalline salts of potassium chlorid, potassium sulfate, and corre- sponding salts of calcium and magnesium which were associated with some common salt and were found over- lying the purer rock-salt deposits. These materials were considered so objectionable and they interfered so se- riously with the common salt manufacture that they were given the collective name of ‘‘ Abraumsalz,” which desig- nates something to be taken out of the way. In or about the year 1860, however, the use of these salts for agri- cultural purposes was begun, — a step which has led to the present enormous output of kainit, muriate of potash, double manure salt (chiefly sulfate of potash and sulfate of magnesia), and of high-grade sulfate of potash, the 8 FERTILIZERS world’s supply of which practically all comes at present from the German mines. 10. The manufacture of basic slag meal. — Another notable advance in the development of the fertilizer in- dustry resulted from the discovery in 1879 by Thomas and Gilchrist, in England, of a method by which phosphatic iron ore could be effectively freed of its phosphorus in connection with the Bessemer process for the manufacture of steel, and whereby the resulting phosphatic slag was transformed into a valuable fertilizer. It has been stated that the same process was discovered independently by Jacob Reese in the United States. This phosphatic by- product is known under the names ‘‘ Thomas phosphate,” “Thomas meal,” “ basic slag meal,’ and the like. The use of this material has already reached enormous pro- portions in Europe, and it is being exported in considerable quantities to America, Egypt, and elsewhere. 11. New processes for combining atmospheric nitrogen. — Another important advance in the fertilizer industry has been brought about by the recent discovery by Frank and Caro, of Berlin, Germany, of commercially successful methods for the manufacture of calcium cyanamid by the utilization and combination of atmospheric nitrogen through the agency of calcium carbide. A still further step in advance in connection with the nitrogen fertilizer problem has resulted as a consequence of the discovery of a method by Berkeland and Eyde by which, by the aid of a powerful electric current, atmos- pheric nitrogen can be combined and united with calcium to form calcium nitrate. In Germany a process has also been devised by which hydrogen and nitrogen gases are made to unite under pressure and form ammonia by the aid of catalytic agents. HISTORICAL INTRODUCTION 7] 12. New catalytic and other fertilizers. — Space will not permit the mention of the many other new processes for the treatment of low-grade crude phosphates, feldspar, and similar materials, in order to increase their avail- ability, and of the series of so-called catalytic fertili- zers, such as certain manganese and zinc salts. Whereas it has seemed with each new discovery that the limit of human invention and accomplishment might have been reached, the recent progress doubtless only foreshadows still greater steps in the immediate future. ; CHAPTER II NIGHT SOIL Tue term ‘night soil”? has long been applied to human excrement for the reason that it was often customary, before the introduction of sewers, to remove it from cities and towns during the night. Human excrement is exceptionally rich in nitrogen and phosphoric acid. This is due not only to the nature of the food consumed, but also to the high degree of diges- tibility of the non-nitrogenous constituents of the diet, as compared with the coarser feeds consumed by the do- mestic animals. By the fermentation of the excrement great losses of nitrogen may result. 13. Conservation of night soil now'less necessary. — Owing to the rapid consumption of the natural supply of nitrate of soda, the fear was expressed quite recently that through the drain upon the land occasioned by the great numbers of people living in cities, and the almost universal waste of their excrement in the sewage, a nitrogen famine might result. Fortunately, this fear has been dispelled by the more recent discovery of economical methods for the production of calcium cyanamid, calcium nitrate, and ammonia from the in- exhaustible supplies of limestone, atmospheric nitrogen, and hydrogen. Danger to health. — One of the great objections to the use of human excrement as a manure is that it is often a 10 NIGHT SOIL Py great source of danger, on account of its being a ready medium for the conveyance of the organisms which cause various types of human disease. The necessity of providing a safe place fo the deposition of human excreta at a distance from the abiding place of man, is even set forth in the Bible Deuteronomy 23, verses 12 and 13). 14. Amount of urine produced per person. — Ac- cording to Heiden, a single individual produces in the course of the year about 1000 pounds of excrement, having a usual fertilizing value of from two to three dollars. It was found by Lecanu, in experiments with sixteen persons of different ages and sexes, that the excretion of urine, per twenty-four hours, ranged from 525 to 2271 grams. In experiments conducted on himself, Lehmann found, in a fourteen-day test with a mixed diet, that the daily excretion of urine amounted to from 879 to 1384 grams; and in the course of a twelve-day vegetable diet, it fell to from 720 to 1212 grams. Based upon these and other data, it is probably safe to estimate the average daily excretion of urine, per capita, at about 1200 grams (about 4.2 pounds). _ The solid matter in human urine has been found, based upon the work of several investigators, to range from about 34.5 to 87.4 grams per day, though it is said to vary with the different nationalities. This variation may, however, be due to temperature and other climatic conditions, rather than to constitutional differences. 15. Chemical composition of human _ urine. — The following percentages, given by Lehmann, represent the relative quantities of some of the more important con- stituents of human urine : — re FERTILIZERS + Ex om | ag Ria With: aynaixedudicti. sla. vim. 32.0 1.18 12.8 With an animal diet ... . 53.2 1.48 7.3 With a vegetable diet . . | . 22.5 1.02 19.2 With a nitrogen-free diet . . . 15.4 0.74 ae. k It appears therefore that the urine varies greatly in com- position, as well as in amount, according to the diet of the individual. It has been found that the percentage of nitrogen in the urine of children eight months old is about 0.15; in that of men 21 years old, 1.02, and in the urine of men of 46 years, 1.57 to 1.84. Based upon an average of 1200 grams of urine per twenty-four hours per individual, the average daily excretion of nitrogen in the urine would amount to 13.36 grams. The quantity of non-combustible salts is least in the urine of children, followed in turn by the urine of women, aged people, and men. The variations, however, in indi- vidual cases, and within these groups are very great. The chief constituents of the ash of urine, named in order, are chlorin, soda, potash, phosphoric acid, sulfuric acid, lime, magnesia, and iron oxid. Slight amounts of in- soluble matter make up the remainder. 16. The amount of solid excrement per individual. — The average quantity of solid excrement, per day, as found by Lawes and Gilbert, for boys under sixteen years of age, was about 108 grams; for men between 16 and 50 years, it was about 152 grams; and for men over 50 years of age, about 226 grams. The dry substance ranged NIGHT SOIL 13 from 27.4 to 42.3 per cent; it was found to be greatest in the case of old men. The amount of nitrogen present in the average daily excretion of the solid excrement of boys was 2.34 grams, of men 1.94 grams, and of old men, 0.321 gram. The quantities of ash were 3.69, 4.23, and 8.32 grams, respectively. In the ash the phosphoric acid has been found to range from about 31 to 43 per cent, the potash from about 6 to 21 per cent, lime from about 17 to 27 per cent, and magnesia from about 10.5 to 15.5 per cent. Heiden gives the following as the average quantity of both solid and liquid excrement per person daily : — SoLip Liquip Tora GRAMS GRAMS GRAMS otquantity < -..0./0 5.) = +). 1s3.0 1200.0 | 1333.0 Rurlguinablerine et 1 0/6: tee wees 510); 64.0 94.0 Organic matter. . . Mace 25.9 50.0 75.5 Nitrogen (in organic adhe Ris 2.0 a 14.2 Ash. . LE ot: 4.5 13.0 Lio PP ohoric head on panies BUS AU ve: 1.6 1.8 3.4 rereasiie (ire rastia res: ho oe A ee oe 0.7 22 3.0 17. Former methods of disposal in Europe were bad. — In Europe, generally, the conditions connected with the disposal of human excrement were, until a comparatively recent period, extremely bad, and even after the construc- tion of sewers emptying into the most accessible streams, the situation became highly dangerous to the public health. In England this led to the appointment of a special commission to inquire into, and report concerning, the matter. As a result of this and of similar agitation in 14 FERTILIZERS other lands, the present efficient septic tank and combined precipitation and filtration systems have been evolved. 18. Orientals conserve human excrement carefully. — Japan and China have thus far led the world in the systematic saving and use of human excrement for agri- cultural purposes. It has been possible thereby in the past, not only to maintain the enormous population of those countries, which is five to six times as dense as that of certain of the chief countries of Europe, but they have also been able, since the opening of their ports, to export to other countries considerable amounts of human food. In view of the practical economies of the Oriental nations in this respect; and in view of the fact that the world seemed to be facing a future nitrogen famine, many sys- tems for the preservation of human excrement have been devised from time to time. Owing, however, to the present methods of transforming the inexhaustible nitrogen supply of the air into available plant food in an economical way, it is unnecessary to devote space here to their description, from the standpoint of the conservation of nitrogen, more than by way of the briefest historical reference. 19. The conservation of human excrement in Paris. — The first police ordinance of the city of Paris, relating to the disposition of human excrement in a secret vault or similar place in each house, dates from 1348, but it was not until 1583 that a penalty for such an omission was provided. Regulations for the construction of such receptacles were made in 1809 by a decree of Napoleon, which was renewed in 1819. From 1781 to 1849 the human excrement of the city of Paris was deposited in an abandoned suburban quarry from which source the offensive odors penetrated a con- NIGHT SOIL 15 siderable portion of the city. As a result, provision was finally made for its disinfection and for effecting a separa- tion of the liquid and solid excrement. The former was then conducted into cisterns just outside of the city, from whence it was pumped to a more distant point, to which the solid excrement was at once conveyed by boat. Here the mass was left in open beds for several months. After the liquid portion had been clarified, it was utilized for the manufacture of ammonia. The remaining solid matter, after drying for a time in the beds, was further dried in the field, and then sold under the name of “ poudrette.”?” A part of the excrement was, however, still turned into the canals and found its way into the river Seine. Still later, after it was found that the method of disposal just described was not economical, the Seine became the receptacle for the entire mass of this material. The condi- tions which arose in consequence were so serious that a commission was appointed to investigate the entire subject, and, as a result, a modern filtration system was adopted. In the meantime in Lyons, in the south of France, and here and there in England, attention had already been given to saving some of the human excrement for agri- cultural purposes. The history of the situation in Paris is typical in many respects of the steps taken in other European cities, which have finally resulted in the present methods of municipal sewage disposal. 20. ‘“‘ Poudrette’’ from human excrement. — One oi the products sold under the name of “ poudrette”’ is prepared by the Liernur process, which consists in adding to the excrement sufficient sulfuric acid to bind the am- monia, after which the mass is evaporated in a vacuum until it reaches such a consistency that it can be completely 16 FERTILIZERS dried by other means and finally reduced to a powder. It happened, unfortunately, that the tendency to introduce foreign material, by way of adulteration, brought such poudrette into more or less general ill repute. 21. Treatment of excrement with burned lime. — Another but more wasteful process for the utilization of human excrement consists in treating it with burned lime. This method is said to have been first proposed by Payen and then by A. Miiller, and upon it is based the system of Mosselmann and Miiller-Schiir. By this pro- cess the ammonia which has been formed previously in the mass is lost. It is therefore important that the excre- ment be treated in as fresh a state as possible. Mossel- mann used two parts by weight of burned lime to one of moist excrement, and the final volume amounted to two and one-half times that of the lime employed. In this process 100 parts by weight of lime volatilize about 25 parts of water and bind chemically and mechanically about 50 parts more, thus producing a product which is so dry that it can be readily handled and transported, and the heat generated is sufficient to destroy pathogenic organisms. Such a system was in use recently in con- nection with the disposal of the excrement from tenement houses in certain manufacturing villages in Rhode Island, and the following is the composition of the product thus secured : — Per Cent Calctumijoxidas &. <3. 7: hee ee es Potassrom OxXids sci 0es ee as ee eee 0.09 Phosphoric acid), 2-0) -22 Aas see 0.91 Nitrogen Sybil coy kt oar oe, | a aa ea 0.43 One great objection to the material prepared by this process is that it is so excessively rich in lime that if it NIGHT SOIL i bag were applied regularly in sufficient quantities to supply the soil adequately with the other fertilizer ingredients, it would result in liming to excess. It may, however, be used frequently, for a time, on soils originally quite acid or, more infrequently, on those only moderately in need of jiming. To meet this objection in part, basic slag meal, potash salts, and other chemicals have sometimes been incorporated with it before placing it on the market. 22. The “ A. B. C.’’ and other methods of conservation. — In the absence of burned lime, alum, blood, and clay have been added to the excrement, after which the solid matter is dried, ground, and marketed under the name of “native guano.” This process takes its name “ A. B. C.” from the first letter of the name of each of the materials added to the excrement. A large number of other methods for the disposal of human excrement, by its transformation into poudrette, have been proposed from time to time. Some of these, like that of Teuthorn, involve evaporation and drying of the mass by natural means, whereas that of Thon was based upon evaporation of the water by means of artificial heat. The product as prepared by Thon at Stuttgart had the following composition :— Per CENT INGirEmenK* & os Bas ae ee oe A> 60 Phosphoerte acid. 2 “ssl en ie 100-120 PEEP els do beter deo hae A he ee ea aD In connection with the many other processes which have been employed for the same purpose at various ~ times, practically every conceivable absorbent and con- serving material has been used. 23. The novel method of Sindermann. — Among all of the methods proposed for the disposal of human excre- ment, perhaps the most novel is that of A. Sindermann, (e 18 FERTILIZERS which was adopted in connection with a hotel in Breslau, Germany. The excreta in this case were placed in a retort, where they were not only dried, but also subjected to dry distillation, in the course of which there were pro- duced illuminating gas, carbon dioxid, tar, oil, and am- monia. The valuable products were saved, as in the manu- facture of gas from coal; the gas, after the removal of the carbon dioxid and subjection to other purification, was used for illuminating purposes in the hotel. The resulting ash, with a content of 5.57 per cent of water, was found to contain 6.5 per cent of lime, 3 per cent of magnesia, 5.5 per cent of potash, and 8.6 per cent of phos- phorie acid. ; 24. Repeated use encourages undue leaf growth. — In general, it may be said that the continued use of con- siderable quantities of human excrement on land leads to unusual leaf growth, and, in the case of grass land, causes the lodging and consequent molding of some of the crop. Its excessive use also results in delaying the fruiting of other crops. The economical utilization of such mate- rial depends, therefore, upon limiting the amount used to that required to furnish the needed nitrogen, and on its being supplemented by proper amounts of potash and phosphoric acid. CHAPTER III THE DUNG OF FARM ANIMALS AND ITS PRESERVATION Tue term “farm manure” covers properly the dung of all the domestic animals kept on the farm, including the customary litter, night soil, peat, muck, leaf mold, other vegetable refuse, and composts. Barn-yard manure, as usually understood, relates to the dung of neat cattle with the usual litter. Stable manure is a term at present more commonly applied to the dung and litter from horse stables. 25. Influence of feed and age of animal on dung. — It may be stated that in general the dung of mature animals is of greater value than that of those which are making rapid growth; similarly, the dung. of cows not with calf and especially of those not producing milk, is richer than that of animals bearing their young or which are yielding large volumes of milk. The reasons for this are sufficiently obvious. It is assumed of course in such instances that the feeds are of the same general character. The dung of animals fed chiefly on grain, milk, and other similar materials is richer than that of those which subsist chiefly on coarse feeds, since it contains much more nitrogen, the most costly of all the manurial ingre- dients. 26. Influence of litter on manure.— The value of dung, as it has to be dealt with in a practical way, is very greatly affected by the kind and quantity of litter or 19 20 FERTILIZERS absorbents employed in the stables or yards. For ex- ample, the manurial value of cacao refuse or of peat or muck is of itself far greater than that of such materials as sawdust, shavings, and cotton waste, which are ex- ceedingly poor in nitrogen and in other less valuable manurial ingredients. 27. Collecting and caring for dung. — The method of collecting and of caring for the dung of the farm animals may affect its value greatly. If it is thrown out under the eaves of the stable, as was once a too common custom in the United States, most of the liquid or more valuable portion, representing about four-fifths of its total value, is likely to be carried away in the rain water. If, on the other hand, horse manure is allowed to lie in an undis- turbed pile in a barn cellar and to undergo fermentation until it reaches a ‘“‘fire-fanged”’ condition, great loss of nitrogen inevitably results. Serious, though less exten- sive losses of nitrogen occur through volatilization of ammonia either in the stable, cellar, or storage shed,on ac- count of the failure to use chemical agents for its retention ; but more particularly from leaving it either in small heaps or spread upon the surface of the ground for some time before the land is plowed. 28. Horse manure. — Because of the fact that the horse has but one stomach, and hence does not ruminate, it is not as well able as the sheep and cow to completely disintegrate and digest coarse feeds. On this account, and due to the presence of large amounts of fibrous material, horse manure is especially open and porous in character. Subject to ready fermentation. — On account of the less complete destruction of the organic compounds of the hay and grain in the course of the process of digestion, horse THE DUNG OF FARM ANIMALS 21 manure furnishes abundant organic food for the many microérganisms which promote decay, and hence it is especially subject to fermentations of various kinds. This fact is taken advantage of by its employment for the evolu- tion of heat in greenhouses and cold-frames. Owing to its loose physical character, horse manure is often mixed with cow manure, for certain purposes, with distinct ad- vantage to each. The solid portion. — The solid excrement of horses con- sists chiefly of the undigested portions of the feed, as- sociated with bacteria, minute quantities of biliary matter, and epithelial tissue, arising from the normal destruction of intestinal surfaces. The average composition of the solid manure is as follows: nitrogen 0.55 per cent, phos- phorie acid 0.30 per cent, and potash 0.40 per cent. The liquid portion. — The liquid excrement contains soluble phosphates, potash salts, and the organic meta- bolic products of the animal, such as urea, traces of crea- tinin (C,H;N;0), and, in the case of horses at rest, small quantities of hippuric acid. The urine of horses is more concentrated than that of the bovine species, and it con- stitutes about one-fourth of the weight of the total ex- crement. The following represents the average analysis of the liquid manure: nitrogen 1.35 per cent, phosphoric acid a trace, potash 1.25 percent. After being added to the solid portion the mixture has the following composition: nitrogen 0.7 per cent, phosphoric acid 0.25 per cent, and potash 0.55 per cent. Storage, and the use of litter. — Usually a greater percent- age of litter (bedding) is used for horses than for cows, on which account the manure as a whole is often of a more strawy character. The value of the manure is usually considered greater if straw or leaves are used for bedding ypu FERTILIZERS than if either shavings or sawdust is employed. This is, however, more likely to be true if the shavings are made from the wood of pine and of certain other coniferous trees. Experiments are nevertheless on record, showing that cow manure has been found to be equally as valuable with saw- dust litter as with a litter of straw or chopped corn stalks, when used for roses, carnations, chrysanthemums, and sweet peas. For certain reasons, manure without litter was preferred in special cases.! If horse manure is to be stored before its application to the soil, it should be compacted at once as completely as possible, and especial care should be taken to keep it moist. Amount of manure produced per animal. — It is estimated that every 100 pounds of dry matter in the feed of a horse will produce about 210 pounds of manure, containing about 77.5 per cent of moisture. Allowing in addition 6.5 pounds of bedding per day per horse, and allowing also for the manure usually voided outside of the stall, there would be available for use about five and one-fourth to six and one- third tons of manure per horse per annum. 29. Cow manure. — The manure of neat cattle, owing to their habit of ruminating and to the comparatively complete digestion afforded by their four stomachs, is far more compact than horse manure, and hence for many purposes is improved by an admixture of the latter. Nevertheless, in the preparation of soil for rose culture under glass, and for certain other greenhouse, garden, and farm purposes it is preferred, by many, unmixed with horse manure. Chemical composition. — The chemical composition of cow manure is much like that of horse manure, though 1Pub. Int. Agr. Inst. (Rome), Ottawa Branch, Bul. 2, No. 6, July, 1912. THE DUNG OF FARM ANIMALS 23 it is less concentrated, and it contains about one per cent of hippuric acid (CsHyNQs). Quantity voided per cow.— The quantity of manure voided by the cow is much greater than that produced by the horse, which compensates in a measure for the more dilute character of the liquid portion, when considering the total value of the yearly product of each. The quan- tity of manure excreted daily per cow, inclusive of the customary quantity of absorbents, is from twenty-five to thirty pounds greater than that produced by the horse. One pound of.dry matter in the feed will furnish about 3.84 pounds of manure. To this must be added the litter in order to show the total amount of manure produced per animal. An average cow, if properly fed, will excrete _ approximately 65 pounds of manure per day, about 25 per cent of which is represented by the liquid portion. It is obvious that there will be wide individual variations from these figures, dependent upon the weight of the cow and upon the character and digestibility of her feed. Proportion of the nitrogen voided. — About one-fourth of the nitrogen of the feed is appropriated by the cow for the manufacture of her milk product, and to replace hair and other waste, leaving another and less valuable fourth in the solid excrement, and one-half in the liquid manure. 30. Sheep manure. — The value of the manure produced by a single sheep in a year is small. The manure always contains less water than that of other domestic animals, the average content being about 74 per cent. Sheep manure is especially prized by many florists for use in greenhouses, due, doubtless, in part to its improvement of the physical character of the soil; it is also much sought in some localities for application to lawns and for the pro- duction of certain garden crops. Owing to the low water 24 FERTILIZERS content of sheep manure, it is liable to ferment easily and to lose some of its nitrogen as ammonia. The average composition of the mixed solid and liquid manure is as follows : nitrogen 0.95 per cent, phosphoric acid 0.35 per cent, and potash 1.00 per cent. Amount of manure produced by sheep. — At the Cornell agricultural experiment station, it was found that three sheep fed for thirty-three and two-thirds days produced a total of 723 pounds of solid and liquid excrement. The average of a large number of German experiments shows that for 100 pounds of dry matter of the feed there are recovered 48.4 pounds of dry matter in the excrement. In general, the multiplication of the dry matter of the feed by 1.88 and the addition of the litter will give approxi- mately the amount of manure. On the basis of 73 per cent of water in sheep manure, 100 pounds of dry matter of the feed would produce 183 pounds of manure; or, in other words, a sheep weighing about 60 pounds would consume about 2 pounds of dry matter daily, which, with an amount of litter such as is often used, would amount to about 1500 pounds of manure per year. 31. Hog manure. — As a rule, pel manure is of less interest than that of other domestic animals, for the reason that a large portion of it is often voided in the field. It varies also so widely in composition, owing to the diversi- fied character of the food consumed, that one cannot give a value to it within very definite limits. Assuming the food to be the same, hog manure will not vary widely from the composition of the manure of other animals. The average of a considerable number of experiments shows that for every 100 pounds of dry matter in the feed con- sumed there will be produced about 237 pounds of manure. The liquid manure of hogs which have been well fed often THE DUNG OF FARM ANIMALS 25 contains as much as 2 per cent of nitrogen. The solid excrement of hogs is very wet and decomposes less readily than that of horses and of sheep. A hog will void on the average from 12 to 15 pounds of manure per day, which is equal to from two to three tons per year. There seems to have existed among farmers a certain prejudice against the use of hog manure for certain crops, although there seems to be no satisfactory experimental basis at this time for definite statements on this point. 32. Hen and pigeon manure. — The manure of hens and pigeons differs materially from that of the more common farm animals, by reason of the fact that the excreta are voided in one portion, rather than separately in solid and liquid form. Chemical composition. — A number of analyses of fresh hen manure show the range in nitrogen content to be from 0.56 to 1.38 per cent; in phosphoric acid, from 0.35 to 1 per cent, with the majority ranging from about 0.47 to 0.92 per cent; and the range in potash is from 0.18 to 0.45 per cent, though the more common limits are between 0.25 and 0.4 per cent. Air-dry hen manure contains from 1.82 to 2.13 per cent of nitrogen, from 0.85 to 2.21 per cent of phosphoric acid, and from 0.35 to 1.11 per cent of potash. It is not an ideally balanced manure fer all purposes, and can usually be supplemented profitably by the addition of a liberal amount of acid phosphate and by a moderate quantity of muriate of potash or of kainit. When so employed, the results from its use, even in much smaller quantities than otherwise, are excellent. Both superior in their action. — The superior action of pigeon and hen manure may readily be attributed in part 26 FERTILIZERS to the fact that the liquid and solid manure are voided together, in consequence of which the metabolized nitro- gen is less likely to suffer loss by leaching than in the case of most other manures. Furthermore, it very quickly undergoes nitrification after its application to the soil. These manures are naturally richer in nitrogen and in other fertilizer ingredients than certain coarser manures, owing to the more concentrated character of the feeds consumed. In view of the foregoing circumstance, these manures contain less of the various organic materials which characterize especially horse manure, and hence furnish a smaller supply of the organic foods for the organ- isms which are especially concerned in denitrification and the liberation of nitrogen in a free state. Both manures need supplementing. — The adaptability of hen and pigeon manure to general trucking and garden- ing purposes would often be much increased, and the ammonia better conserved, if 12 to 15 pounds of acid phos- phate and 18 to 20 pounds of kainit, or 4 to 5 pounds of muriate of potash were added to every 100 pounds of the fresh manure.’ It might be still further improved by add- ing to each 100 pounds, 5 to 10 pounds of gypsum, or land plaster. 33. Amounts of litter used as absorbents. — The quan- tity of litter which should be used is not only dependent upon the class of farm animals concerned, but also upon the character of the food consumed; since watery foods and those containing a large amount of nitrogen cause an increased flow of urine. It is generally desirable to employ sufficient litter to keep the animals clean, by in- suring the absorption of the liquid manure. To this end it has been recommended that the amount for cattle per day should be 9 pounds, for horses 6.5 pounds, and THE DUNG OF FARM ANIMALS PA for sheep three-fifths pound. Stated in another way, the litter should. be equal, approximately, to one-third of the dry matter consumed. 34. Comparative absorbent power of litters for water and ammonia. — The ability of the litter to absorb liquid may differ widely from its capacity to hold ammonia, as shown in the following table :— | WateR RETAINED | AMMONIA ABSORBED By 100 Pounps or | By 100 Pounps or Kinps or MATERIAL MATERIAL AFTER DIFFERENT Ma- 24 Hours TERIALS ri Pounps Pounps Wheat straw ie Oe ae eer 220 0.17 SRD SUTAW 85 ee 285 —} Pea straw . 280 — Partially | Hecorisosed iE NGOS eeicioe eye oe te tac 162 — IDMead leaves. 25... 5. 200 — IRIE Hy eee ; 600 1.10 Needles of Baniftetoiis thoes ‘ 175 a= SIERO RR EA sd ae ee ae 435 0.05 Spenttan. . . aie; 450 —- Air-dried humous sails , or S276 Phosphoric acid . 3.76 3.35 It is evident from the foregoing that such guano should be bought and sold solely on the basis of its chemical analysis. 126. Bat guano needs supplementing. — In most cases these guanos must be supplemented by applications of potassium salts and by readily available phosphatic fertilizers, if they are to be used in the most economical way. CHAPTER VIII FISH, CRAB, LOBSTER, AND SIMILAR WASTES ’ Tue term ‘fish guano” is often applied to fish and fish wastes,. but since it is in no strict sense guano, as im- plied by the Spanish origin of the name, it is more properly considered under a separate chapter. 127. Fish long used as a fertilizer. — The use of fish and of fish waste as a fertilizer by people living near the ocean, or wherever fisheries flourish, has long been prac- ticed. In fact, the American Indian was no exception, for he had already learned to apply fish as a fertilizer for his maize when the Europeans first landed on the shores of North America. 128. Early catching of fish for fertilizer purposes. — As early as 1872 the catching of fish, which were employed for fertilizing the soil for both wheat and hops, had become quite an industry on the coasts of Essex, Kent, and Sussex, in England. The fish, which were very small, were a variety of herring (Clupea sprattus). They were sub- jected to a stamping and crushing process and were ap- plied to the soil without further preparation. 129. Special processes for preparing fish for fertilizer uses. — In 1853 Petlitt patented a process for the prep- aration of a fertilizer from herring. The nitrogen con- tent of this prepared material ranged from about 11.2 to 13.8 per cent. Shortly after the middle of the preceding century Ch. de Molon, who had already convinced himself by 86 y FISH, CRAB, LOBSTER, AND SIMILAR WASTES 87 practical trials on his estate on the coast of Brittany of the manurial value of the wastes from the sardine fisheries, conceived the idea of treating the material in such a way as to prevent its rapid decomposition and render it trans- portable to long distances. To this end De Molon as- sociated with himself Thurneyssen, and they erected a factory near Brest, in which to carry out the process. This, in brief, consisted in heating the fish with steam applied between the walls of a double-walled kettle at a pressure of three and one-half atmospheres (140° C.), after which it was pressed. In this process the amount of oil recovered from the top of the waste liquors repre- sented about 2 to 2.5 per cent of the fresh fish. The waste liquors, because of their high nitrogen content, some- times created a nuisance, on which account they were often evaporated, whereby the solid matter was saved. The remaining cake was passed through a machine which rubbed it into a thick dough, in which state it was taken to the drying room and subjected to a temperature of from 48° to 56° R., until it was ready for grinding, in final preparation for shipment. The dry product ready for marketing represented about 22 per cent of the original weight of fish. 130. Fish wastes in Japan.—In Japan herring are likewise utilized for the manufacture of oil and fish-scrap, the latter being used without further manipulation, in fertilizing tea plants, tobacco, cotton, and other crops. 131. Fish wastes in Newfoundland. — In connection with the Newfoundland cod fisheries, the heads, entrails, bones, and other waste portions of the fish, to the amount of 700,000 tons annually, were cast into the sea until De Molon sent his younger brother to the Island to erect a factory for the preparation of fish guano for export. 88 FERTILIZERS 132. Norwegian wastes from cod and whales. — In Norway fish guano is prepared from the wastes of the cod- fishing industry and from whales. The number of cod- fish said to be taken annually in that country amounts to from 18,000,000 to 20,000,000. A considerable number of factories are engaged in the preparation of the waste for fertilizing purposes. The finished product has a white to brown color and usually contains from 8.5 to 11 per cent of water, 8 to 10 per cent of nitrogen, and 12 to 14 per cent of phosphoric acid. 133. Methods of handling Menhaden in the United States. — The method of handling the Menhaden (a sort of herring also called pogys, Alsa menhaden) now prac- ticed in the United States, varies somewhat in the differ- ent works. Insome places the former method of unloading from vessels by means of tubs holding 33 barrels, or about 1000 fish, is still in vogue. By that method from 80,000 to 100,000 fish can be discharged per hour. The tubs are raised by means of a steam hoister installed on the steamer and used in raising to the deck the fish caught in the seines. In certain instances, also; they are raised by hoisters located at the dock. From the tubs the fish are passed to a re- ceiving box, from which they are taken into cars. They are then hauled up an inclined track by another hoister and delivered into wooden vats, well provided with steam pipes. Each of these vats holds about 20,000 fish. Here they are cooked until they are ready for pressing in power- ful hydraulic presses which leave a product containing from 50 to 60 per cent of moisture. The scrap is then either treated with sulfuric acid, in order to prevent its decomposition, or it is sun-dried on platforms. At present most of the factories are equipped with elevators which transfer the fish to the receiving boxes and conveyors at FISH, CRAB, LOBSTER, AND SIMILAR WASTES 89 the rate of 250,000 or more per hour, for each elevator in operation. From the elevator the fish are carried into iron cookers of various sizes, which are from 20 to 30 feet long, and from 2 to 3 feet in diameter. The fish pass through these cylinders, subjected to a continual steam pressure of 100 pounds to the square inch, at the rate of from 100,000 to 150,000 per hour; they then pass, by a conveyor, directly into screw presses of various sizes. The larger presses now in use have a capacity of 150,000 fish per hour. Upon leaving the presses the scrap is carried, largely by means of conveyors of various types, to the acidulated scrap storage or to the dryers, as desired. In some cases the scrap is treated with sulfuric acid and is then transferred directly to vessels lying alongside of those which are discharging the fish. 134. Fish waste treated with sulfuric acid. — Attempts have been made to treat the fish waste with considerable quantities of sulfuric acid, but this has proved to be a very difficult operation; and in but few instances is the char- acter of the fish products such that this treatment is considered practical. The amount of water in such treated material may range from 13 to 18 per cent, the total nitro- gen from 7 to 9 per cent, and the total phosphoric acid often from 11 to 12 percent. By this treatment two-thirds of the phosphoric acid is rendered immediately soluble in water. A part of the nitrogen may be changed into ammonia, and, under the usual conditions, about one-third of it is thus changed. 135. Chemical composition and utilization of whale products. — Fresh whale-meat contains about 44 per cent of water, 23 per cent of fat, 32 per cent of flesh, and 1 per cent of ash. In its undried condition it contains about 4.8 per cent of nitrogen, but when fully dried the nitrogen 90 FERTILIZERS content is about 8.7 per cent. The whale-bone, with a content of 3.84 per cent of water, contains 1.3 per cent of fat, 34.6 per cent of organic matter, and 60.2 per cent of ash. The nitrogen amounts to 3.5 per cent. In the man- ufacture of fertilizer from the bones and meat of whales, the fat content is so great that many difficulties are met in making the separation. The whale glue which is unfit for other purposes finds its way into fertilizers. It contains approximately 8.4 per cent of nitrogen and 3.2 per cent of phosphoric acid. Whale flesh, when dried and freed from fat, contains from 14 to 15 per cent of nitrogen. A so-called ‘‘ whale guano,” with from 7 to 8 per cent of nitrogen and 9 to 10 per cent of phosphoric acid, and whale- bone meal with 4 per cent of nitrogen and 21 per cent of phosphoric acid, have been offered in the market. 136. Availability and use of fish guano. — The avail- ability of the nitrogen of fish guano stands close to that of dried blood. Like all such organic nitrogenous materials, the nitrogen is not so quick in its action as that in nitrate of soda, potassium nitrate, or even in sulfate of ammonia. There are several important conditions upon which its transformation into nitrates and its consequent efficiency very largely depends; as, for example, the temperature, moisture, soil reaction, the fungi, and the bacterial flora of the soil. Because of the several conditions necessary to the transformation of the nitrogen of such materials into ammonia and eventually into nitric acid, it is usually best to incorporate it with the soil rather than to use it as a top-dressing. Though not absolutely nec- essary, it is desirable that fertilizer ingredients of this character, if applied in large quantities, should be incorpo- rated with the soil several days before the seed is planted. In this way possible injury to the plant seedlings, which FISH, CRAB, LOBSTER, AND SIMILAR WASTES 91 might arise in connection with the processes of fermenta- tion, may be avoided. 137. Fish guano requires supplementing. — Owing to the high percentage of nitrogen present in fish guano, it should usually be applied in conjunction with bone, or preferably with basic slag meal or with acid phosphate, or other superphosphates. It is usually important, also, that it be properly supplemented with suitable potassium salts. 138. Fish scrap may be employed without further treatment. — As a rule the fish scrap is sold directly to fertilizer manufacturers, but’ whenever it and the waste untreated fish or parts of fish are obtainable at low cost, near where they can be utilized, they can be employed advantageously by spreading them on the surface of the land and plowing them under as one would use _ stable manure. 139. The value of fish waste depends on the climate and soil. — It is reported by Kellner that in certain parts of Japan fish scrap, owing to the warm climate, moisture, and other conditions favorable to decomposition, is a quick-acting fertilizer; but in very cold countries, where the reverse conditions prevail, its action is slow and is especially unsatisfactory early in the spring. For many reasons such material is much better adapted for use on sandy or naturally open soils than on compact silts and clays. 140. Shrimps. — Along the coast of the North Sea there are found millions of shrimps (Crangon vulgaris), which, though prized as a great delicacy for human food, are used at times in great quantities in the manufacture of fertilizer. Since the product is relatively poor in phos- phoric acid, it is often supplemented by additions of bone or of other phosphatic fertilizers. 92 FERTILIZERS 141. The king-crab. — In the United States the king- crab (also known as horse-foot or horse-shoe; Limulus Americanus) has not only been utilized directly as a fer- tilizer, but it has also been dried, ground, and sold under the name of “‘ horse-foot guano.”’ It has often been used as an ingredient of various commercial fertilizers. In a dry state this material contains, as found by Voorhees, about 10 per cent of nitrogen, which apparently possesses a high degree of availability. According to Storer, it is necessarily poor in phosphoric acid, as is shown by the fact that the dried shells, after being freed of the flesh attached to the upper portions and to the legs, contained but 0.26 per cent of phosphoric acid. They contain only 0.06 per cent of potash, but the content of nitrogen has been found to be equal to as much as 12.55 per cent. 142. The common crab. — According to Storer, the common crab (Lupa dicantha Milne-Edwards) collected on the shore of Massachusetts was found to contain 3.6 per cent of phosphoric acid, 0.2 per cent of potash, and 1.95 per cent of nitrogen. 143. Lobster refuse. — The shells of ‘cooked lobsters (Homarus Americanus Milne-Edwards), are reported by Voorhees as containing, when dry, an average of 3 per cent of phosphoric acid, 20 per cent of lime, and 4 per cent of nitrogen. An analysis of lobster shells reported by Goessmann, shows that they contained 7.3 per cent of water, 4.5 per cent of nitrogen, 3.5 per cent of phosphoric acid, 22.2 per cent of lime, and 1.3 per cent of magnesia. 144. Star-fish. — In the case of fresh star-fish examined at the Rhode Island experiment station it was found, after rinsing with fresh water and removing the superficial moisture, that they lost, upon drying, 64.4 per cent of their weight. The mineral matter remaining after they FISH, CRAB, LOBSTER, AND SIMILAR WASTES 93 were incinerated, amounted to 20.3 per cent. The fresh undried star-fish contained 9.62 per cent of lime, 0.23 per cent of potash, 0.20 per cent of phosphoric acid, and 1.8 per cent of nitrogen. The value of these ingredients in a ton of fresh star-fish, based upon the recent ruling prices for lime and the other ingredients, would range from about $6 to $7.50 per ton. It is reported that on the French and Belgian coasts of the North Sea a mixture of certain mollusks with star-fish is employed as a manure, under the name “‘ Coquilles animalisées.”’ CHAPTER IX COMMON SLAUGHTER-HOUSE NITROGENOUS WASTE PRODUCTS Tue number of waste nitrogenous animal substances is so large, and they are so important, that they demand individual mention. 145. Dried meat meal. — Among the trade names which have been applied to various preparations of dried meat meal are ‘‘ animal matter,” ‘‘ dried meat,” “ azotin,” and “ammonite.” These materials are produced in the process of rendering dead animals, meat refuse, and as a waste product from the manufacture of meat extract. In the preparation of such extracts much of the phosphoric acid is removed, on which account certain Australian prod- ucts have been placed on the market mixed with bone meal. These contain about 6 per cent of nitrogen and about 13 per cent of phosphoric acid. The rendering process. — In the rendering process refuse bones and meat are placed in steel tanks where they are subjected for a few hours to a steam pressure of from 40 to 60 pounds, or higher. As a result of this treatment the fat is separated and the bones are rendered highly friable, in consequence of which they can be easily ground. After the removal of the hot liquors the fat rises to the surface of the liquid, where it solidifies upon cooling; the meat is also separated from the bones, after which it is dried and ground. 94 SLAUGHTER-—HOUSE WASTE PRODUCTS 95 146. All readily utilized by fertilizer manufacturers. — Before the manufacture of fertilizers had grown to its present proportions, these meat residues were readily avail- able to the farmer, but now that the supply fails to keep pace with the demands, the manufacturers of “‘ complete ”’ fertilizers readily absorb the entire supply. 147. Chemical composition of meat meal. — The amount of nitrogen in the best of the meat meals ranges usually from 13 to 14 per cent; though they may contain as little as 10 per cent, according to the amount of im- purities and moisture present. In addition to nitrogen the meat meals contain varying percentages of phosphoric acid, depending in amount upon their origin and the quan- tity of bone associated with the meat. 148. Availability of meat meal. — In the availability of their nitrogen, these waste meat materials stand, accord- ing to Wagner, somewhat behind dried blood, horn meal, and tender plants, and on about the same plane as nitrogen in fish guano, bone, and bone tankage; hence they stand in the next to the best group of organic nitrogenous ma- nures. 149. The nature of bone tankage.— Bone tankage consists of rendered or steamed bone associated with a considerable quantity of meat, cartilaginous matter, and other substances. It is prepared from the animal refuse secured from slaughter-houses and meat markets. 150. Composition of bone tankage.— Its nitrogen content may range from 4 to 12 per cent and its content of phosphoric acid from 7 per cent to approximately 20 per cent. In the United States six commercial grades are often recognized with 18, 16, 13.5, 11.5, 9, and 7 per cent as the respective minimum percentages of phosphoric acid. It is obvious that these are mere arbitrary subdivisions, 96 FERTILIZERS and that any one grade must range up to the next higher just as the highest of the bone tankages range up to the minimum of what is recognized in the trade as bone. 151. Value of bone tankage as a fertilizer. — The value of bone tankage as a fertilizer depends to a considerable extent upon its degree of fineness. The importance of this feature is greater, the larger the quantity of bone, and consequently the higher the percentage of phosphoric acid. It is probable that the fertilizing value of the nitro- gen in bone tankage does not differ materially from that in bone, fish, and meat meal, and it should logically stand between the first two. 152. Method of employment. — The best method for the employment of bone tankage is to introduce it into the soil in finely ground form, rather than to use it in a coarse condition or to employ it as a top-dressing. 153. Chemical composition of red dried blood. — The red dried blood, which differs from the black blood in its method of preparation, possesses ordinarily the higher commercial value, and usually contains from 13 to 14 per cent of nitrogen, though if imperfectly dried it may con- tain much smaller percentages. 154. Chemical composition of black dried blood. — Black dried blood as commonly offered in the market may range in nitrogen content from 5.5 to 12 per cent, and es- pecially good lots have been found to contain over 13 per cent. 155. Reasons for occasional low nitrogen content of blood. — The low content of nitrogen sometimes found in dried blood may be due to the incidental or intentional introduction, in the course of its handling and manufac- ture, of more or less bone and tankage. It may also be due to its adulteration with pulverized roasted leather, SLAUGHTER-—HOUSE WASTE PRODUCTS 97 pulverized peat, or other substances, the detection of which, by casual inspection, and even in some cases by chemical or other means, has heretofore been difficult or impossible. If the blood contains much tankage or bone, there will be much more phosphoric acid present than the small quantity normally associated with pure blood. 156. Chemical composition of the better commercial blood. — The better grades of commercial dried blood usually contain from 13 to 14 per cent of water, from 10 to 13 per cent of nitrogen, 0.5 to 1.5 per cent of phos- phoric acid, and from 0.6 to 0.8 per cent of potash, though it is ordinarily sold without reference to any- thing but its nitrogen content. 157. Crystallized blood.— What is known as “ crys- tallized ”? dried blood is produced by evaporation at a temperature of about 60° C., and it is capable of being redissolved. Owing to its cost, it is usually employed for industrial rather than fertilizing purposes. 158. Certain processes of preparing dried blood.—JIn the process of transforming blood into the dried market- able material, it is agitated vigorously and is at the same time treated with steam in a vessel with a perforated false bottom. As a result of the raised temperature, coagula- tion of the fibrin and albumen takes place, after which the slightly reddish liquid portion is withdrawn. After dry- ing, the blood is milled to a proper degree of fineness. The yield of dried blood is above 20 pounds per 100 pounds of the original material. The coagulation is often has- tened by the addition of a small amount of concentrated sulfuric acid. Sometimes from 2 to 3 per cent of pul- verized quicklime is added to the blood before flocculating. In consequence of this addition, any ammonia in the waste water is disengaged, and the material can then be dried in H 98 FERTILIZERS the air, if desired, with the result that a practically odor- less fine powder is produced. If blood is allowed to stand for some time, after adding from 1.3 to 3 per cent of lime, the mass will solidify and can be subsequently air-dried with ease and without under- going decomposition. In the process of drying and preparing dried blood, a mixture of iron sulfate, sulfuric acid, and sodium nitrate is often added. The coagulation in such cases is very rapid, and the material gives off no bad odors during the process of drying. It is not practical for this purpose to use solely the commercial iron sulfate, for if this is done there results a pasty mass which does not dry readily. In order to obviate this difficulty, a mixture of sulfate of iron and of alum is sometimes employed; also treatment of the blood with calcium carbonate (chalk) and peat; and precipitation with alkaline sulfates or phosphates and acid ferric sulfate. 159. Dried blood, if very fine, is highly hygroscopic. — The finer the blood is ground, the more hygroscopic it becomes, and when made excessively fine the water con- tent has been known to reach 27 per cent. This high moisture content is, however, not desirable in material which must be stored, for too much moisture is likely to lead to changes resulting finally in a loss of ammonia. 160. Availability of blood dependent upon soil condi- tions. — Dried blood is the best, or one of the best, organic nitrogenous fertilizers, but like others it is dependent for its efficiency upon the character of the soil. This is well shown by experiments made with it on upland silt loam soil, at the Rhode Island experiment station, in which the availability of the nitrogen in an excellent lot of black dried blood, containing slightly over 13 per cent of nitro- SLAUGHTER-HOUSE WASTE PRODUCTS 99 gen, was considerably less than one-half as great as in nitrate of soda, whereas after liming the soil, the avail- ability of the nitrogen rose to over 90 per cent of that in nitrate of soda. 161. Processes of preparing horn meal and hoof meal. —In the various manufacturing establishments where horn is employed, there is a large lot of waste material. The preparation of such horn waste, and of hoofs, for fer- tilizing purposes, is sometimes accomplished by subjecting them for about twelve hours to steam pressure, after which the material is dried and ground to a fine powder. It is then sold as horn meal and hoof meal. Another method of manufacture is to subject the materials to high tempera- tures, even frequently to the extent of slight roasting, after which they can be easily pulverized. In consequence of the loss of water in this process the nitrogen content is raised materially. 162. The chemical composition of horn meal.— A very pure sample of horn meal’is reported as containing 9,5 per cent of water, 87.4 per cent of organic matter, and 1.69 per cent of ash, in addition to small amounts of impurities. The amount of nitrogen present in horn (in keratin) is about 14.1 per cent, phosphoric acid 0.28 per cent, and lime 0.48 per cent. Certain English writers report the range of nitrogen in commercial samples of horn meal to be from 7 to 15 per cent. 163. Chemical composition of horn and hoof meal. — A sample of mixed horn and hoof meal, from a lot in which hoofs were used which had a small amount of bone adher- ing to them, was found by C. Peterson to contain 13 per cent of nitrogen and 5.5 per cent of phosphoric acid. 100 FERTILIZERS Samples are reported from France as containing from 16 to 17 per cent of nitrogen. The analyses of three different lots of hoof and horn meal are reported by Goessmann in which the minimum of nitrogen was 11 per cent and the maximum 15.5 per cent. 164. The nitrogen content of hoof meal. — The average nitrogen content of hoof meal is generally held to be about 12 per cent. 165. The efficiency of hoof meal. — Hoof meal in its natural condition is held by Voorhees, Murray, and others as being of little value, even though finely ground; and some authorities assert that even after steaming, the value of the nitrogen is still far below that in blood and tankage. It is nevertheless superior to leather, wool waste, and hair, and Heiden ranks it as a very effective nitrogenous fer- tilizer (Diingerlehre, 2, 746). 166. The adulteration of horn and hoof meals. — It is reported that horn meal and hoof meal are sometimes adulterated with ground nut shells and other difficultly recognizable sustances. On this account, in purchasing such materials, one should buy only on the basis of a guaranteed analysis. The adulteration may explain much of the discordant testimony as to the agricultural value of these materials, for it does not appear that the genuineness of the lots employed in certain experiments was always determined. 167. Preparatory treatment of waste leather. — Large quantities of leather waste are now said to be employed in the manufacture of ready-mixed fertilizers. In its preparation for such use a wet acid or ‘‘ chamber ”’ pro- cess, involving a simultaneous treatment of raw phosphates, is applicable, as it is under certain conditions to many of the other waste nitrogenous materials. Waste leather is SLAUGHTER-HOUSE WASTE PRODUCTS 101 also treated with steam, in the same way as hoof meal and horn meal. It is then dried and ground, or in lieu of steaming it is often roasted and ground. The value of such prepared leather, unless it is subjected to the “ cham- ber ”’ process, is very small in any case, although it is slightly greater if steamed than if roasted. Owing to the destruction of the tannin in the roasting process, the leather thus prepared is said to be selected as an adulter- ant of dried blood and of certain other high-grade nitro- genous substances, on account of the difficulty of its recognition. 168. The chemical composition of prepared leather waste. — The leather meal prepared by the steaming or roasting processes contains from 7 to 9 per cent of nitro- gen and from 0.5 to 1 per cent of phosphoric acid; al- though it may sometimes range slightly above or below these figures. 169. The availability of nitrogen in leather. — If em- ployed on a soil in which the conditions for nitrification are poor, the value of the nitrogen of roasted leather may be even less than one-hundredth as great as that of the same quantity in nitrate of soda; if, however, the condi- tions for nitrification are ideal, its value may rise to from 13 to 20 on the basis of 100 for the nitrogen in nitrate of soda. At all events, such leather is one of the least valu- able of the nitrogenous fertilizers. It is obvious, therefore, that roasted or steamed leather meal, if employed directly as a fertilizer, is not worth the cost of transporting to very great distances. It is, however, probable that by the sul- furic acid or ‘‘ chamber ”’ process a considerable part of the nitrogen is changed into sulfate of ammonia and that the organic residues remaining are also rendered still more available to plants. 102 FERTILIZERS 170. Treatment of leather with carbonates of the al- kalies. —It has been proposed by Reichardt to treat waste leather with carbonates of the alkalies. Before being subjected to such treatment, powdered leather was found to be soluble in hot water to the extent of but 15.8 per cent, but after being left in contact with a 5 per cent solution of sodium carbonate for several days, it was soluble to the extent of 28.8 per cent. This method of treatment has, however, apparently never found any exten- sive application in practice. 171. Leather really not so valuable as it appears. — The inefficiency of the nitrogen in leather meal, as com- pared with that in the better class of nitrogenous materials, is not shown adequately by merely the smaller weights of the resultant crops, since crops grown with the aid of an abundance of readily available nitrogen are often richer in that element, and hence possess a greater feeding value than those grown with poorer and less available materials, like leather. This is well illustrated by experiments by S. W. Johnson in which nitrogen in blood, at the rate of 20 pounds per acre, gave four times as great an increase in crop as the same amount of nitrogen in horn. The in- crease of nitrogen in the crop was also nearly twice as great in the former as in the latter case. With 40 and 60 pounds of nitrogen per acre, the same principle held true, although the proportionate increases were not the same as in the first instance. CHAPTER X OTHER MISCELLANEOUS NITROGENOUS SUBSTANCES A CONSIDERABLE number of plant residues and of other miscellaneous materials of somewhat uncommon occur- rence are often used for manurial purposes. These will now be considered. 172. Feathers.— Clean feathers, according to the analy- ses of Payen and Boussingault, contain 15.3 per cent of nitrogen. The sweepings from a feather warehouse, how- ever, contained but 6.25 per cent of nitrogen, indicating the presence of much foreign matter. Feathers decompose slowly in the soil, and hence they have a small positive value as a fertilizer, even without special treatment. 173. Hair bristles and wool.— The hair of various animals, the bristles of swine, and wool all contain es- sentially the same amounts of nitrogen as feathers. In other words, if free from all impurities, they contain from 14 to 15 per cent of nitrogen. After drying at 250° F., human hair has been found to contain 17 per cent of nitrogen. 174. Tannery hair. — Hair from tanneries contains more or less foreign matter and water, which lessen the nitro- gen content. The amount of nitrogen found in such hair ranges from 5.5 to 8 per cent, the average being about 6.5 per cent. Certain of the calcareous wastes of the tanner- ies, charged with organic matter derived from the cleans- 103 104 FERTILIZERS ing and preparation of hides, contain from 2.8 to 3.4 per cent of nitrogen. 175. Waste silk. — The nitrogen content of waste silk and silk rags ranges from 8 to 11 per cent of nitrogen, depending upon the purity of the materials. 176. Wastes from hares and rabbits. — In the prep- aration of the hair of hares and rabbits for the manufac- ture of hats, the ears, tails, legs, and irregular parts of the skin often accumulate in considerable quantities as waste matter. This material, according to C. Thiel, has been found to contain 7 per cent of nitrogen, 0.6 per cent of potash, and 1.7 to 3.1 per cent of pbosphoric acid. 177. Chemical composition of waste wool. — Wool waste may contain from 0.5 to 7 per cent of nitrogen, dependent upon the amount of water and of foreign matter which is present. The range in the water content is usually from 15 to 50 per cent. Various methods have been proposed for utilizing this and other nitrogenous materials. 178. Wool waste as a manure. — Wool waste has long been used in its natural condition as a manure for hoed crops and in preparation for seeding to grass; and, like coarse stable manure, it is best to spread it broadcast and turn it under with a plow. Its use is seldom to be recommended, excepting where the transportation charges and the cost of application are small. 179. Effect of superheated steam on wool waste. — When wool waste is subjected to high steam pressure, it assumes a liquid condition. Upon subsequent evapora- tion there remains a dark brown powder said to be very largely soluble in water and supposed to consist of leucin (CsHigsNO2), tyrosin (CoHiuNOs), and other related amid compounds. MISCELLANEOUS NITROGENOUS SUBSTANCES 105 180. Concerning Petermann’s tests of availability. — Experiments by Petermann, conducted in the field and in pots, have appeared to show that notwithstanding that the nitrogen of wool is rendered more available by the process of steaming, it is still much inferior to nitrogen in nitrate of soda. These experiments were made with spring wheat and with beets in conjunction, in certain cases, with phosphates, but without potassium salts. It is interesting, in view of the omission of potash, to note that the nitrogen in nitrate of soda appeared to possess relatively greater superiority for the beets than for the wheat. This, in the light of observations made by Hell- riegel, Wilfarth and others in Germany, and by Wheeler and Hartwell at the Rhode Island experiment station, indicates a probable direct or indirect manurial effect of the soda, the first or both of which would be expected to “be greater in connection with beets than with wheat. Owing to this failure to provide an abundance of potash and to recognize the possible beneficial alkaline effects arising from the residual sodium carbonate formed from the nitrate, too great value was doubtless attached to the nitrogen in nitrate of soda, and too little to the effect of steaming as a means of increasing the efficiency of the nitrogen of the wool waste. 181. Soluble wool waste not subject to loss by leaching. —It was found by Petermann that practically none of the soluble nitrogenous organic matter was lost from the soil by leaching, in which respect it possesses certain dis- tinct advantages in open soils. 182. Benefit from steaming not equally applicable to all other nitrogenous wastes. — Attention has been called by 8S. W. Johnson to the fact that the availability of certain materials, such as bones, tendons, and _ hide, 106 FERTILIZERS which yield glue, may be injured by steaming, in case the glue is not removed. This is said to be due to the cement- ing action of the glue, on account of which the decomposi- tion of the material in the soil is hindered ; nevertheless, horn, hoof, hair, wool, and certain other materials are benefited by the treatment. 183. The production of garbage tankage. — Garbage tankage is the product derived from the treatment of kitchen wastes, and it may be composed of materials of both vegetable and animal origin. The refuse is treated with steam at high pressure, as a result of which it is completely disinfected, and much of the water is expelled. This product is then extracted by benzene, which is sub- sequently recovered and used for the repeated extraction of new lots of material. The extracted residue is then screened, in order to permit of the recovery of the bones and of other miscellaneous materials, in separate portions. It is said by Storer that 30,000 pounds of kitchen waste have been found to yield by this process 1800 pounds of grease and 12,000 pounds of garbage tankage. In this process the vapors are condensed and passed into the sewers, and the various operations are said to be practically unaccom- panied by odors. 184. The fertilizer value of garbage tankage low. — Such garbage tankage is of rather low value as a manure. It is used by a few fertilizer manufacturers, some of whom fortunately submit it to the so-called “‘ wet cham- ber ” process, by which its value as a fertilizer is at least somewhat improved. . It usually contains from 2.5 to 3 per cent of nitrogen, 1.5 to 3 per cent of phosphoric acid, and from 0.7 to 1.5 per cent of potash. 185. The character of shoddy and felt refuse. — The MISCELLANEOUS NITROGENOUS SUBSTANCES 107 ’ term “shoddy,” as formerly used, referred to short frag- ments of wool rejected in various woolen industries. Now, however, the name is often applied to wastes of both silk and wool. 186. Chemical composition of shoddy and felt. — Shoddy usually contains from 4 to 12 per cent of nitrogen, the average content being about 6.5 per cent. A felt refuse examined by Goessmann was found to contain 5.26 per cent of nitrogen. It may therefore be classed as of about the same general character as shoddy. 187. The useof felt and shoddy wastes as manures. — Felt and shoddy wastes are highly esteemed as a manure for grapes and certain other fruits, and especially for hops. This is supposedly due to the fact that these crops do not require a large amount of nitrogen at any given time, but thrive best where the supply, though small, is continuous throughout the season. For such pur- poses shoddy is considered as one of the best substi- tutes for farm-yard manure, and in many cases it is even chosen in preference to the manure. From 1 to 2.5 tons of shoddy are considered equal to 20 tons of farm-yard manure. Shoddy not only exerts a direct manurial action, due to its high content of nitrogen, but it also improves very greatly the physical condition of certain soils. 188. The character of soot. — Soot consists chiefly of finely divided particles of carbon which are deposited in chimneys during the imperfect processes of combustion. On account of its finely divided physical condition, it condenses gases upon its particles to a high degree, and hence often becomes rich in ammonia which it has ab- sorbed from the gaseous products of combustion. 108 FERTILIZERS 189. The chemical composition of soot. — The nitrogen content of soot may range from about 0.5 to 6 per cent, the average being about 3.2 per cent. 190. Soot benefits physically. — Owing to its dark color, soot is supposed to cause soils upon which it is spread to absorb more heat, thus forcing the crop and creating conditions favorable to bacterial activity. When it is introduced into soils it also improves their physical con- dition, especially if they are of a clayey texture. 191. Soot rarely toxic.— A sample of soot has been reported in Europe which was found to be toxic to plants, due to the presence of pyridin or similar compounds, yet the almost universal indorsement of soot as a ferti- lizer shows that the presence of poisonous substances must be considered as most exceptional. 192. Light soot best. — The best soot is usually that which is the lightest in weight, and heavy weight indicates contamination with mineral matter of questionable value. The usual weight of a bushel of soot is about 28 pounds. 193. Insects and cocoons. —It has been found that certain insects yield as much as 19 per cent of fat, and that in their natural state they may contain from 3.2 to 8.41 per cent of nitrogen. In addition, the content of phos- phoric acid has been found to range from 0.6 to 1.5 per cent and the potash from 0.5 to 0.96 per cent. Certain of the richer of these insects, after the removal of the fat and complete dessication, yield a product containing as much as 14 per cent of nitrogen. The cocoons of the silk worm have been found to con- tain 1.82 per cent of phosphoric acid, 1.08 per cent of potash, and 9.42 per cent of nitrogen. 194. Peat and muck.— Peat and muck, though con- taining all of the usual mineral elements of agricultural MISCELLANEOUS NITROGENOUS SUBSTANCES 109 importance, nevertheless contain too little of any of them to be of practical significance as manures. Such vege- table residues are valuable as soil amendments by virtue of the large volume of organic matter which they contain, and on account of their nitrogen, although the latter is but very slowly available. The composition of muck and peat varies widely, dependent upon whether they are derived from trees, shrubs, grasses, mosses, or other forms of plant life and also according to the quantities and kinds of mineral matter which they contain. Air-dry peat may be assumed to range in nitrogen content from 1 to 2.5 per cent, according to the materials of which it was formed. 195. Peat and muck especially valuable on light soils. — Peat and muck are especially applicable for use on light, sandy, and gravelly soils which leach badly and lack vegetable matter. On such lands these materials may effect a veritable transformation in productiveness, es- pecially in seasons when the rainfall is light, or when it is unevenly distributed, but not always if excessively dry. 196. Salt and fresh muds. — Dried mussel mud is reported by Goessmann as containing 0.72 per cent of nitrogen and 0.35 per cent of phosphoric acid. Another sample of salt mud, with 53 per cent of water and 41 per cent of ash ingredients, contained 0.4 per cent of nitrogen. Fresh-water mud, with a moisture content of 40 per cent, contained 1.37 per cent of nitrogen, 0.22 per cent of potash, and 0.26 per cent of phosphoric acid. None of these materials is sufficiently valuable to justify hauling to a considerable distance, and they are often chiefly of use in improving the physical condition of sandy or gravelly soils. 197. Cereal and other seed by-products. — Among the various cereal and other seed by-products, cotton- 110 FERTILIZERS seed meal is probably the most important, from the fer- tilizer standpoint, of any which are extensively used in the United States. Notwithstanding the high feeding value of cotton-seed meal and the wisdom from the stand- point of national economy of feeding it first, and of using the resultant dung as a manure, enormous quantities of it are used separately for special manurial purposes and also as an ingredient of ready-mixed commercial ferti- lizers. It is used extensively, especially in the South, not only as a manure for cotton and sugar cane, but also for other crops, and it is one of the favorite sources of organic nitrogen, especially for tobacco. For this latter purpose enormous quantities of it are used in the Connecticut Valley, in the states of Connecticut and Massachusetts. 198. The composition of cotton-seed meal. — Owing to changes in the method of removing the oil, cotton-seed meal is not usually as rich in nitrogen as formerly, the lower limit for the decorticated meal being about 6 per cent, and the upper limit 7 per cent. The undecorticated cotton-seed meal contains about 4 per cent of nitrogen. In addition to nitrogen, cotton-seed meal contains about 2.5 per cent of phosphoric acid, and about 1.7 per cent of potash. 199. The composition of linseed meal. —Linseed meal and cake contain from 4.9 to 5.8 per cent of nitrogen, 1.2 per cent of potash, and 1.8 per cent of phosphoric acid. 200. The composition of malt sprouts. — Malt sprouts reach a limit of from 3.5 to 4 per cent of nitrogen, 2 per cent of potash, and 1.3 per cent of phosphoric acid. 201. The composition of castor pomace. — Castor pomace contains from 5.5 to 5.75 per cent of nitrogen, from 0.6 to 3.4 per cent of potash, and from 1.5 to, 2.25 per cent of phosphoric acid. MISCELLANEOUS NITROGENOUS SUBSTANCES 111 202. The composition of wet brewer’s grains. — Wet brewer’s grains contain 76 per cent or more of water, 1.2 per cent of ash, 0.9 per cent of nitrogen, 0.5 per cent of phosphoric acid, and 0.05 per cent of potash. 203. The composition of gluten feed. — Gluten feed contains usually from 4 to 5 per cent of nitrogen, but only 0.75 per cent of ash. 204. The utilization of the spent wash of distilleries. — The spent wash of distilleries of various kinds contains notable quantities of nitrogen. This represents a loss of 1 to 1.25 pounds of nitrogen, per 10 gallons of 100 per cent alcohol produced. The wastes from the distillation of beet sugar, molasses, and sucrate liquors contains’ 1.4 per cent of nitrogen and 0.9 per cent of salts. Attempts to recover these wastes by dry distillation are complicated by the tars and other products, difficult of purification. Many other methods of treating these liquors have like- wise been tested. 205. The process of Vasseux.— The process of Vas- seux, which is employed with gratifying results in France and Spain, consists in concentrating the wash and adding sulfuric acid, whereupon the potassium sulfate crystal- lizes out in the mass and is separated by decantation, filtration, and centrifugal treatment, yielding finally a product containing 75 to 80 per cent of potassium sulfate. The drying of the liquor is completed in vacuo, where- upon it is poured into trucks. After cooling, this residue is crushed and prepared for agricultural use. The final product contains 6 to 7 per cent of nitrogen and 6 to 7 per cent of potash. It is almost wholly soluble in water, and is said to be an excellent fertilizer. The usual yield is 300 pounds of fertilizer per ton of the molasses treated. 112 FERTILIZERS 206. The process of Effront.— A process devised by Effront consists in converting the organic nitrogen of these spent liquors into ammonia by the employment of amidase in an alkaline medium. The ferment is then separated for further use, and the ammonia is won by dis- tillation. A butyric acid ferment and others separated from a garden soil have been similarly employed by Effront in treating spent wash. By this method there was secured from 814 gallons of molasses, not only the cus- tomary 22 gallons of alcohol, but also 77 pounds of pure volatile fatty acids. CHAPTER XI THE AVAILABILITY OF ORGANIC NITROGEN AND FACTORS AFFECTING IT In determining the availability of organic nitrogenous substances, the efficiency of their nitrogen is usually com- pared with that in nitrate of soda, which for the sake of convenience is usually placed at 100. 207. The factors of temperature and moisture. — In such work temperature and moisture conditions, as well as the texture and chemical reaction of the soil, are im- portant factors, for it is well recognized that in warm climates, especially on open soils, and for plants having a long period of growth, comparatively inert forms of nitro- gen act much better than in temperate climates and on compact soils. 208. Effect on the soil reaction. — It is coming to be more generally appreciated than formerly that soils are — rendered less acidic or more alkaline by sodium nitrate, whereas certain organic nitrogenous substances may exert an appreciable ultimate acidic effect upon the soil by virtue of the nitric acid resulting in the course of their de- composition. 209. Effect of large applications at the outset. — In case a very heavy application of nitrate of soda is made at the outset, it may in some cases interfere, for a time, with the physiological functions of the plant to such an extent that even if it actually takes up more nitrogen, I 113 114 FERTILIZERS the total quantity of dry matter may finally be less than that produced by a like amount of nitrogen in certain organic materials, which are more slowly available. For this reason deductions as to the availability of the nitro- gen should properly be based upon the nitrogen actually taken up by the plants, rather than merely upon the total dry matter produced. 210. Employment of different amounts of nitrogen. — It is also important in making such availability tests to use two or three series of experiments in which different amounts of nitrogen are employed. 211. Other elements must be supplied generously. — Care should also be taken to determine definitely by experiment whether enough of all the other fertilizing ingredients has been employed to insure that nitrogen is really made the factor which limits growth. The point just mentioned is especially important in view of the now well-recognized physiological and other func- tions, performed by sodium salts when potash is lacking, for if the supply of potash were insufficient, the greater yield produced by nitrate of soda, in comparison with organic nitrogen, might be due to a considerable extent ‘to the soda having performed some part of some of the functions of potash. If this were not guarded against or anticipated, the conclusion might be drawn that the nitrogen in other materials was relatively much more in- ferior in comparison with that in nitrate of soda than the actual facts would justify. 212. False conclusions a result of neglect of con- ditions. — A careful study of the literature of the subject reveals cases in which comparisons of nitrogenous sub- stances have been made in which no potassic fertilizers whatever were employed, nor was evidence sought to THE AVAILABILITY OF ORGANIC NITROGEN 115 show that sufficient was already present in the soil to meet the maximum plant requirements. To this and to similar oversights may be attributed some part of cer- tain of the discrepancies concerning especially the value of hoof meal and horn meal, although they may also have been due to the different methods of preparing the ma- terials used by the different experimenters; and to the occasional unrecognized adulteration with substances of highly inferior character. 213. Results by Eckenbrecher. — A study of the effi- ciency of certain organic substances was made by Ecken- brecher, for a single season, in “‘ sterile ”’ sand from which, based upon nitrate of soda at 100, he classified the effi- ciency of the nitrogen in certain substances as follows :— For THE PRopucTION | For THE PRODUCTION oF STRAW or GRAIN Gnoumeadlen) 6 rc ke Poe 100 Te Hornmeal. Si 62:2 91 56 Dried. blood)... os 86 65 Crude puano <2 . 6. . 6 6 It is evident that very different results might have been secured in normal soil. 214. Results by Kellner.-— It was found by Kellner, in the warm climate of certain parts of Japan, that organic nitrogen was superior to nitrogen in sulfate of ammonia, due, presumably, to the rapid nitrification of the former, and to its loss by drainage before the plants could utilize it. 215. Results by Petermann. — Many experiments on the availability of organic nitrogen were made by A. Peter- mann in Belgium from which he concluded that nitrate 116 FERTILIZERS of soda should be given the highest rank. This was fol- lowed in efficiency by dried blood, then by wool which had been treated with sulfuric acid, next by bone meal, then by untreated wool, and finally by leather meal. 216. Precautions suggested by Wagner and Dorsch. — Extended studies of availability by Wagner and Dorsch ! led them to lay down the following rules for such tests: (1) The experiments must cover several successive years. The same lots of soil must also be used throughout the whole period, and the same fertilization must be repeated annually. This is to aid in arriving at any cumulative effect of the organic fertilizers, in contrast to the supposed more temporary action of the nitrogen in nitrates. Con- cerning this recommendation, it may be said that its im- portance seems to have been somewhat overestimated in view of the many cases on record in which but relatively little effect is noticed, the second year, from heavy appli- cations of organic nitrogen; furthermore, the cumulative effect of nitrate of soda in an acid soil, due to its basic properties and to the possibility of its nitrogen being partly transformed into ‘‘ humous”’ combinations, may also be much greater than is sometimes recognized. (2) The soil must contain sufficient lime to insure that there will be neither delay nor cessation of the process of nitrification. (3) In selecting the soil, one should neither use one that is extremely favorable as concerns its physical character, nor one which is exceedingly poor, but rather a soil that would be ranked as medium in this respect. Later, if desired, the results may be studied under extreme con- ditions. 1Die Stickstoffdiingung der Landwirtschaftlichen Kulturpflanzen, Erster Theil, Berlin, 1892, pp. 242-258. THE AVAILABILITY OF ORGANIC NITROGEN 117 (4) One should introduce as many different organic ni- trogenous fertilizers into the experiment as possible, in order that the results with a given substance may appear in their proper relation to those secured with other substances. Fic. 8. — BARLEY, ‘‘ UNLIMED.”’ 1. No nitrogen. 2. Ammonium sulfate. 3. Leather. 4. Dried blood. 5. Nitrate of soda. Same amounts of pot- ash, phosphoric acid, and nitrogen used in each case. Same as Fig. 9, except for the omission of lime. (5) None of the fertilizers should be applied until spring, in order to avoid possible loss during the winter. (6) In case a substance contains some other fertilizer ingredients than nitrogen, care must be taken, by the addi- tion of an assured excess of all of them, to eliminate the possibility of their having influenced the result, 118 FERTILIZERS (7) All of the lots of soil must receive even slightly more of all the necessary fertilizers, other than nitrogen, than are necessary to the production of a maximum crop. (8) Less nitrogen should be used in all cases than is necessary to the production of a maximum crop, in order that the best’ forms may exert their full effect. (9) In order to make sure that the conditions under (7) and (8) have been surely met, nitrogen must be applied in at least two different amounts. Fic. 9.— BARtey, ‘‘ LIMED”’ (EXCEPT 1). 1. No nitrogen, no lime. 2. No nitrogen. 3. Ammonium sulfate. 4. Leather. 5. Dried blood. 6. Nitrate of soda. All received like amounts of potash, phosphoric acid, and nitrogen. Like Fig. 8, excepting that lime was used for all but No. 1. (10) The nitrogen content of the soil which is selected should be so low that fairly large applications of nitrogen may be made, for the accuracy of the results will be in- creased thereby. (11) One should use relatively larger amounts of the less available substances than of the more active ones, in order that the experimental error may be made as nearly alike in all cases as possible. (12) The experiments should be eonducted on land THE AVAILABILITY OF ORGANIC NITROGEN 119 in its natural condition, as well as in pots; since the former provides against any possible errors due to higher tem- peratures in the pots, and the use of the latter insures against losses by drainage. 217. Results of tests by Wagner and Dorsch. — The experiments by Wagner and Dorsch were conducted with due recognition of the foregoing precautions, including tests in pots and in soil in its natural location. These experimenters call attention to the variation in the chemical and physical character of such nitrogenous materials from time to time; also to the wide variations in soil temperature, moisture content, and other factors that may modify results. Finally, as representative average figures expressive of the efficiency of the nitrogen in various materials, based upon nitrate of soda at 100, they give the following : — RELATIVE VALUE Mimo im mitrate Of Oda: 66sec 100 Nitrogen in sulfate of ammonia . 90 Nitrogen in dried blood, horn meal, and green (not yet woody) plant substance . . 70 Nitrogen in fine ground bone meal, meat meal (azo- Mee eae Ory PYOUM HSI itis. nc. WY ore TR ns 60 Pate Se MANUIPe Ss S) ein ke 45 INT OMeiuIn WwOO)*WaSt@: j-sire 2.2.) Po achees este ey Ce 30 milirorer ii leather meal .7 G2) yo ae ee 20 218. Results by Wheeler and Hartwell. — In experi- ments by Wheeler and Hartwell made in “ Miami ”’ silt loam, in deep pots set in the ground so as to make the interior and exterior soil level, sulfate of ammonia was found to be highly toxic, if employed without lime, but when used with lime its efficiency rose to 92 on the basis of 100 for the nitrogen in nitrate of soda. Similarly, on the unlimed soil the efficiency of the nitrogen in dried blood was but 45.5 on the same basis, whereas after liming 120 FERTILIZERS it was 90.3. Steamed, ground leather had an efficiency on the unlimed soil of but 0.9; but after liming the eff- ciency rose to 13.8, or to essentially the same figure noted by Wagner in many of his individual experiments. 219. Results by Voorhees.—In a series of experi- ments by Voorhees at the New Jersey experiment station it was found that the nitrogen of nitrate of soda was more available than that in any other materials. It was also found, when nitrate of soda was employed, that the crop was able to secure even a larger proportion of the soluble nitrogen derived from the soil and from the manures which had been added to it, than when no nitrate was used. Placing the value of the nitrogen in nitrate of soda at 100, the following seasonal variations in the efficiency of the nitrogen in other substances were observed by Voorhees : the value of the sulfate of ammonia was 99.5 in the year 1898, 77.9 in 1899, and 87.8 in 1900. The corresponding values found for dried blood in the three years were, respec- tively, 95.4, 61.8, and 73.1. It was also shown by Voorhees that the soluble nitrogen in liquid manure possesses a high value. The insoluble nitrogen in fresh and leached barn-yard manures was found to become gradually soluble ; and its value was much greater as the length of the period of growth was in- creased. Views of Lawes. —In the climate of England, Lawes considered the nitrogen of shoddy and of most other or- ganic substances as being only from one-half to two-thirds as efficient as that in nitrate of soda, sulfate of ammonia, and guano. 220. Results by Kellner on wet soil.—It has been shown by Kellner that in the wet rice fields of Japan am- monia, instead of nitrates, is formed from organic nitrog- THE AVAILABILITY OF ORGANIC NITROGEN 121 enous substances. In his experiments with rice he used in one series twice as much nitrogen as in the other, and in both cases liberal quantities of phosphoric acid and potash. The applications were also made some days in advance of the setting of the rice plants in order to avoid toxic effects from a too rapid formation of ammonia at the outset. The natural soil, when air-dried, contained 0.61 per cent of nitrogen. Under such circumstances, in the warm climate which prevailed, the relative efficiency of the vari- ous materials, based upon the mean of the gain in crop, and of the nitrogen recovered, was found to be as follows : — RELATIVE EFFICIENCY No manure .. ee Me Pe Nati ars ge ATR CS le 0 Bele ainvemnatis}.7 ule ke MON OS oak, ee 100 Bone meal, steamed . Ae oe eee ars 142 Fish-scrap, 9.9 per cent of nitrogen Phe EE Re non 135 Fish-serap, 9.5 per cent of nitrogen . . ... . 133 18) Feraye | Sra) Soe ORR ae | SOME” Ae gic? haley mene ag eee ee 130 OMG AMIGE PAW, via J Sas price sat ala vache ere et Ga hen Si 120 Distillery slop, GEOG ES OF he os nok ee ee ee 118 Hformemeéal. =>". DR tate a ae eke hee wi pee igh ee eee 116 Peruvian guano C ht ad ee PA: Meee ote he ic 116 EEPORSRCAOM SES. Site) es Deel FRE GUO aay 104 FUEL CHICOI I 22 cada hye eau ce badl tel Rage ga la Peas abe 106 INCcMtRSOlloa ra oe | So Pee ee eTuecy MOR ape eta aad TEPLOE NY 106 AE eat COT ENFATIGS "9,5, Cale a ys ARR eT OA le Ace 88 ERICOPITTS eareters 6.0L. Seguin an aunt: teeme canes Ss ay Mate 48 GTESTIOOIATIES Sect 16 ren cnte. Seen trate ede SANs 42 Owing to the fact that irrigation waters were used on the lands where the foregoing tests were made, the mate- rials containing nitrogen which was wholly or partly sol- uble were at a great disadvantage, as compared with the materials from which the nitrogen could not be so readily dissolved and carried away. This applies particularly to the sulfate of ammonia, farm-yard manure, night soil, guano, and materials of similar character. It is obvious, therefore, that the figures in the preceding table are ap- 139 FERTILIZERS plicable only to similar conditions and not to those po gn! existent on farm lands. 221. Results by Seyffert.— In experiments by Seyf- fert with kohl-rabi, in which identical amounts of nitrogen were used in all cases, in the various materials, the fol- lowing results were secured : — GRAMS OF CROP No nitrerenous foriilizer 24. 2.0% -s Lee 76 Crude Miejilones cuano rages. as eee eee tate nes 7 eatherimeal, steamed: ves. .)wests cae nes eae 469 Sfeamed bonesImealle 4:7 lel ce. spin aete et coe Be camera 1572 Dried blood . . Sah seythe stlay “esp irgen Wad Galt sae ARC a, SPs 1654 Horn meal, steamed Wes giles) aie ae aes Ber ee tee moat omar? 2005 Nitrate of soda BC tit ican Wether gh eae a 2608 222. Results by Heinrich. — Experiments are on record by Heinrich in which he found, with oats, that there was no material difference in the efficiency of the nitrogen in leather meal and in blood meal. This result is, however, so completely out of accord with the experience of other experimenters that serious doubt is cast upon the genuine- ness of the blood meal, or upon the suitableness of the con- ditions under which the experiment was conducted, or possibly upon the interpretation of the experimental data. 223. Results by Johnson. — According to 8. W. John- son’s experiments with Indian corn, certain organic nitrog- enous fertilizers should be rated in efficiency as follows : — Nitrate of soda BE ee ay. ose D0) Castor pomace (best results) . Weis Bae mre Fie sy), Linseed meal . . : eS e eh tS Beets) IDriedsblood | «Pees als) eke eis fare ree idl Cotton-seed meal. . be ead Pee LO Castor pomace (poorest results) . ae Meee een rare! Hoofiand horn areal. air er eee ee 72 Driedetisi ns io ea a ode eee canal) Manila grok. Fie te ote rene eee eee Seen uae THE AVAILABILITY OF ORGANIC NITROGEN 1238 224. Results by the nitrification method of Miintz and Girard. — Experiments were made by A. Miintz and Girard to determine the relative value of nitrogenous fertilizers by subjecting them to nitrification and measur- ing the amount of nitrates produced at the end of 30 and 39 days. This resulted in showing that the nitrogen in sulfate of ammonia should be ranked ahead of that in organic compounds. This was followed in order by the nitrogen of guano, bat manure, leguminous plants used as green manure, dried blood, meat meal, horn meal, and roasted horn. Roasted leather was found to nitrify very slowly, and raw leather not to any practical extent. 225. The pepsin method. — Many investigators in the United States and in Europe have studied the solvent action of pepsin solution upon various organic nitrogenous substances as a means of determining their crop-producing value. The results in many cases accord fairly well with those secured in tests with plants, though certain gross disagreements have been noted. It was found in the course of this work that a preliminary treatment of the material with borax increased the solvent action of the pepsin. 226. The permanganate method.— In the hope of finding some ,more reliable chemical method than that afforded by treatment with pepsin, many experiments with potassium permanganate have been made in acid, neutral, and alkaline solutions. Recently the agricultural experi- ment stations of New England, New York, and New Jersey have adopted, tentatively, the treatment with an alkaline solution of potassium permanganate, for the pur- pose of furnishing evidence as to the probable efficiency of the insoluble organic nitrogen in ready-mixed commercial fertilizers. The organic residues, remaining after extract- 124 FERTILIZERS ing the fertilizers with water, are being tested, by way of pot experiments with plants, in order to ascertain how far this chemical method of treatment is in accord with the degree of availability shown by plants in normal soil. 227. Lipman’s ammonification method. — Recently Lipman ! and others have suggested the determination of the availability of organic nitrogen by the rate at which ammonification occurs, under definite conditions. P—O—Ca—O- PK Ca), though it also contains very small quantities of magnesia and fluorin. In the case of bones which are not care- - NATURAL PHOSPHATIC FERTILIZERS 167 fully prepared, traces of fluorin, sodium, and iron are fre- quently found which are present in slight residues of blood. The organic matter of the bone includes ossein, col- lagen, and chondro-mucoid. The ossein when dry contains about 17 per cent of nitrogen and may be converted by long heating with water into glue and gelatine. The following statement by Murray shows quite fully the constituents and average percentage composition of the fresh bones of mammals : — Per CENT Water ak en age ig 6.7 ; fat 14.6 Organic matter . 40.0 | ossein 25.4 = 4.0 nitrogen P.O; 22.3 = 48.7 Ca3(PO,)2 PMY 2 Son) 6 si. te Does OBO 29.2 Mg. F, ete. 1.8 100.0 100.0 296. Composition of the ash. — When bones are burned, only the mineral matter remains behind, and this is known as bone ash. If bones, on the other hand, are treated for a long time with dilute hydrochloric acid, the mineral matter is dissolved and the organic framework of the bone remains, still possessing its original form. 297. Composition of weathered bones. —In the case of bones which have been burned for a time, or which have lain exposed to the weather, considerable of the organic matter has been lost, and they are therefore poor in nitro- gen, but richer in phosphate than fresh bone. 298. Treatment of bone for the removal of fat. — The treatment of bones for the removal of fat may consist in boiling, steaming at high pressure, or extraction with naphtha or other solvents. The fat is in such demand and has such a high commercial value that it is now 168 FERTILIZERS usually removed from bones, more or less completely, be- fore they are marketed for fertilizer purposes. The bones are ground and sold as fine or coarse ground bone, accord- ing to the degree of fineness. Such bone usually contains from 1.5 to 4 per cent of nitrogen. After the extraction of the fat by means of a solvent, or by boiling in water, bones are sometimes subjected to high steam pressure for the removal of gelatine. In some cases, also, the bone is treated directly with steam at high pres- sure, which removes most of the fat and much of the ossein in a single operation. After bones have been steamed in this manner, they crumble readily and can be ground with ease to a fine powder. The material is sold in this country under the name of “ fine-ground steamed bone,” although the designation “ steamed ”’ is often omitted. 299. Effect of steaming on the nitrogen content. — Bone, if subjected to severe steaming, may not contain more than from 1 to 1.5 per cent of nitrogen instead of from 2 to 4 per cent, as would otherwise be the case. On account of the removal of so much of the organic matter in such cases, the content of-phosphoric acid may rise to from 27 to 30 per cent, which is from 5 to 6 per cent above the amount usually found in commercial bone. 300. Bone wastes from industries. — Bone is used for the manufacture of buttons, knife handles, and a vast number of other articles; the wastes from which are ground and sold as bone meal or are used in compound- ing commercial fertilizers. When bone is subjected to destructive distillation, animal charcoal, containing about 10 per cent of carbon, is pro- duced, in a manner analogous to the production of wood charcoal from wood. This material is employed in sugar NATURAL PHOSPHATIC FERTILIZERS 169 refineries for clarifying sugar solutions, and when no longer fit for such use it is either reduced to bone ash, or it is treated with sulfuric acid. By the latter process the bone- black is transformed into a superphosphate known com- mercially as ‘‘ vitriolated”’ or “ dissolved’ bone-black. Bone is sometimes used in the process of annealing, as a result of which it loses much of its nitrogen and becomes highly carbonized, consequently closely resembling bone- black. Such material, though occasionally sold for use directly as a fertilizer, should preferably be treated with sulfuric acid before its application to the soil. 301. Fermentation and other methods of disintegrating bone. — In England and elsewhere bones are sometimes moistened with water and allowed to ferment in heaps, which process renders them more available.: Bones have also been treated in tanks with urine from cow stables which causes them to gradually soften and disintegrate. The process of steaming increases greatly the solubility of bone in ammonium citrate, and it is usually conceded to greatly increase the availability of the phosphoric acid to plants, though it has been found by Kellner, in Japan, in a moist and hot climate, that bone before steaming was even more available than afterwards. 302. Bone meal as a fertilizer. — The most ideal soils on which to use “ undissolved’? bone meal, whether steamed or raw, are those which are open and inclined to be sandy or gravelly, though they should not be too dry. On the other hand, bone acts more slowly on heavy clay and silt soils. For many years bone meal was the favorite fertilizer of the American farmer, not only on account of its well- known power to immediately increase crops to a consider- 170 FERTILIZERS able extent, but chiefly because of its accredited lasting qualities. (See Fig. 14.) In recent years the use of acid phosphate and of other superphosphates has increased to such an extent as to keep bone down to a price which still admits of its frequent agricultural use. At the same time, on account of the greater demand for vegetables and for early garden. crops, which must reach a marketable stage in the shortest possible time, many farmers have come to a realization of the fact that it is often better cconomy to expend money - for quick-acting acid phosphate rather than to tie up in the soil, for some years, a large investment in bone. Bone meal is a favorite substance for application before seeding land to clover and grass. It is also much used for fruits, hops, and for crops which require a long season in which to mature. If bone meal is applied continually for many years to a soil in need of liming, it very gradually tends to correct the condition; but not rapidly enough to justify waiting for it todothis work. In fact, basic slag meal is far more efficient in this direction than bone meal, and it is at the same time a more quickly available phosphate. For plants and soils which need liming, it is always more economical to lime the land at the outset, no matter what the form of phosphate to be used, than to wait for the phosphate to gradually correct the exist- ing conditions. 303. The soluble and reverted phosphoric acid of bone. — Ground raw bone and steamed bone rarely yield much more than 0.5 per cent of ‘soluble’ phosphoric acid upon long and thorough leaching with distilled water, and raw bone is but slightly soluble in neutral ammo- nium citrate solution, at the usual temperature of 65°C, Dk NATURAL PHOSPHATIC FERTILIZERS ‘dU0g pautnajs Puno . Teas ‘ES-GT ‘SSI UI Se prloe olmoydsoyd jo yunowre suIRg iB auy JO syooHe Joyye SurmMOYG oa1B'T PemarTe hy "BpOSs JO 0}¥I}TU pue YsezOd jo 97vLMUI YIIM poztiIyJoy YO ‘SHOLVLOG GANWIINQ) GNV GaWIT — ‘FT ‘DIT leg osie'T peury 172 FERTILIZERS at which ‘‘ reverted’ phosphoric acid is determined. Steamed bone, on the contrary, yields a considerable per- centage of reverted phosphoric acid, which, added to the soluble, makes up the “ available’ phosphoric acid re- ported by analysts. It is probable that the reverted or available phosphoric acid of bone is nevertheless not so readily utilizable by plants as “ back-gone,” or true re- verted phosphoric acid (dicalicum phosphate), which is produced by the direct action of lime or of tricalcium phos- phate upon soluble phosphoric acid (monocalcium phos- phate). 304. Bone tankage. — Bone tankage contains widely varying percentages of phosphoric acid and _ nitrogen, ranging from 9 to 20 per cent of the former and usually from 4 to 8 per cent of the latter. What has been said of steamed bone applies to the tank- age produced by subjecting the waste bones of slaughter- houses and meat markets to the action of superheated steam. It is not infrequently the éase that as much as one-half of the total phosphoric acid of such tankage is rendered soluble upon treatment in the conventional manner with neutral ammonium citrate solutions at 65° C., and it hence appears in the statement of the analysis as reverted phosphoric acid. What has been said of the use of bone in the previous section applies equally to the prac- tical employment of tankage. 305. Fish as a source of phosphoric acid. — The refuse fish from the menhaden oil factories often contain, in addition to the 6 to 8 per cent of nitrogen, from 5 to 7 per cent of phosphoric acid. Fish heads and skeletons from fish works are often still richer in phosphate. Such fish wastes are often dried, ground, and sold directly to farm- ers; they are also introduced into commercial fertilizers, NATURAL PHOSPHATIC FERTILIZERS Lie especially in the manufacture of the goods sold under the name of “fish and potash.” 306. The nature of floats. — The name “floats” was given originally to an especially fine dust product which was formed in connection with the ordinary grinding of phosphate rock, but it is now often applied to any finely ground, unacidulated tricalcium rock phosphate. 307. Soils on which to use floats. — This phosphate is especially applicable on peat or muck soils, as has been abundantly demonstrated in the course of the experiments on the renovation of the acid peat (Hochmoor) soils of northern Germany. Next to peat and muck soils, this material is useful on such upland soils as are exceptionally rich in acid vegetable matter. The profitable use of such phosphates has been especially pointed out by Hopkins in his work with the black soils of the Illinois corn belt. This phosphate is much less applicable on light, open, sandy, and gravelly soils than on those previously mentioned. 308. The action of manure on floats. — According to pot experiments by Hartwell and Pember! and to ex- periments by The. Rémy,? the mixing of the raw trical- cium phosphate with stable manure and decomposing materials does not materially increase its efficiency. In fact, the field experiments at the Ohio station which have been frequently cited elsewhere to prove the contrary were not conducted in such a manner as to furnish posi- tive evidence on this point either pro or con. It still remains to be conclusively demonstrated that floats are rendered more effective by being introduced either into the manure directly or by scattering them in the gutters behind the farm animals. 1 Bulletin 151, R. I. Station. 2?Bonn. Landw. Jahrb., 40, 559-611; Abs. Chem. Abstracts, 6, 1048. 174 FERTILIZERS 309. How floats should be used. — It is true of floats, as of other rather insoluble phosphates, that the best way to apply them is to incorporate them thoroughly with the soil; for their availability is affected not only by the car- bonic acid brought into the soil by the rain and produced therein by the decay of vegetable matter, and by contact with acidic matter in the soil, but also by the nitric acid resulting from active nitrification. Floats are obviously most applicable to those aaa which have a long season of growth, and least of all for such garden or trucking plants as must be pushed rapidly to maturity. In the latter case the crops must not only reach the market at the earliest possible moment, but the growth must be rapid in order that they may be tender and acceptable to the consumer. Again, floats are less ap- plicable for those plants which possess a low feeding power for phosphoric acid, such as the turnip, cabbage, and certain other similar plants, than for crops possessing a greater feeding power, as, for example, Indian corn, millet, clover, and certain grasses. Indeed, this difference in the requirement for readily available- phosphoric acid has been well established by field experiments at Rotham- sted, by many European experimenters, and by Brooks and others in the United States.!. Nevertheless, it is claimed that certain of the cruciferous plants can utilize raw phosphates better than either the oat or vetch can utilize them.’ 310. Liming in connection with the use of floats. — The advice is often given never to lime land to which floats are to be applied on the ground that the lime, if freshly burned or hydrated, will absorb carbonic acid 1 See Buls. 114 and 118 Agr. Expt. Sta. of the R. I. State College. 2 Centralb. f, Agrikulturchemie, 39 (1910), 495. NATURAL PHOSPHATIC FERTILIZERS 175 which might otherwise serve to attack the floats and render them more available. Another reason often given is based upon the known greater solubility of calcium carbonate than of tricaletum phosphate in carbonic acid. On this account the carbonic acid would be expected to be utilized in dissolving calcium carbonate, before it would attack the tricalcium phosphate to an appreciable ex- tent. Admitting that this might be sound advice as concerns a soil already well supplied, naturally or artifi- cially, with reasonable amounts of calcium carbonate, it does not, nevertheless, apply in all cases on such soils as are naturally deficient in calcium carbonate, especially if they are of a quite acid character. In order to make this point plain, it should be stated that a soil may be so acid that given varieties of plants will not thrive well upon it, and hence no matter how much phosphoric acid is made available by the action of carbonic acid, nitric acid, or otherwise, the plants cannot utilize it, because another factor has become the one which limits growth. Under such circumstances, therefore, enough lime must be applied to make the soil a suitable habitat for the plant, even though upon theoretical grounds, and with- out reference to the plant to be grown, the omission of lime would seem to be advisable. If, on the contrary, plants are grown which, like golden millet, serradella, and certain lupines, thrive well.on acid soils, the advice about avoiding the use of lime, even on moderately acid soils, might nevertheless be sound. (See Fig. 15.) 311. Apatite or phosphorite. — The terms “apatite” and “‘ phosphorite’? have come to be used interchangeably, although the latter is the term preferred for commercial purposes. Distribution in soils. — Apatite is a phosphate which is FERTILIZERS 176 JO JUNOWIB 9UIBG eug "€S-9L PUe FT ‘SBLT Ul se plow oLoYdsoyd ‘sqpoyf JO yOaye Joyye SUIMOY “wBpos jo 97e1}TU pu Yyseyod Jo oyeLINU YY pozi[iqJoy YO ‘SHOLVLOG GHWIIN() GNV GAWIT — ‘CT “SI osIe'T emus as1e'T peurya) ee NATURAL PHOSPHATIC FERTILIZERS a G7) widely distributed in minute crystals in most soils, and especially in rocks of igneous origin. This phosphate has probably been the source of the phosphorus in the organic matter, and in other combinations, in most soils of such derivation. It has been assumed that in many cases minute crystals of apatite are formed in the soil under normally existing conditions, although laboratory experiments made in the attempt to produce them, in a wet way, have thus far failed. 312. The chemical composition and occurrence of apatite. — The pure crystals of apatite are usually blue or green, although they may be gray, white, and transparent. The mineral, if pure, is a fluor-apatite correspondjng closely to the formula 3 Ca3P,03 + CaF». Occasionally, however, the fluorin is wholly or partially replaced by chlorin, in which case the apatites are lighter in color and are designated as chlor-apatites. The pure fluor-apatite contains about the equivalent of 92.25 per cent of tricalcium phosphate, and 7.75 per cent of calcium fluorid. A sample of Norwegian apatite examined by Voelcker was found to have the following composition :— Per CrentT Tricalcium phosphate. . . .-. . 90.07 Calenim: chloridisisiw ee ee eee ee 6.13 CWaleurin HUOTIGN MAS 2s4Le. | Fee ue oe ke 2.54 Oxid. Gr iron ten 7 eietos es Smee 0.29 Alumina . APEET oh koe ee 0.38 Potash and soda eRe it eet NT ie n't 0.17 NViGOrs 2 ty: ees fe Pe bee a 0.42 Apatites are found in several places in Renfrew and Lawrence counties in Canada, where beautiful large crystals occur, likewise in the Province of Estramadura, Spain. They also occur in Portugal, Norway (near Chris- tiania), and elsewhere. Apatite is often found in veins N 178 FERTILIZERS mixed with quartz, as nodules in certain sand-stones, in carboniferous slates, and as cementing material in rocks. Many of the apatites occur in massive or amorphous forms. For several years the apatites of Canada, containing the equivalent of 80 to 86 per cent of tricalcium phos- phate, those from Norway, containing the equivalent. of 70 to 90 per cent of tricalcium phosphate, and the deposits in Spain, containing the equivalent of from 70 to 85 per cent of tricalcium phosphate, were worked quite extensively ; but these phosphates have since been largely replaced by those from Algeria, Florida, Tennessee, and from many other sources. At present renewed interest in them is being awakened in view of their possible utilization by the process of Palmaer (see Section 340). When apatite is reduced to a powder and is subjected to the action of pure water, the resulting solution gives an alkaline reaction with phenolphthalein or litmus, whereas the ordinary tricalcium phosphates yield an acid solution with the same indicators. . The solubility of apatite is about seven times as great in a saturated solu- tion of carbon dioxid as in water, but even then more lime than phosphoric acid is dissolved. The presence of even a small amount of carbonic acid in solution also increases its solubility. 313. Wagnerite. — The mineral Wagnerite is a mag- nesium fluor-apatite corresponding to the calcium fluor- apatite. There exists also a corresponding ferrous salt known as triplite, but neither of these is of importance as a soil mineral or from the fertilizer standpoint. 314. Coprolites.— The term “ coprolite”’ from two Greek words meaning ‘‘ dung” and ‘ stone’”’ was given by Buckland to certain peculiarly shaped stones found in the Lias marls chiefly at Lyme-Regis and also near Bristol, NATURAL PHOSPHATIC FERTILIZERS 179 England, which were said to resemble fossil fir cones. They are from 2.5 to 4 or even in extreme cases 8 inches in length, somewhat flattened, and ranging in color from ash gray to black. The coprolites were found in deposits with remains of the Jchthyosaurus and the bones and teeth of fish, which coupled with the fact that their struc- ture resembled that of fossilized animal excreta, led to the belief that they were chiefly the excreta of reptiles of the extinct group of saurians. The term “coprolites” was, however, also applied to phosphates which are now known to be of undisputed concretionary character. The latter have also been called pseudo-coprolites in order to dis- tinguish them from those of fecal origin. Coprolites are by no means confined to England, for they occur in France, Russia, and elsewhere. The concretionary origin is supposed to be the result of the replacement of the carbon dioxid of calcium car- bonate by phosphoric acid, in the presence of moisture and vegetable matter. The coprolites are usually associated with considerable calcium carbonate, also with calcium fluorid, oxids of iron, alumina, silica, and small amounts of organic matter. They usually contain from 50 to 60 per cent of tricalcium phosphate. 315. Phosphatic guanos. — Where birds deposit large quantities of excreta in humid locations the material gradually loses its nitrogen until the residues finally be- come mineral phosphates. The Island of Lobos yields a guano with only from 2 to 3 per cent of nitrogen. This represents a stage between the true guano with a high nitrogen content and these true phosphatic guanos. These phosphates often con- tain, as might be expected, traces of nitrogen and alkalies, 180 FERTILIZERS but the amounts are too small to be of any practical account. Such guanos often contain from 70 to 80 per cent of tricalcium phosphate and usually but small quantities of iron and aluminum. These characteristics, and the ease with which they can be pulverized, make them well adapted to the manufacture of superphosphate. The phosphatic guanos known as Aruba, Navassa, Sombrero, and Curacao are found in the West Indies. The Mejillones guano comes from Bolivia, and large quan- tities have been found on the Baker, Abrolhos, Christmas and Oceanic islands in the Pacific, and elsewhere. Some of these guanos have an average content of 80 to 85 per cent of tricalcium phosphate. Many of the original deposits have been exhausted, but the phosphate is still being imported from the Oceanic and Christmas islands, and from a large number of other islands of the Pacific. Clipperton Island in the open sea off the coast of Brazil is covered with a bed of phosphatic guano six feet deep. It contains from 83 to 86 per cent of tricalcium phosphate and only traces of iron and alumina. 316. Nassau or Lahn phosphate.— The so-called Nassau or Lahn phosphate is found in Germany and these deposits were worked extensively following their discovery in 1864. They contain from 35 to 70 per cent of tricalcium phosphate; but such large amounts of iron and alumina are present as to make them objectionable for the manufacture of superphosphate. Germany has at present practically no workable phosphate deposits. 317. French, Belgian, and Portuguese phosphates. — The Departments of Pas de Calais, Somme, and Oise, in France, contain valuable deposits belonging to the Cre- taceous period; and many other sections of the country NATURAL PHOSPHATIC FERTILIZERS 181 also contain very extensive deposits, though often in thin beds. Phosphate deposits at Mesvin and at Cipley near Mons, Belgium, have been worked extensively. The lower grades from these deposits contain from 25 to 30 per cent of tricalcium phosphate. The better grades, which occur chiefly in pockets, contain from 45 to 60 per cent of tri- calcium phosphate. This phosphate is light brown and has practically the appearance of odlite. It crumbles easily and owing to its peculiar structure it has at times been imported into the United States in small amounts for use as a drier in mixed fertilizers, in order to make them more drillable. Other phosphate deposits exist in the district of Liége and elsewhere in Belgium. . Phosphates somewhat similar to those of Cipley have been found in France, Portugal, and elsewhere and, al- though they are often quite rich in tricalcium phosphate, they contain clay and marl in quantities objectionable from the standpoint of the superphosphate manufacturer. An exception is however afforded by the Somme phos- phates of northern France which are richer in tricalcium phosphate, and contain less iron and aluminum oxids. In utilizing them for the manufacture of superphosphate it is considered desirable or necessary to employ hot rather than cold sulfuric acid. 318. The phosphates of Russia and Northern Africa. — In Russia there are large numbers of phosphate deposits, the best of which are in central Russia. They are dis- tributed over an area estimated at 50,000,000 acres. One of the chief sources of phosphate for Europe, at present, is the great deposit supposed to stretch practically across the northern part of the continent of Africa, though 182 FERTILIZERS Morocco has not as yet been carefully examined. The centers of export are Algeria and Tunis from which ap- proximately two millions of tons are now shipped annually. The amount of tricalcium phosphate usually present in the material as exported is about 60 per cent, but by careful selection it may run as high as 70 per cent. The beds thus far explored in Egypt yield a phosphate containing only from 40 to 50 per cent of tricalcium phos- phate, which is too low for present profitable exportation. These deposits underlie the Eocene; and the phosphate- bearing strata usually range from 7 to 10 feet in depth. One great advantage of these phosphates is that they contain only little iron and alumina. When used in an unacidulated form in comparison with the Florida phos- phate, on the Hochmoor (acid peat) soils of northern Germany, they have been reported as being superior to the American product. 319. The phosphates of South Carolina. — Until within the last twenty years the main source of phosphate for the United States was South Carolina. The chief supply for Europe came also from the same source until the dis- covery of the high grade African deposits. Many of these phosphates are essentially nodular and belong at the bottom of the Eocene period; others consist of phos- phatic limestones alternating with the nodular deposits. The material resembles somewhat that at Cipley in Bel- gium. Associated with the phosphates, in the beds of marl, are teeth and bones of sharks. The phosphate, however, has been redeposited from solution in carbonic acid and in organic acids, and is still being formed. The so-called “ river ”’ phosphate was secured by dredg- ing the bottoms of rivers, whereas the usual methods of mining prevail in connection with the land phosphates. NATURAL PHOSPHATIC FERTILIZERS 183 The former contain usually about 60 per cent of trical- cium phosphate, but they are preferable for the manufac- ture of superphosphate to the richer (70 to 80 per cent) land phosphate on account of their containing less iron and aluminum oxids. 320. The Florida phosphates.— The discovery of phosphates of the Oligocene period in Florida in 1887, followed by their extensive exploitation, focused the attention of the entire world upon them. The black, river, pebble phosphate containing 60 to 70 per cent of tricalcium phosphate was formerly dredged in large quantities from beds of streams, but such mining in the Peace River district has now been abandoned. The land pebble phosphate, which bears much resem- blance to calc-sinter, is found in Florida in large quantities ; and the output has reached as much as 1,250,000 tons per annum. It is consumed chiefly in the United States. It contains from 66 to 75 per cent of tricalcium phosphate and an average of 2.3 per cent of iron and aluminum oxids, though the latter usually fall below 2 per cent. The masses are rounded, flattened and of a yellowish to white color and occur associated with occasional stringers of quartz sand. The deposits resemble gravel beds in cer- tain respects. The better grades of land phosphate, to which the terms “rock” and ‘‘bowlder ”’ phosphate are applied, vary less in composition than the pebble phosphates and are sold on a guaranty of 77 per cent of tricalcium phosphate, but they not infrequently contain as much as 80 per cent. This is much in excess of the amount in the South Carolina phosphate. They frequently, however, contain as much as 6 per cent of iron and aluminum oxids which is a highly objectionable feature. 184 FERTILIZERS Soft phosphate. — The Florida ‘ soft ’’ phosphate, con- taining from 25 to 70 per cent of tricalcium phosphate and 3 to 7 per cent of iron oxid and alumina, is usually associated with such large quantities of calcium carbonate or earthy matter, as to render it unsuitable for the most economical manufacture of superphosphate. For this reason it has been ground and utilized to a considerable extent for direct application to the land, and likewise as a drier in the manufacture of commercial fertilizers. 321. The Tennessee phosphates.— Upon the dis- covery of the great phosphate deposits of Tennessee in 1894, following closely upon those in Florida, it was con- sidered that inexhaustible supplies were at hand; the quantity mined has, however, reached from two to three million tons per annum and it is now estimated by the U.S. Geological Survey that the exhaustion of these deposits will be accomplished in another generation, if the mining increases at as great a rate as is to be expected. 322. Phosphates of the Western States. —In view of the rapid exhaustion of the phosphate beds of the eastern United States, the recent discovery of high grade phos- phate fields in Idaho, Wyoming, and Montana, which are now believed to be the greatest thus far discovered in the world, is hailed with great satisfaction by those in- terested in the future prosperity of the United States. In each of the nine townships thus far examined it is estimated that there are not less than 60,000,000 tons of high grade phosphate rock, and in one of the townships the estimate reaches 293,000,000 tons. The preceding estimates do not embrace 34,000 acres of Montana phosphate beds previously withdrawn from the lands opened for settlement. These figures are es- pecially significant when one recalls that but about 39,000- NATURAL PHOSPHATIC FERTILIZERS 185 000 tons of phosphate rock have thus far been mined in the United States. Certain of these western deposits are situated reason- ably near great copper smelters which are capable of pro- ducing enormous quantities of sulfuric acid as a cheap by- product, so that the conditions are especially favorable for the manufacture of acid phosphate or of other even richer products. In the case of some of the latter the cost of transportation, per unit of phosphoric acid, would be but one-third of the cost in ordinary acid phosphate. 323. Occurrence and composition of certain aluminum phosphates. — Aluminum phosphate, associated with some iron phosphate, is found on the Islands of Grand Conne- table, a French possession on the coast of French Guiana ; on the Island of Redonda (where the mineral redondite occurs), near the Island of Montserrat in the British West Indies; and on the Islands of Alta Vela, Sombrero, and Navassa. The material from the Island of Redonda often contains as much as 35 to 36 per cent of phosphoric acid, combined almost wholly with alumina. It may never- theless contain in some cases as little as 20 per cent of phosphoric acid. The phosphates from Alta Vela, Som- brero and Navassa, contain about 22, 31, and 31 per cent of phosphoric acid, respectively. Wavellite. —The mineral Wavellite is a crystallized aluminum phosphate (3 Al,O;-2 P.:O;-12 HO) which, though possibly formed in a wet way, is supposed by certain writers not to be generally present in soils. 324. Roasting increases the efficiency of aluminum phosphate. — The efficiency of these phosphates is greatly increased by subjecting them to a roasting process. This fact is not new but it has been recently well shown in trials of the roasted and unroasted product, at the experi- 186 FERTILIZERS ment station of the Rhode Island State College, and later in the course of experiments by Fraps. The Rhode Is- land experiments have shown in a most striking manner the effect of slaked lime in increasing the crop-producing efficiency of the roasted, in contrast with the unroasted, Redonda phosphate. Furthermore, this effect con- tinues for several years after the last application of each substance is made to the soil. (See Figs. 16 and 17.) 325. The solubility of artificial aluminum phosphate. — The solubility of artificial aluminum phosphate appears, according to Gerlach, not to be increased by the presence of carbon dioxid in solution, even in the presence of lime and magnesia, but its solubility is greatly increased by sodium and potassium hydroxids and in a lesser degree by free mineral acids. As concerns oxalic and citric acids, they differ but little in their solvent action upon the phos- phorie acid of aluminum phosphate, and both are far superior in this respect to acetic acid. The presence of aluminum hydroxid while lessening the solvent action of acetic acid had no effect upon the action of citric and oxalic acids. P According to Schneider? both aluminum chlorid and aluminum sulfate, which give acid solutions, increase the solubility of aluminum phosphate. The action of water upon several artificial preparations of aluminum phosphate of varying degrees of basicity, has been determined by Cameron and Hurst,’ from which it appears that the total quantity of phosphoric acid dis- solved, increased with the volume of water; but that the concentration of the solution became less as the quantity 1 Bulletins Nos. 114 and 118. 2 Zeit. anorg. Chemie., 5 (1894), 87. 3 Jour. Am. Chem. Soc., 26 (1904), 385. 187 FERTILIZERS ’ G NATURAL PHOSPHATI *EZ-ST pu® OI-FI ‘Sel UI Se plow o1oydsoyd jo yunoue auIeg ‘aynydsoyd wnurun)D puDd UOLL ,, PIJSDOL ,, IO ,, pazvubr,, JO JOoYo Joyye SUIMOYG “BpoOs Jo 9}¥1}TU pu Ysezod jo o}BLIMNUT YIM poZi[IyJof GOT “ae ‘SHOLVLOG GHNIING) GNV GHWT — "YT “DLT ems anIv'T yeug aes1B'T pemyay peu] “EZ-LI PUB GI-FT ‘SSL UI Se plow ooYydsoyd jo yunowe ouvg ‘aynydsoyd WNUVUNID PUD ULL MDL JO JOa + Be | ES lo Beles O~| SB | ag| & ® | NOILOATIOD 40 ES Bolte ee. ste ah HINO] SS aed a oes 8 NIVINOO daaim-Vag AUq JO SaGNNOg COT . . . . . -puno1 * pooaM-YOOI poy[ezs “unsopou (snany) wnppiydoosy * YSI[Ip ‘esynp ;‘pyouyod vruauhipoyay afsuey ‘uoIde-s [Aap ‘djey poyva]-peo1q ‘peaM-uoqqIr peroiq ‘njopbyp DiupUun'T . oe . . . . . . . . . a[suey ‘djoy ‘paeM-uoqqil ‘nUuLpYyIIDS DLLDULULD'T qaqa M-Vag (‘19}8M Jo yuIOd Burpiog ay} “OH .OOT JO o1njzesodui9} B ye poT[edxe AToaIQUe weeq pey J0}8M 9} YOIYM WOoIy asoy} ‘a°2 ‘spoaM-vos Arp AJEyNJOSGB Jo Wor}ISOdu09 ay} JUesetdor SosATBUB OSoY L) S€HUM-VAG NIVLUAD AO SASATVNY AO NOLLVTIdWO/) 231 POTASSIC FERTILIZERS “Iaquie}deg Ul porndes 9s0Y} OF IOquING sso[ 'B puB ‘Tore puv Arenuve ur uoye} sopdures oy} 0} poroypr s[[oys [wus Jo Joquanu oB1ey] V _ gl de 3 ga as aS | ast Aaa Fc le: Ve a uss10g “ATM "BYG “dxq 99819 ‘ssepy "BIg “dxq 09%9g ‘ssey SUBIQIA ‘O 2 Bee i Hees oe aoe a 2 gts Ee Wes be ar el aie 8 ps Mah Uae S Oe NST eel & SED TG. SAN SIC SE “BIg “dxq 07%4g “uu0,) IOUIUIBYYI.10 JF ey See Tee PAW eS ‘H "I'd PM ‘Cf 'H ‘HT 'd ¥'M ‘CH os ad Ge: Oe, ee ee be 2 Dead Dig a Meer Oi Goa ada 2b pueyoieyy “sng "BIg ‘dxq o7e4g ‘uU0D pueyssieg “yO SUBIqIA "O uoslepuy TOMB YYII0 7 sommes suayqoapor SOM EE a 2M ‘fH asl ey "B49 ‘dxq o}¥I1g ‘uU0D suryuor uoslepuy susqoepey Bet oL IGG 9T Lv 86° €F't SVT PLS Sol FES LET 6F'T LET Jour VES £0°S I0'T LYV'T 88° OFS GEE 19°€ L8°G I8TT IvG LVS EGE GOS SPT LOG 60'T 89'S 66°8 0G'6T IZ°ST GGG SLT Gh'G PLL PGT CTT L0°G 98'T F3'T FOS L9°T PLT LL T 6Z'T 98'T os’s vr TI PIT 8a 96°G Lee LVG 62'S L£9° COP GGG Lo°€ 69°€ L9°€ Il¢ o9'E 08'S 86'S co Svs OFT GET 19'S $9'% GG Pls LLG SOG Go's OL s LLé OFT 69'T 08's 8a T 8a T €l'T 8LG ELT 29°T GO'F GET Ole PSG isis 8L°G 6P'E GGT 90°€ 60°T 60°T cs" €6'T £0°S 90°E SLT roequreydag JTaqureydag qequreydag Yole yyy Arenue * Arenue yore yyy Taqutezydag Yole yy Arenue p Jaquieydeg ole yy Avenue ole yy Jaqueydag Yoel Arenue ore * pyooyd vupasuyy * snpunjo. sapiijog . . . . . . . > YORIM-S8B1F ‘SSBIS-[90 ‘DULLDUL D12]807 : * * snynypaysaa snydajsopn7,) . . . . . . . . . SSOUL WsodBIIVD IO YSU] ‘sndswo snupuoyy) 1 DYyOfiuniquau DLoydop hy J . . . . . . . . . . . -yooI poxyyeys-jey poom ‘snsopnoisaa = snony 232 FERTILIZERS and certain groups of American fertilizer manufacturers. It has, in consequence, been again proposed to make use of the enormous masses of sea-weeds available on the Pacific coast. This is no new idea, for sea-weeds have been thus utilized in the past, and even certain salworts (Salsola) have been expressly cultivated, collected, and burned in Spain, Sicily, and elsewhere, and the fused ashes sold under the trade name of “ barilla.’”? Ashes of these plants from near the Caspian Sea are said to contain 5 per cent of potash which is readily soluble in water. In earlier times straw and weeds of various. kinds were used for the manufacture of both sodium and potassium carbonates. At various times it has been proposed to utilize for this purpose wormwood, tansy, the common | marigold, and other plants rich in alkalies. 381. Analyses of sea-weeds.— Many analyses of sea-weeds common on the New England coast have been made by Wheeler and Hartwell,! and these, with analyses by others, are given in the tables on pages 230 and 231. 382. Tobacco stems. — Tobacco stalks and the waste midribs from the leaves are often sold as “‘ tobacco stems.”’ The Massachusetts agricultural experiment station re- ports six analyses of such material showing the potash content to range from 3.76 to 8.82 per cent. With a moisture content of 10.6 per cent, the average potash per- centage was found to be 6.44. Such tobacco stems are also rich in nitrogen besides containing small quantities of lime and magnesia. The potash present in the dried stems may be very largely removed by mere extraction with water, and even the insoluble potash residue must, in the process of decomposition, become very readily available to plants. 1 Bul. 21, R. I. Agr. Exp. Sta., January, 1893. POTASSIC FERTILIZERS Bao 383. Indian corn cobs. — It has been shown that In- dian corn cobs contain an average of about 6.8 per cent of potash and that the ashes made from them contain about 50 per cent of potash,! hence the ashes of corn cobs have a greater total fertilizing value, per ton, than muriate of ’ potash or the high-grade sulfate of potash. 384. Potassium nitrate. — One of the oldest and best known sources of potash, until the discovery of the Ger- man potash deposits, was “‘niter,” or potassium nitrate. This material usually contains from 12 to 14.5 per cent of nitrogen, in addition to 44.5 to 45.5 per cent of potash. Potassium nitrate is especially valuable for agricultural purposes wherever it is desirable to avoid the sulfuric acid and chlorin which are present in the German potash salts. Unfortunately, the supply is so limited, and the price in consequence so high, that it only occasionally comes into close competition with the German potash salts and the Chilian nitrate of soda. Nevertheless, there have been several years during the last two decades when the American farmer might have effected a decided saving in the purchase of his fertilizer supply had he bought potassium nitrate instead of the usual potash salts and nitrate of soda. A discussion of the methods used in the manufacture of potassium nitrate are to be found elsewhere (Section 241). 385. Potassium carbonate. — In the Caucasus there exist many factories for the manufacture of potassium carbonate, which is sold on the basis of 90 per cent of pure potassium carbonate. The chief impurities are sodium carbonate, 5 per cent; potassium sulfate, 2 per cent; and potassium chlorid, 6.5 per cent. In 1906 eleven such factories were reported in Russia. This material, like 1K. 8S. R., 17 (1905-1906), 1054. 934 VERTILIZERS potassium nitrate, is also to be recommended whenever chlorids and sulfates must be avoided; but it is more applicable to soils of an acidic character than to those well supplied with basic ingredients. I used in large quantities, it has a tendency to dissolve humus and to bring about deflocculation of the mineral matter, and consequently its use on certain soils may be disadvan- tageous. 386. History of the German potash deposits. — The German potash salts, which to-day constitute one of the most valuable possessions of any country of the world, were at the outset looked upon as a hindrance in the pro- duction of common salt. Salt works had already existed in Stassfurt, Germany, for a long period of time. They were at first the prop- erty of the Duke of Anhalt, they then passed into other hands, and in 1796 were sold to the Prussian “ Fiscus.”’ In the years from 1830 to 1840 common salt was discovered by borings made south of the Harz Mountains, in the Thuringian basin. The brines there were so favorable for the manufacture of salt that the weak brine at,Stassfurt could not be used in successful competition with them, and hence the Stassfurt works were finally closed in 1860. On April 3, 1839, a boring was begun at Stassfurt, and in 1843 at a depth of 256 meters the upper covering of the salts was met. It was then continued for 325 meters in the salt, without reaching the bottom of the deposit. The result of this undertaking was entirely unexpected, as well as a great disappointment at the outset, for instead of securing a saturated solution of common salt the saline solutions also contained large amounts of magnesium chlorid and potassium chlorid. It was concluded, how- ever, by Doctor Karsten and Professor Marchand that POTASSIC FERTILIZERS 235 at greater depths common salt would be met, and in 1852 the sinking of two shafts was begun. At the end of five years common salt was found at a depth of 330 meters ; but in reaching the deposit it was necessary to penetrate 250 to 280 meters of potassium and other salts. Soon thereafter similar discoveries were made at Neu Stassfurt, Léderburg near Stassfurt, and at Douglashall near Westeregeln. In a word, boring followed boring; not only north of the Harz Mountains, but to the south- ward and elsewhere, and mine after mine was opened at such frequent intervals as to increase the number, soon, to more than 150, thereby taxing the ability of the newly or- ganized German potash syndicate to control the situation. 387. Americans buy a German potash mine. — Finally the Virginia-Carolina Chemical Company of the United States purchased a German mine, and on July 1, 1910, when the proposed renewal of the German potash syndicate failed, large contracts for potash salts, continuing for sev- eral years, were made by certain mine owners with Ameri- can fertilizer manufacturers. 388. The famous potash contracts. — The reign of high prices for potash salts and the end of the former great Ger- man monopoly seemed now to have arrived. At this junc- ture the Reichstag passed a measure, practically creating a government monopoly of the potash salts. This situation soon led to diplomatic exchanges on the subject between the United States and Germany. As a result of this and subsequent agitation a new syndicate was formed, and the American contracts have finally been otherwise adjusted or withdrawn. 389. Mode of occurrence and distribution of potash deposits in Europe. — In the course of the search for these saline deposits in Germany, it has been found that they are 236 FERTILIZERS not confined to any particular geological formation, for they occur from the Permian to the Tertiary, though the deposits near Stassfurt underlie the ‘‘ Bunter” sandstone of the Triassic period. The following shows the arrangement of the deposits in the order from top to bottom in which they are more commonly found in the vicinity of Stassfurt : — Alluvial deposits. Diluvial deposits. “ Bunter ”’ (Brown) sandstone (Triassic). Gypsum, anhydrit, red clay, ete. Newer common salt (a luter secondary formation, frequently lacking). Anhydrit (anhydrous calcium sulfate). Salzthon.! Carnallit region. Kieserit region. ‘‘ Abraum”’ salts.” Polyhalit region. Older common salt. Anhydrit. Frequently kainit is found in the upper part of what is essentially the carnallit region, but its presence is not universal. Schénit, sylvanit, and many other minerals also occur in these deposits, though not usually in great quantities. 3890. The chemical composition of the more important potash salts is given in the following table : — 1 The Salzthon is made up of three layers, consisting at the bottom of calcium sulfate, in the middle of magnesia (uncombined) and alumina, and at the top of clay and from 40 to 50 per cent of magnesium carbonate. This forms an impervious and protecting cover for the potassium and magnesium salts below. 2A term applied because these salts were over, and in the way of getting at, the common salt, which necessitated their removal. « 237 POTASSIC FERTILIZERS 0'0€ | 9°08 | T'S 0°06 | O'16 | oF LPP | 297 | Ss GOS | 269 | TT 8°99 | 6°29 | 9°0 6°S¢G | G26 | 9 IT OSPF | 667 | oS S1¢ | 236¢ | 20 GL |2L06 FCLIPLI|SP OG | Soils beac PCL |S GL | 2°ct ae > = < Bow o Bx Sp |. = esl 3 | 5 z g _ OM HSVLOg qvaLoy eeguoice Sooner UaALV AA NI ATA VIOSN] IVINALVIY | | FOS®)0 ‘aLVATOG WAITV(D SORES HAS COA IOBN ‘qIMOTHD WarIdog 7103 ‘dIMO1HD WAISANDV IT ATA _ TQM mn : eps! | aIlw¥otHy) WOISsvLod elapse HANS ad N FOS7IN ‘ELVATOG WOISANDVI Socles Aso 4 marc ant ¥'0S 9°06 Go L6 on a Nn | 'OS°M ‘aLVATOAG WOISSV.LOg . . . . . . . . . . . . ysejod jo yuso tod QE wNUITUTUT ‘sqyes oINUvU YSe}IOg . . . . . . . . . . . . yseyod jo yuoo sod QZ urnuTTUTUT ‘sy[es oINUBUT Yseyog “* * 4ue0 red G/—0) “°° gud Jed Gg-—98 ysejod jo oyemnyy * gueo rod GG§-06 :surjeurmopoid spoTyg “TT OO bee acid © vIsouseUl pue ysejod jo a3Rj[Ng CY een eee ued 10d aes ac a ysejod jo aqyeyyng :Sployyo ULo1j oaqy} ApTBIU ‘SUIBUTUIOpsId SayRyING “| S7]DY painjov{nun Py ‘payouquaau0,g 7 tot tt (,B1eg,,) wasery 5 mn . . . wide oes qluBayAg Pe he, Satipenee ge Eh ES ee eee ne sD apni) [Inyo Ny LIVg 10 ANVN GONVLUOMN] IVYALTINOIUDYW AO SLIVG HSVLOd NVWUGf) AO NOILISOdWO)) ADSVINGOUTG ADVUGAY 238 FERTILIZERS 391: Duration of the deposition of potassium salts. — In the common salt are to be found thin bands of anhydrit which have been taken to represent the records of yearly deposits of gypsum during the colder season of the year. Based upon this and other features connected with the deposits, it was estimated, in 1864, that they might have been formed in 1500 years; but later estimates! place the time at from 10,000 to 13,000 years. At all events there seems to be no doubt that the deposition took place in a salt inland lake either fed by springs or having for a long time a continued or intermittent connection with the ocean. 392. Natural deposits of potassium salts elsewhere. — Up to the present time no discovery of large and important deposits has been made aside from those in Germany and a few in Austria. The occasional rumors of really im- portant discoveries in the United States still lack confir- mation. The discovery of such deposits at any time need not, however, be a matter of surprise, for it would seem that elsewhere than in Europe, lying above the salt de- posits of like origin, the potassium and magnesium salts of the mother liquors may likewise have crystallized out ; and they may also have been similarly preserved from the action of water by a natural protecting cover, just as they are by the ‘ Salzthon ” in Germany. 393. Kainit.— The most important of the natural salts, used directly as a fertilizer, is kainit (see analysis, p. 237), which, though it contains potassium sulfate, also carries large quantities of chlorids. It is used somewhat extensively in Europe, due in part to the low transportation charges. Kainit has been employed to some extent in the 1 Die Salzindustrie von Stassfurt und Umgegend von Dr. Precht, Stassfurt, 1889, p. 5. POTASSIC FERTILIZERS 239 United States for direct application to the soil, though its chief use has been in compounding ‘“‘ complete ’’ commer- cial fertilizers. The employment of kainit in fertilizer mixtures is usually indicated by the fact that their chlorin content, in such eases, is usually a little more than twice as great as the per cent of potash. Because of its chlorin content, kainit is to be avoided in the growing of sugar beets and tobacco, and also in the production of potatoes, if they are intended for starch manufacture. This is dueto the depressing effect of chlorin upon the starch and sugar content of certain plants, pro- vided that the application is made in the spring in which the crops are grown. In the case of tobacco the chlorin affects injuriously the color of the ash, and also the burn- -ing quality. Extended experiments in Europe have dis- closed the fact that good crops may be secured, and that this ill effect may be avoided, by using extra heavy appli- cations of kainit in the year preceding the one in which these sensitive crops are to be grown, and by omitting it en- tirely the following spring. It has been found, in such cases, that no serious losses result from leaching, and the subse- quent efficiency of the potash is not materially endangered. 394. Sylvanit and carnallit.— Another crude but less abundant salt, often applied directly to the land, is syl- vanit. This consists chiefly of chlorids and contains about 12 per cent of potash. It is sold in Europe at a lower price than kainit. Carnallit.—In Germany even the crude carnallit, containing about 9 per cent of potash, is also applied directly as a fertilizer; but it can neither be transported long distances nor can it be stored with safety in moist , places because of its hygroscopic character. 240 a FERTILIZERS 395. Muriate of potash. — The manufactured potash salt exported most extensively from Germany is the muriate of potash. The grade chiefly employed in agri- culture is the one containing from 48 to 50 per cent of potash, equivalent to from 80 to 85 per cent of potassium chlorid. The remaining 15 to 20 per cent consists chiefly of common salt, associated with small amounts of sodium and magnesium salts and a little water. 396. High-grade sulfate of potash.— The grade of sulfate of potash most commonly manufactured and sold for agricultural purposes in the United States is that con- taining from 47 to 48.5 per cent of potash, or about 90 per cent of potassium sulfate. This is usually designated as “high grade ”’ sulfate of potash, in order to distinguish it from a lower grade which contains large amounts of magnesia, in addition to potash. The small amounts of other ingredients in this potash salt are given in the pre- ceding table (p. 237). 397. Double sulfate of potash and magnesia, or double manure salt. — Following the foregoing manufactured potash salts in agricultural importance, in the United States, is the double sulfate of potash and magnesia, also known as “double manure” salt, containing from 25 to 27 per cent of potash, or approximately 50 per cent of potassium sulfate. The fact that this salt also contains 34 per cent of magnesium sulfate (MgSO,), and that it is essentially free from chlorids, makes it especially ap- plicable for soils which may possibly lack magnesia, and for situations where sulfur is possibly needed or where chlorin should be avoided. This salt should not be employed as a source of potash on soils already relatively too rich in magnesia. At the present time potash in the two sulfates costs, POTASSIC FERTILIZERS 241 in the United States, about one and one-quarter cents per pound more than in muriate of potash. The double sulfate of potash and magnesia has been used by Goessmann and Brooks at the Massachusetts experiment station with especially good results, in com- bination with other fertilizing ingredients, in the manuring of apple trees. 398. Double carbonate of potash and magnesia.— The double carbonate of potash and magnesia is a hydrous salt, also prepared in Germany, which has been used in several instances with excellent results in the United States. The material, according to an analysis made at the Massa- chusetts experiment station, was found to contain 18.5 per cent-of potash and 19.5 per cent of magnesia. In experiments at the Rhode Island experiment station it was found especially helpful in cases where not only potash but also an alkaline treatment of the soil was demanded; hence it is to be recommended wherever magnesia is not already present in too great amounts and where muriate of potash and sulfate of ammonia either fail to produce their full effect or are toxic, because of an acidic condition of the soil. 399. Silicate of potash. —A silicate of potash for agricultural use, containing from about 24 to 27.6 per cent of potash, has been prepared in Germany and dis- tributed in this country for experimental purposes. It was thoroughly tested by Brooks in Massachusetts and found to be a valuable fertilizer, ranking in efficiency between the muriate and the high-grade sulfate of potash. It is, however, of less interest than otherwise, because its manufacture is said to have been discontinued. 400. Potassium carbonate (Pearl ash). — Potassium carbonate (Pearl ash) and so-called “‘ potashes,”’ consisting R 242 ‘ FERTILIZERS of potassium carbonate and potassium hydrate, have been used as fertilizers to a small extent, and alsé in compost ‘ heaps. The former compound has found considerable application in the growing of tobacco. In experiments at the Rhode Island experiment station, covering a period of seventeen years, it has been found to give, with most crops, materially better results on a silt loam soil of acid character than an equivalent amount of potash in muriate of potash. Had the soil been alkaline at the outset, or nearly so, doubtless the reverse might have been true, as was found by W. P. Brooks in certain experiments in Massachusetts. . ; 401. Greensand. — A natural potash mineral of very low grade, but yet of some fertilizing value, which-has been used more or less extensively as a manure, at points near where it occurs, is ‘‘ greensand” or ‘ greensand marl.” This has generally been supposed to be a sea-bottom deposit, but it has recently been asserted that similar zeolitic compounds are probably formed by the action of magmatic waters. Greensand occurs widely, but. the deposits of chief interest in the United States are found in New Jersey. According to Cook, the material has an average content of about 5 per cent of potash, and it often contains in addition from 1 to 2 per cent of phosphoric acid. The greensand is a hydrated silicate of iron and potassium, a species of glauconite. Its action is slow, as might be expected, and the effects of a single heavy application are visible for a dozen years. It, like the other zeolites, is capable of being decomposed by hydrochloric acid, and hence it readily parts with the lime, magnesia, soda, and potash which it contains. Much virtue is ascribed by many writers to these zeolitic POTASSIC FERTILIZERS 243 compounds by reason of the fact that the bases are mu- tually interchangeable, and because of the prominent part they are supposed to play in giving to the soil its ability to absorb and hold lime, potash, and magnesia, when they are applied for manurial or amendatory purposes. It has been proposed by H. Wurtz ! to utilize the green- sand as a source of potash by fusing it with calcium chlorid, a method employed recently by Cushman and others for treating potash feldspars. 402. Phonolite, nepheline, alunite, leucite, and feld- spars as sources of potash. — It was suggested long ago by Storer? and others that certain feldspars (orthoclase feldspar, K,0 - Al,O3 - 6 SiOz, if pure, contains 17 per cent of potash) might possibly be so finely pulverized as to make them valuable fertilizers. Especial interest was recently awakened in the subject by Cushman,’ who claimed to have found feldspar, thus prepared, of decided value in the growing of tobacco. It has been shown by F. Schacke, Tacke, and Popp,’ and by H. von Feilitzen,> that powdered phonolite and nepheline ((Na - K),0(Al,O3 - 2 SiO.)) were of some value as potash fertilizers, but were far inferior to the Ger- man potash salts. The results with feldspar and with alunite were, however, too poor to make them worthy of consideration as practical potassic fertilizers. The value of finely ground feldspar has also been carefully studied by Hartwell and Pember.6 They employed a finely ground product capable of passing a screen having 1 Storer, Agriculture, 2 (1897), 487. 2 Agriculture, 2, 1897. 3 Bul. 28, Office of Public Roads, U. S. Dept. of Agr. 4Chem. Ztg., 35, 1222; Abs. Chem. Abstracts, 6, 1048. 5 Deut. Landw. Presse, 38 (1911), 737, 738. 6 Bul. 129, Agr. Exp. Sta., R. I. State College. 244 FERTILIZERS No potassium 11 grams ground potash ’ 2 erams sulfate feldspar (IKeO, 9.09 %) of potash Fig. 24. — TREATMENT OF MILLET. 2.75 g. 6.88 g. 11.00 g. 0.50 g. 1.25 g. 2.00 g. No potas- Ground feldspar Sulfate of potash sium Fig. 25. — TREATMENT OF WHEAT. POTASSIC FERTILIZERS 945 200 meshes to the linear inch, and containing about 9 per cent of potash, 3 per cent of soda, and less than 0.4 per cent of lime. The work was done in pots which were supplied regularly with water to the optimum limit, where- by the conditions for bringing the potash into solution were far better than those usually met with in farm practice. In the course of these experiments, beans, wheat, and Japanese millet (Panicum crus-galli) were grown. As a result it was found that the feldspar possessed such slight value as a fertilizer that no one could think of using it to replace the German potash salts. It has been proposed that leucite (K2O - Al,O; - 4 SiO,), containing 22 per cent of potash, might be heated with salts of lime or soda whereby the solubility and efficiency of the potash for plant production would be increased. Although it is admitted that much is gained by such treat- ment, yet the product has never been placed in successful competition with the German potash salts. CHAPTER XVIII THE THEORY AND PRACTICE OF POTASH FERTILIZATION Tue fact that the ocean contains far more sodium salts than potassium salts is explained on the ground that sodium is far more easily removed than potassium, from its zeolitic and other combinations, by the natural pro- -cesses of leaching. This is also well illustrated by the well-known fact that in the natural weathering of certain basic rocks the relative potassium content increases pro- gressively, whereas the relative sodium percentages be- come less. 403. The alleged ill effects of the chlorin of potassium and other salts. — According to A. Mayer,! calcium and magnesium chlorids are not. particularly injurious to meadow grasses. It is asserted by L. von Wagner that chlorids are not good for beets and potatoes, but he doubt- less refers to, their depression of the sugar and starch con- tent, which can be avoided by making the app the preceding year. It has been explained by O. Loew? that the ‘i effect of chlorids is probably due to the liberation of hydro- chloric acid in the plant cells and to the fact that, unlike nitric and sulfuric acids, little of it is assimilated, on which account the accumulation soon reaches toxic limits. In discussing the beneficial action of the carbonate, sul- 1 Lehrbuch der Agrikulturchemie (1886), 295. 2 Bul. 18, U. S. Dept. of Agr., Div. of Veg. Phys. and Path., p. 18. 246 POTASH FERTILIZATION 247 fate, nitrate, silicate, and phosphate of calcium, Ullmann ! says that calcium chlorid is injurious to plant life. It is stated by Griffiths,? based upon observations by Jamieson and Munro, that potassium chlorid is a plant — poison and that investigations in England and on the con- tinent of Europe have shown it to be an unreliable potash manure. It must, however, be recognized that the danger was greatly overdrawn by Griffiths in view of the fact that enormous quantities of muriate of potash are used throughout the world, with unquestionably good results. Certain early experiments by Nobbe,’ with buckwheat, have been very generally cited in the past in support of the alleged benefit derived by plants from chlorin, but — A. Mayer‘ holds that Nobbe attached undue weight to the matter. Nevertheless, observations on potatoes by Pfeif- fer® are said to indicate that chlorin was helpful, yet Pagnoul found, on the contrary, that chlorin was injurious to the growth of potatoes when grown on a sandy (sili- cious) soil. It should be recalled in this connection that am- monium chlorid has also been used by some experimenters with good results, whereas others consider it a plant poison. 404. Reasons for the diversity of ideas concerning chlorids. — In an attempt to throw light on the reason for the quite contrary views of so many leading authorities, Wheeler and Hartwell ® experimented with several different chlorids. Calcium chlorid was highly toxic to potatoes on an acid soil, but either caustic magnesia or slaked lime was shown to be capable of correcting the condition. : 1 Kalk und Mergel (1893), 9. 2A Treatise on Manures, p. 225. 3 Landw. Vers.-Sta., 6, 118; also 13, 398. 4 Landw. Vers.-Sta., 49, (1901). 5 Landw. Vers.-Sta., 49, 349-385. 615th An. Rpt. R. I. Agr. Expt. Sta. (1902), 289-304. 248 FERTILIZERS Magnesium chlorid was not found to be toxic for barley under the same conditions, yet ammonium chlorid was exceedingly toxic. In the latter case the toxicity was wholly corrected by calcium carbonate. The same re- sult was also secured with caustic magnesia, after allow- ing ample time for it to become well carbonated in the soil. In other experiments in which ill effects were observed from the use of muriate of potash, these were completely overcome, and the fertilizer was made to produce normal results by the employment with it of basic slag meal or other basic substances. In field experiments at the Rhode Island experiment station, potatoes of excellent cooking quality have been grown annually, with few exceptions, for a period of twenty years with muriate of potash as the sole source of potash. These results followed, even though the potash salt was applied in the spring, immediately before planting. Slaked lime had, however, also been applied periodically to the soil, which may have been an important factor in bring- ing about such a result. From these various experiments it appears probable that the highly toxic effects, reported as due to chlorids, may often have been caused, in consequence of a lack of basic substances in the soil. In fact, Schultz, of Lupitz, demonstrated conclusively that occasional applications of marl were necessary on the light acid soil of his sec- tion of northern Germany, in order to insure good results from repeated applications of the German potash salts. It has been pointed out by H. Ley! that neutral salts prevent or check dissociation. It is possible, therefore, that the lessening or hindering of unfavorable dissociations, 1 Ber, der deut. chem. Gesell., 30, 2192. POTASH FERTILIZATION 249 induced in the soil by the use of chlorids, may account in some measure for the benefit derived from lime and other basic substances. 405. The use of chlorids increases the need of liming. — When chlorids of potassium and other bases are used on soils well supplied with carbonate of lime, double decom- positions result whereby the chlorin unites. with the lime and magnesia, forming the corresponding chlorids. These chlorids, in reasonable quantities, are not only not ob- servably toxic in the presence of an excess of carbonate of lime; but, owing to their high solubility, they readily leach away in seasons of heavy and frequent rainfall. This is true especially if the chlorid of potassium is applied a few months, or preferably the autumn or spring, preceding the growing of such crops as are most subject to injury by chlorin. Muriate of potash is reported by many as giving usually slightly greater yields of potatoes than the sulfate of potash, though the tubers are often claimed to be of inferior cooking quality. In regions of heavy rainfall, and where plenty of lime is used, the danger in this respect seems to be greatly lessened or overcome. 406. The fate of sulfate of potash in the soil. — Sulfates are less objectionable in the soil than the chlorids, for the reason that plants require and utilize considerable sulfur. Furthermore under temporary or long-continued anaérobic conditions due to heavy rainfalls, sulfates are readily reduced by bacterial action, with the result that sulfids are formed from which even so weak an acid as carbonic acid may disengage hydrogen disulfid, at the same time forming carbonates. When sulfate of potash is employed on soils rich in lime, one result of the exchange of bases is the production of 250 FERTILIZERS calcium sulfate. This salt is relatively insoluble, for about 400 parts of water are required to effect the solution of 1 part of it, whereas calcium chlorid s soon liquefies upon exposure to the air.- On this account, especially if the conditions are occasionally favorable to reduction, the soil may not become so rapidly depleted of its supply of lime when using sulfate of potash as when muriate of potash is used. 407. Concerning the retention of potash by soils. — It was already known in the time of Aristotle that common salt is partly removed from solution upon leaching it through sand or soil. It was also shown by Way, in 1850, that when sulfate and muriate of potash are applied to ordinary soils, the sulfuric acid and chlorin appear in the drainage waters combined with lime and magnesia, and that the potash is held quite completely and tenaciously in the soil in zeolitic (zeolites are combinations of alumina, silica, water, and the bases lime, magnesia, soda, or potash, or various combinations of these bases) and other mineral and organic chemical combinations. It is now maintained by physicists and physical chem- ists that the phenomenon of absorption may embrace three distinct processes: (1) a mechanical inclusion called imbibition, illustrated by the absorption of water by a sponge or by soil; (2) the partial taking up of the dissolved substance to form a new compound or a solid solution ! such as is claimed to result in the absorption of phosphoric acid, by lime, or by ferric oxid; (8) absorption which is 1A solid solution is a crystalline, amorphous, homogeneous solid capable of changing its composition with the changing concentrations of the liquid solution in contact with it. A definite compound, on the other hand, is ‘‘stable in contact with a liquid solution of its constituents over a measurable range of concentration.” POTASH FERTILIZATION Wo the concentration or condensation of the substance in solution on the’ surface of the absorbing medium. It has been held by Cameron that potash is probably held in soils by absorption. Notwithstanding that in laboratory experiments, in which relatively small amounts of soil are usually em- ployed, the removal of potassium from weak solutions of potassium sulfate and of muriate of potash is never complete ; yet the conditions are entirely unlike those in field operations, in which the amount of material is most minute in its relation to the great volume of soil. It may, nevertheless, be true that on sandy soils, which are greatly deficient in clay, silt, and vegetable matter, potash salts may, in extreme cases, be subject to moderate losses by leaching, and they should consequently be used with some caution. 408. The teachings of the Rothamsted investigations. — In the drainage waters from the unmanured experi- mental plots of the Broadbalk wheat field at Rothamsted, Voelcker found 1.7 parts of potash per million, whereas in the drainage waters from the other plats receiving as much as 300 pounds of sulfate of potash per annum, he found only 2.9, 3.3, and 4.5 parts per million. An ex- amination of the same soils by Dyer showed that about half of the potash applied, in excess of that removed by the crops, during a fifty-year period, was still present in the upper nine inches of soil, and much of it was still soluble in a 1 per cent solution of citric acid. Still further por- tions of the excess of potash were found in the second and third nine inches, which were also found to be soluble in the citric acid solution. 409. Various factors affecting absorption. — Absorption appears to be dependent upon at least the following factors : — ; AG ed FERTILIZERS (1) The solubility of the given substance in the solvent employed, although the relation is as yet unknown. (2) The character of the absorbing substance, though it Full ration of Full ration of potassium sodium carbonate carbonate Fic. 26. —-TREATMENT OF SPINACH. Both lots limed and fertilized alike with nitrogen and phosphoric acid. is uncertain in how far this is determined by the area of exposed surface and-by the character of the surface in- volved. POTASH FERTILIZATION 255 - (3) In a given solvent the rate of absorption of different substances in solution is variable, even with one and the same absorbing medium. ‘This is so marked in some cases that partial separations of two different salts in the same solution may be thus made. (4) Selective absorption from electrolytes, as when potassium chlorid is filtered through soil, cotton, or other absorbents. In this case the filtrate not only becomes less concentrated, but even contains free hydrochloric acid. (5) The rate of absorption increases with the concen- tration of the solution and with the amount of the absorb- ent or of its effective surface. 410. Potassium essential to plant growth. — It is fully accepted that potassium is absolutely essential to plant growth, even notwithstanding that it may, for many kinds of plants, be partially replaced by sodium, in connection with one or more of its possible functions. The degree, however, of even this partial replacement appears to be largely dependent upon the particular kind of plant involved. 411. Potassium aids carbohydrate formation. — It has been found that the curtailment of the potassium supply exerts a serious effect upon the formation of car- bohydrates, such as starch, sugar, and cellulose; and in actual field practice certain crops especially rich in starch and sugar seem to require its liberal employment. 412. Other functions of potassium. — It is now also held that potassium performs valuable functions in the formation of the proteins, and that it aids cell and nuclear division. It has also been asserted by Loew that potas- sium acts as a condensing agent, which would facilitate the building up of carbohydrates from formaldehyde, as Loew has previously suggested. 954 FERTILIZERS 413. Potassium increases the size of the individual grains of cereals.— In experiments by Hellriegel and Wilfarth it was found that, with the supply of phosphoric acid or of nitrogen curtailed, the quantity of grain was greatly lessened; but yet the weights of the individual kernels were but slightly, or not at all, affected. When, however, the supply of potash was curtailed, the size of the individual grains became smaller, and the formation and translocation of starch was soon interfered with or prevented. In the later years of the barley experiments at the Rothamsted experiment station, after a lack of potash became evident, it was found that the average weight of the grain per bushel for a period of fourteen years was greater where potassium salts were used in the fertilizer, and the average weight per kernel was increased thereby in an even far greater degree. 414. Effect of potassium on photosynthesis. — Other experiments at Rothamsted with mangel wurzels show that with the leaf production varying but little, the addi- tion of potassium salts to the other fertilizers increased the yield of roots nearly two and one-half times. When these roots were analyzed, it was found that the increase in weight was due almost wholly to the increased produc- tion of sugar and of other carbohydrates. It would appear, therefore, that the process of photosynthesis in the leaf and the consequent possibility of the storage in the roots of the products elaborated by the leaves, is largely regulated by the potash supply available to the plant. In this instance the crop of roots was increased, as a result of the use of the potassium salts, from 12 to 29 tons and the total product of sugar from 0.797 ton to 2.223 tons. POTASH FERTILIZATION 255 415. Potassium in connection with turgor. — Notwith- standing that many writers even yet refer to “ the func- tion ’’ of potassium salts as if potassium performed only the function which has just been discussed, it appears probable that there may be several. It has even been asserted by Copeland! that potassium is both a direct and indirect factor in maintaining the turgor of the plant. The importance of this conclusion may, however, be doubted in view of the work of De Vries,? who, though upholding for a time the importance of certain organic acids in maintaining turgor, concluded later that growth may occur without turgor and that rapid growth may lessen it. It is also asserted by Pfeffer that turgor can- not furnish the energy essential to growth, but that on the contrary it is a result of the conditions of growth. 416. The functions of potassium not necessarily shown by the result which its absence produces. —As concerns the association of potassium solely with the function of aiding in the formation and translocation of starch, Pfeffer * is of the opinion that phosphorus may be as necessary in that respect as potassium, and he affirms “that the function of an essential element is by no means directly indicated by the result which its absence pro- duces.” 417. Potassium as a neutralizer and carrier within the plant. — It has been pointed out by Shimper‘ that or- ganic acids are the normal product within the plant of the synthesis of the proteins. In experiments by Mercadente * 1 Bot. Gazette, 24 (1897), 411. 2 Bot. Ztg. (1879), 848. 3 The Physiology of Plants, translated by Ewart (1900), I, 141. ‘Zur Frage der Assimilation der Mineralsalze durch die griine Pflanze. 5 Abs. Jahresb. Agr. Chemie (1885), 257. 256 FERTILIZERS in which he grew certain species of Oxalis and of Rumex without potassium, it was found that only one-eighth of the normal amount of acid was produced, and that the oxalic and tartaric acids formed were in combination with lime. In this case, only small amounts of starch and sugar were present in the sap of the plants. It is known that the neutral and more especially the acid salts of potassium and oxalic acid which are normally formed in these plants, are toxic to them if they accumulate in undue quantities. Nevertheless, it has been suggested by Wheeler and Hart- well that potassium perhaps performs a valuable office in the plant by forming soluble combinations with some of these acid synthetical by-products, in which state they may be readily transported to other parts of the plant, where by their combination with lime they are transformed into comparatively insoluble and non-toxic compounds, and are eliminated from the circulation. In this case potassium would not only act as a neutralizer, but also as a convenient and even necessary transporting medium. 418. Potassium may contribute to the ‘“‘ luxury con- sumption’ of plants. —It has been shown by careful investigation in Germany that a certain minimum of lime, magnesia, potash, and soda is essential to plant growth, but that plants require, nevertheless, a certain excess of bases above these total minima which may be supplied indiscriminately by any one or more of them; for this reason, if there is a lack of the other bases, potas- sium may be helpful by virtue merely of supplying this so-called (though necessary) ‘‘ luxury ”’ consumption. 419. Certain functions and effects of potassium salts in soils. — In some cases potassium salts may perform a useful function in the soil by virtue of increasing the sur- face tension of the soil solution, by which the rate of the POTASH FERTILIZATION B51 capillary movement of water toward the surface and to- ward the plant roots is increased.! It is also asserted by King (l.c.) that the presence of salts in the soil lessens evaporation from the surface, so long as they remain in solution, and if they crystallize out they serve in a measure as a mulch. Attention has recently been called by Miintz and Gaudechon ? to benefit which they allege may result in certain cases from the addition to soil of soluble fertilizer salts, since they lower the vapor pressure of the water and induce a distillation, to the affected points, of water vapor from the soil below and from the air above. If soils are too open, the use of the German potash salts may gradually improve their physical condition, by vir- tue of the fact that they react with calcium carbonate, if present, to form potassium carbonate, which salt has a highly deflocculating action. If, on the contrary, a soil is exceedingly fine, like many clay soils, the potassium car- bonate may by the same action injure the existing con- ditions, rendering the soils too compact and consequently difficult to till. It may make them at the same time also less suited in other respects to support plant growth to the best advantage. In these particulars the varying effects are analogous to those resulting from the residual soda of nitrate of soda (Section 254). 420. The effect of potassium salts on legumes. — The beneficial effect of potassium salts upon clover and other legumes has long been generally recognized, and many soils which have been found to be deficient in potash have come to be termed “clover sick.” It is nevertheless true that clover sickness may sometimes be due to a lack 1 King, Text-book of the Physics of Agriculture (1901), p. 106. ? Compt. rend., 48 (1909), 253-258. Ss 258 FERTILIZERS of lime, to disease, or other conditions; and one is not necessarily justified in assuming which of the various causes of the failure of clover may need to be dealt with, without special knowledge of the particular locality and of the soil concerned. In view of the known promotion of the fixation of at- mospheric nitrogen by certain plants, including the leg- umes, when the associated bacteria are well supplied with carbohydrates, it appears that at least one way in which ‘potassium salts may be helpful to the legumes is by in- creasing the carbohydrate supply within the plant, by which the organisms of the root nodules are made to work more effectively. In the permanent grass experiment at the Rothamsted experiment station, the herbage in 1902, where a mineral fertilizer containing phosphates, sulfate of potash, mag- nesium salts, and sodium salts had been used in the past, was 55.3 per cent legumes; whereas where potassium salts were omitted from the fertilizer mixture, the legumes amounted to but 22.1 per cent; and where nitrogen was applied and the potassium salts were omitted, no legumes were to be found. 421. The effect of a lack of potassium on grasses and other plants. — On the plots of land at Rothamsted where potash was most deficient, the grasses very largely failed to produce seed and the stalks were weak and _ brittle. This was assumed to be due to an insufficient devel- opment of carbohydrates within the plants. It is further mentioned by Hall that the grass possessed an abnormal color, lacked chlorophyl, and exhibited other signs of malnutrition. The leaves of Swedish turnips developed under similar conditions a ‘‘ flecked ”’ appearance, mangel wurzels were attacked by a leaf-spot fungus (Uromyces POTASH FERTILIZATION 259 bete), wheat developed much rust, even when little was present elsewhere, and grass was attacked by various fungi. Whether the ill effects arising from a deficiency of potash were due to a lack of general vigor or to an altered com- position of the plant cells, Hall does not attempt to con- clude, although he inclines to the former view. Concern- ing these results, Hall cautions against giving too much weight to such effects, in general farm practice, since the manurial conditions were most unusual and had been developed during the long term of years in which the ex- periments had been in progress. 422. Potassium salts act best in wet seasons. — The effect of potassium salts upon wheat and barley, at Roth- amsted, has been found to be far more favorable in wet than in dry seasons, due possibly to its preventing pre- mature ripening. The yield of barley in a dry season was 18.1 bushels per acre without the use of potassium salts, whereas it was 30.8 bushels when they were employed. In a wet season the yield in the first instance was 34.9 bushels, and in the latter instance 41.4 bushels, per acre. It has been found, in the case of root crops, that potash hastens maturity ; however, in barley and wheat the migration processes are quite different from those involved in the storage which takes place in root crops. 423. A lack of potassium more serious for some crops than for others. —In the course of experiments which have been in progress at the experiment station of the Rhode Island State College since 1894, it has been found, where potassium salts were omitted from the otherwise complete fertilizer and sodium salts substituted for them, that clover and timothy (Phlewm pratense L.) largely, and in some cases completely, disappeared. Nev- 260 FERTILIZERS ertheless, moderate crops of redtop (Agrostis vulgaris With.) were still produced, although the plants gave evi- dence of probable faulty seed development. Where the potassium salts were omitted, dark spots appeared on the leaves of potatoes, and even a blackening of the entire leaf surface often resulted. This did not appear like, nor was it recognizable microscopically as being identical with, either the early or late blight of potatoes. The plants, as would be inferred, died prematurely. Notwithstanding that the conditions in this experiment and in those at Rothamsted were quite unusual, it may nevertheless be true that under conditions which exist in farm practice instances sometimes occur where plant diseases may become unusually severe, due to a lack of potash or of a sufficient supply of other plant food in- gredients, to insure normal plant development. 424. Potash conservation in the soil by sodium salts. — It has been shown by Wilfarth and his co-workers at Bernburg, Germany ; also at Rothamsted ; and by Wheeler and Hartwell in Rhode Island, that certain plants, when supplied liberally with sodium salts, take up materially greater quantities of it, and less of potash, than when no sodium salts are applied. In fact, in the case of the Rhode Island experiments, the conclusion seemed obvious that plants supplied with the necessary minimum of potash could, perhaps with equal advantage, use some soda to replace a part or all of the excess of potash which they might have removed from the soil, had it been present. It appears, therefore, that nitrate of soda and the sodium com- pounds associated with the German potash salts may con- serve, somewhat, the potash stores of the soil by prevent- ing a “ luxury,” or unnecessary, consumption of potash by the plant. CHAPTER XIX LIME AND ITS RELATION TO SOILS AND FERTILIZERS Lime has been shown not only to be a corrective, in the presence of an excess of magnesia or of certain other substances, but also to be absolutely essential to plant growth, and incapable of complete replacement by other plant food ingredients. 425. The occurrence of lime. — Lime is present in combination with carbonic dioxid and also with alumina and silica in many of the representative rocks of the earth’s crust. It may be present in soils in the form of minute crystals of apatite, or in other combinations of lime with phosphoric acid; likewise in gypsum (calcium sulfate), calcium carbonate, in zeolitic compounds, and as a con- stituent part of decaying vegetable matter. 426. Distribution and effect of limestone. — Carbonate of lime is widely distributed in the form of rock, and in many respects it is the most important form of lime found in soils. Notwithstanding the wide distribution of limestone rocks over most of the globe, there are nevertheless soils upon which it appears probable that lime is sometimes even needed as plant food, though perhaps in such cases only in connection with restricted classes of plants. Gen- erally, however, if | me is required at all, it is as a soil amendment, either in a neutralizing or flocculating capac- ity. Asa neutralizer it exerts a powerful influence upon 261 262 FERTILIZERS the character of the microscopic soil flora, thus vitally affecting ammonification, nitrification, denitrification, and nitrogen assimilation. Lime also affects the development of certain diseases, not only on the roots, but also on the aérial portions of plants. It is because of these many functions of lime in the soil and of the many cases of contradictory effects, dependent upon the character of the soil, upon the kind of plant grown, and upon the particular plant disease involved, Eire. 27. Clover, where before liming it could not be grown successfully. It was said to winter-kill, which was really seldom the case. that the problems connected with the use of lime are of a very complex character. 427. Kinds of lime used in agriculture. — ‘‘ Burned ” lime, “‘ rock” lime, ‘‘ stone ’’ lime, and “‘ builder’s ”’ lime are various names given to the final product after the car- bon dioxid of limestone or marble has been expelled by heat. In this process 100 pounds of pure limestone (cal- cium carbonate) lose about 44 pounds of carbon dioxid and yield about 56 pounds of calcium oxid (CaO, or lime). Most limestone is so impure that the product, after burn- ing, usually contains not more than from 95 to 98 per cent LIME AND ITS RELATION TO SOILS 2638 of lime; and certain highly magnesian limestones yield, upon burning, a product containing about 60 per cent of lime and about 40 per cent of magnesia. Dolomite is the most highly magnesian of limestones, and it contains before burning 30.4 per cent of lime and 21.7 per cent of magnesia. Magnesian limestones are common, yielding a burned Unlimed Limed Unlimed Limed Sulfate of ammonia Nitrate of soda Fic. 28. — TREATMENT OF Silene orientalis. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. product containing amounts of magnesia ranging from the merest traces to about 40 per cent. Burned limestone is often ground, without slaking, and sold, without further treatment, for direct application to the land. In other cases the lime is slacked by the addi- tion of about one-third its weight of water, when there results a fine, dry product known as “‘ water-slaked,’”’ or more commonly as ‘“‘ hydrated ”’ lime (Ca(OH).). This is proportionately poorer in lime than before slaking, on 264 FERTILIZERS account of the addition of the hydroxyl groups (OH). Frequently lime is slaked by mere exposure to the air, whereby it takes on water and carbon dioxid, form- ing a mixture of calcium carbonate and calcium hydrate. Upon long and complete exposure to the air, under the most favorable conditions, hydrated lime and air-slaked lime become practically reconverted into calcium car- bonate. Other sources of carbonate of lime for agriculture pur- med Unlimed Limed Unlimed Li Sulfate of ammonia Nitrate of soda Fia. 29. — CARNATIONS. - All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. poses are wood-ashes, the waste from the manufacture of acetone, soda, and from other industrial processes. The chief materials used for furnishing carbonate of lime are, however, ground shell marl, ground oyster shells, and ground limestone or marble. These are named in their order of availability. Ground limestone and marble are the least efficient, chiefly on account of their crystalline structure. 428. The effect of lime on nitrogen availability. — It LIME AND ITS RELATION TO SOILS 265 often happens in soils which are deficient in carbonate of lime that the application of burned, air-slaked, or hydrated lime, ground limestone, or marl has an almost immediate beneficial influence upon ammonification and nitrification. Cases are on record where the efficiency of certain forms of organic nitrogen, in soils, has been increased from two to a dozen times, solely as the result of a single heavy application of lime. 429. The effect of lime on denitrification. — The effect of lime on compact clay or silt soils is to cause several small particles to draw together by the process known as “ floccu- lation.”” Asaresult, the air more readily enters the soil, whereby the conditions are usually rendered less favorable for the destruction of nitrates, since denitrification is essentially a reducing or anaérobic process. In fact, Koch and Pettit 1 have shown that in soils with 25 per cent or less of water the denitrifying organisms lie quies- cent, but when the moisture content is increased, destruc- tion of nitrates begins suddenly ; and considerable nitro- gen is then liberated in the gaseous state It appears probable that the critical percentage of moisture would be found to vary somewhat with the physical character of the soil. 430. The effect of lime on soil texture. — As suggested in the preceding paragraph, liming greatly improves compact silt and clay soils, especially if they are in such condition that they tend to bake badly. This improvement is not only due to hindering denitrification, but also in conse- quence of the general effect of a more free circulation of air, the creation of conditions more favorable to nitrifica- tion, and finally, also, by virtue of increasing the penetra- 1Centralb. f. Bakt., II Abt., 26 (1910), 335-345, Abs. E. S. R., 23 (1911), 123. 266 FERTILIZERS bility of the soil by water, whereby surface erosion is greatly lessened. The storage of water in the soil is also increased, and its subsequent capillary movement is better regulated and adapted to properly supplying the needs of the plants. Such soils, after being suitably limed, are fit to work much earlier in the spring than those from which lime has been omitted. It is also true of light sandy and gravelly soils that the use of lime often improves their condition by the mere adding of fine material, which increases their lifting ca- pacity for water. Furthermore, it is claimed that by. the chemical combination of the lime with silica and alumina to form zeolitic compounds, the condition of the soil is not only rendered better from a physical standpoint, but also as concerns its ability to hold potash and other plant food elements. The physical character of light soils is also said to be affected favorably by the adherence of lime to the surface of the existing soil particles. In all cases heavy liming is to be avoided on light soils, especially in hot climates, and particularly if they are greatly deficient in vegetable matter. In no case should opportunity be lost to increase the supply of the latter, even though lime is used with great care and in small quantities. 431. The use of lime in connection with phosphates. — The presence of calcium carbonate in soils may be expected to insure that when superphosphates of any kind are applied to them, some of the monocalcium phosphate will revert with lime rather than entirely or chiefly with oxids of iron and aluminum, as might otherwise be the case. This is quite commonly of distinct advantage in view of the fact that the phosphates of iron and aluminum, when LIME AND ITS RELATION TO SOILS 267 once formed, are considered as being less available sources of phosphoric acid for plants, at least on acid soils, than tricalcium phosphate. They are also less soluble than the latter in weak acids, including even carbonic acid. Large applications of burned or slaked lime, or even of carbonate of lime, are said to be frequently important factors in liberating phosphoric acid already locked up in the soil in combination with iron and aluminum oxids, as has been pointed out by Dehérain.! The beneficial effect of applications of slaked lime upon the subsequent efficiency of roasted iron and aluminum phosphate, even for several years after the last applica- tion of each, has been most strikingly demonstrated at the agricultural experiment station of the Rhode Island State College.2 This benefit is usually assumed to be due to the long-continued reactions resulting from the gradual transformation of the calcium carbonate into the more active bicarbonate, which then reacts more effectively than the carbonate upon the iron and aluminum phos- phates. It is possible likewise that other more complex factors are also involved. 432. Lime as a destroyer of worms and slugs. — Much has been written of the effect of lime in destroying worms and slugs, and Storer * states that if but 3 to 4 tons of lime are applied per acre, some insects may escape destruction, but that it may be expected to be very effectual if from 7 to 8 tons of lime are applied per acre. It must be rec- ognized, however, that on sandy or other light soils one should seldom, if ever, use more than from 1000 to 2500 pounds of burned or slaked lime per acre, in a single ap- ! Traité de Chemie Agricole (1892), 525. 2 Buls. Nos. 114 and 118. 3 Agriculture, 2 (1897), 545. 268 FERTILIZERS plication. Itis but rarely that more than from 1 to 2.5 tons per acre would be required, on heavier soils, in order to accomplish such changes as are immediately desirable. For this reason it is believed that the practical significance of liming, as a remedy for slugs and worms under usual economic agricultural conditions, has been unduly emphasized. It has been suggested by English writers that freshly slaked lime or, preferably, burned lime should be scattered in clover fields or in stubble where insect pests are common. This should be done, however, at or after dusk, or before sunrise, since the effectiveness of the lime depends upon its coming into direct contact with the worms or slugs, which appear to be unable to withstand its caustic action. 433. Need of liming suggested by soil acidity. — Soils are commonly referred to as acid which quickly and intensely redden a blue litmus paper when brought in contact with it under suitable conditions of moisture. Unless such soils are very light and sandy, or are typical subsoils, they usually yield immediately, without previous extraction with hydrochloric acid, dark chocolate, brown, or black extracts, upon stirring them with water and dilute ammonium hydroxid. It has been pointed out by Cameron and others of the Bureau of Soils of the United States Department of Agri- culture, that finely divided or porous substances which can in no way be considered as acid, as, for example, cotton, have, nevertheless, the property of absorbing the base away from blue litmus paper, whereupon it gradually takes on the color of the acid or red litmus. It should be remarked, however, that this reaction between litmus paper and cotton takes place very slowly. On account of these and similar observations and because some soils LIME AND ITS RELATION TO SOILS 269 which impart a red color to litmus pa- per have not shown subsequent benefit from liming (conclu- sions drawn some- times without suffi- cient attention to the requirement of the particular plant), the relia- bility and value of the litmus paper test for ascertain- ing if soils are in need of liming, has been seriously ques- tioned from several sides. It has been shown,! however, that, notwithstand- ing this physical absorptive property of soils, such redden- ing of blue litmus paper does not re- sult in the presence of moisture and of calcium — bicarbon- ate. Again, if a con- siderable amount of Note Beets of Limed all kinds are greatly aided by the sodium when potassium is deficient, and nitrate of soda also lessens soil acidity. Nitrate of soda Unlimed Fic. 30.— MANGELS WITH VARIED TREATMENT. Limed Sulfate of ammonia All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. the better effect of the nitrate of soda than of the sulfate of ammonia on both limed and unlimed soil. Unlimed 1 Bul. 139, Agr. Expt. Sta., R.I. State College. 270 FERTILIZERS active calcium carbonate is present in a soil, the rain water, and the soil solution charged with more or less carbonic acid derived from the air, and from decomposing plant residues in the soil, must inevitably react with it to form calcium bicarbonate, the quantity of which would increase within certain limits with the quantity of carbonic acid present. For this reason the rapid and intense red- dening of blue litmus paper by a moistened soil, whatever the reaction may be ascribed to, is an indication of a suffi- cient lack of basic substances to possibly interfere with suitable bacterial development and with the growth of certain higher varieties of plants, unless lime or other basic substances are employed. 434. Liming the most economic basic treatment. — Whether, therefore, a soil is strictly acid or is sufficiently lacking in bases to require their addition, even if for other reasons than for the neutralizing of acidity, liming is suggested as a suitable remedy. In fact, no other basic treatment, excepting possibly in some cases with magnesia, is either so economical, so lasting, or is it followed by such general good results, as liming. 435. Chemical methods for determining the lime re- quirements of soils. — Many methods have been pro- posed from time to time for determining the lime require- ments of soils, as, for example, (1) the adding of lime-water to the soil, evaporating, and determining the lime remain- ing uncombined, and (2) the bringing of soil in contact with calcium carbonate and the measurement of the carbon dioxid evolved either at the usual or higher temperatures. In the latter case the period of treatment must be very brief, on account of the progressive destruction of organic matter and the consequent liberation of carbon dioxid from it, which is in no way related to the reaction sought. | LIME AND ITS RELATION TO SOILS Ort Soils are sometimes extracted with water, and the watery extract is titrated ‘by use of a suitable indicator, taking cognizance of the probable presence of free carbonic acid in the extract. The foregoing are but a few of the methods proposed for the quantitative measurement of the lime require- ment of soils, but all fall short of perfection for practical purposes for the reason that they may give the total of basic absorption and chemical combination, or they may give only a fraction of this requirement. The true end point of the reaction in some cases is difficult to determine, and, furthermore, the amount of lime actually demanded to give the best results can only be approximated for certain selected groups of plants, and even the individual members of a group may vary among themselves in this respect. It is also true that amounts of lime far less than are shown by some of these quantitative tests are actually preferable, for certain crops, to the full amounts in- dicated. It is nevertheless true that certain of these methods, in the hands of one having a practical knowledge of the differences in plant requirements, when applied to un- known soils in conjunction with tests of soils the require- ments of which have been previously determined, may have very great value. On the other hand, however, they may lead to very erroneous and faulty conclusions as to the treatment, if placed in the hands of one having solely a knowledge of the chemical and laboratory side of the problem. 436. The effect of lime on vegetable decay. — It is mentioned by Storer that lime performs valuable func- tions in the soil by coagulating organic matter. If burned or slaked lime is mixed with relatively fresh 2i2 FERTILIZERS vegetable matter; the first effect is to retard decomposition, but if decay has already progressed to a considerable ex- tent, its introduction, in reasonable amounts, is likely to hasten decomposition almost from the outset. In fact, the action of lime in compost heaps is generally so well understood as to require no more than passing mention. Lime is also highly important in hastening ammoni- fication and the subsequent formation of nitrates from vegetable matter ; because, in order that nitrification may be active and progressive, there must be present some base Unlimed Limed Unlimed Limed Sulfate of ammonia Nitrate of soda Fic. 31. — CRANBERRIES UNDER VARIED TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. The cranberry is shown to thrive best on soil so acid as to be destructive to mangels. such as lime, magnesia, potash, or soda to combine with the nitric acid as it is formed, for otherwise the accumula- tion of acid soon inhibits the activity of the nitrifying organisms. 437. The effect of lime on nitrogen content of humus. —It must be remembered that in the early stages of the destruction of vegetable matter, the losses of carbon and hydrogen are relatively great, due to their ready transfor- mation under usual soil conditions into water and carbonic acid. Thus the organic residue becomes for a time, on LIME AND ITS RELATION TO SOILS ais the percentage basis, continually richer in nitrogen. In this connection it should be stated that it has been shown, on a soil greatly in need of liming which was kept for many years chiefly in hoed crops, that liming lessened to a con- siderable extent the total humus removable by extraction with ammonium hydroxid (‘‘ matiére noire ”’ of Grandeau), but that the percentage of nitrogen in the humus was dis- tinctly greater than before, thus showing the same general action of lime on material already well humified, in an acid soil, as on vegetable matter in a less advanced stage of humification. This tendency of the nitrogen percent- age to rise, after liming, is of interest in connection with observations by Hilgard and others to the effect that the higher the percentage of nitrogen in the humus, the greater becomes the availability of its nitrogen to plants. This helps also to explain the high fertility of soils well supplied with calcium carbonate which have become heavily charged with decaying plant residues. 438. Rational rotation and the turning under of sward should accompany liming. — The ideal condition is reached when a grass, clover, alfalfa, or other sod, plenty of barn-yard manure, straw, or green crops are introduced into the soil with sufficient frequency to maintain a suit- able supply of vegetable matter with which to insure proper tilth. This material also furnishes food to the organisms which assimilate atmospheric nitrogen and at the same time, through the action of lime, yields carbonic acid to act upon the mineral constituents of the soil. These residues also furnish to the plant considerable sup- plies of available nitrogen as ammonia and soluble organic matter, but primarily as nitrates. 439. Avoidance of liming to conserve humus not wise. — The idea that organic matter should be kept from de- wu: 274 FERTILIZERS struction in the soil as long as possible, and that liming should be avoided because it hastens such destruction, is wholly exploded by the recent investigations of the mi- croscopic soil organisms and of their several beneficent functions ; nevertheless, liming should not be overdone. Sufficient lime in its burned, hydrated, or air-slaked condition, or as calcium carbonate, should be applied, to imed Unlimed Limed Unlimed L Sulfate of ammonia Nitrate of soda Fic. 32. — ASPARAGUS DIFFERENTLY TREATED. All fertilized alike with potash and phosphoric-acid. A lke amount of nitrogen was used in each case. It should be noted that a fourth bundle is lacking at the left. This was because every plant died on the plot which received sulfate of ammonia but no lime. bring about a reasonably rapid humification of the vegetable matter, but at the same time care must be taken that this latter supply is reasonably maintained. In this con- nection it should be stated that it is universally understood that the repeated employment of slaked or burned lime in unduly large quantities without stable manure, green manures, the turning under of sward, and without proper fertilization must be avoided, or dire consequences are LIME AND ITS RELATION TO SOILS oT5 likely to follow. This is not only true as concerns the exhaustion of available potash and phosphoric acid, but also because of the serious destruction of the vegetable matter already in its various stages of decomposition. Nevertheless, the frequent sweeping condemnation of the use of slaked or burned lime without regard to the cost of transportation and other conditions affecting its use is equally to be avoided. On account of their ready availability, such forms of lime should usually be applied at intervals of from four to seven years, and, if employed on suitable soils, in reasonable quantities, and at the right point in such rotations as involve the periodic turning under of a good grass sod, no fear of material injury to the land need be entertained. 440. Carbonate of lime versus slaked or burned lime. — At the present time in the United States certain experi- ments conducted at the agricultural experiment station of the Pennsylvania State College are being extensively cited in the agricultural press, and elsewhere, as a basis for the unqualified denunciation of the use of burned and slaked lime. Conditions of the Pennsylvania experiment.—In the foregoing experiment, however, neither fertilizer nor stable manure was used. Slaked lime was applied at the rate of two tons per acre every four years, immediately before Indian corn in a rotation of Indian corn, oats, wheat, and clover. In comparison with it, like amounts of cal- cium oxid were used in ground limestone. In the former case the liming should preferably have preceded the seeding to wheat and clover, and the order of the rotation should have been reversed to give an opportunity for a favorable trial of the slaked lime. In the case of the lime- stone the application was divided into two equal parts, each 276 FERTILIZERS — being applied in alternate years, thus giving it a distinct advantage. As a result of the excessive quantity used, and of the application of the slaked lime at the wrong point in the rotation, it actually depressed many of the yields of Indian corn. The quantity of lime applied in the Pennsylvania ex- periment in twenty years on the basis of the four applica- tions, assuming a content of 70 per cent of calcium oxid, was 11.200 pounds of actual calcium oxid per acre. The soil was furthermore not greatly in need of liming, as has No lime Ground limestone Hydrated lime Fic. 33. — ALFALFA WITH TREATMENT UNDER FARM CONDITIONS. All fertilized alike with potash and phosphoric acid. Quantities of lime having the same total neutralizing value were used in each case. since been shown by Brown, and as indicated also by the fact that no great injury arose from several repeated applications of ammonium sulfate on other plots. It appears, therefore, that slaked lime was not only applied at an unfavorable time, but also in excessive quantities. Slaked lime highly beneficial in the Rhode Island ex- periments. — In striking contrast to the foregoing results, slaked lime has been used most successfully during a period of twenty years in several crop rotations at the agricultural experiment station of the Rhode Island State College, on land so greatly in need of lime at the out- LIME AND ITS RELATION TO SOILS QT set that beets, spinach, and lettuce could not be grown successfully without it or other alkaline fertilizers or ma- nures. This soil was, furthermore, so greatly in need of lime that a single small application of sulfate of ammonia became immediately toxic. It is interesting to note, however, that even under these extreme conditions the total quantity of calcium oxid employed (including any magnesium oxid present) was equivalent to less than 3200 pounds of calcium oxid, per acre, in an interval of nineteen years. Even though in most of the mstances in the Rhode Island experiments, fertilizers were applied exclusively, the crop yields, as a rule, have been well main- tained, and in general less fertilizer has been used in the later than in the earlier years. ‘The preceding experience shows, therefore, that too much alarm should not be occasioned by the results of experiments which have been conducted under unnatural conditions, and with unreasonably large quantities of slaked or burned lime. Slaked lime becomes quickly carbonated. —It must further be borne in mind that recent investigations have shown that slaked and burned lime, if applied in reasonable amounts, change quickly in the soil into the form of cal- cium carbonate; hence it is essentially, as concerns subse- quent effect, as if it had been applied as such at the outset. In the course of earlier experiments made by Heiden, he concluded that in some cases lime remained in a caustic state in the soil for years; it appears, however, that he assumed that all lime found soluble in water and capable of producing an alkaline reaction was necessarily present in the soil as calcium hydrate. The falsity of this assumption is evident in view of the fact that calcium carbonate, if placed even in distilled water, is somewhat soluble and will 278 Limed Unlimed Limed FERTILIZERS Unlimed Sulfate of ammonia Nitrate of soda Fig. 34. — CANTALOUPES DIFFERENTLY TREATED. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. cause it to give an alkaline reaction. Furthermore, car- bonic acid, which is always present in the rainfall and in the soil water, increases decidedly the alkaline reac- tion, by virtue of forming calcium bicarbonate. Again, salts of lime formed by other weak acids may themselves give an alkaline reaction in water. This experiment by Heiden has been widely cited by various writers as a rea- son why hydrated or burned lime should not be applied to soils, yet had they taken the pains to investigate the circumstances, it would have been found that the con- clusion of Heiden was not justified by the experimen- tal method which was fol- lowed. The bearing of _ the Maryland — station experi- ments. — Still another ex- periment, made at _ the Maryland agricultural ex- periment station, has been generally cited in the United States as showing great superiority of calcium LIME AND ITS RELATION TO SOILS 279 carbonate over slaked or burned lime. In this case the soil was admittedly deficient in both available potash and phosphoric acid, and it was only in certain of the eleven years covered by the experiment that any fertilizer was applied, although its need was indicated by the small size of the crops which were harvested. In this case marl and ground oyster shells were compared with stone lime and burned oyster shells, as well as with burned magnesia. It appears, however, upon an investigation of the circum- stances that the total quantity of marl probably contained from 400 to 450 pounds of potash and approximately 48 pounds of phosphoric acid, and that these substances may readily have become limiting factors in connection with the yields. In fact, it seems probable, in the light of this circumstance, that enough available potash and phos- phoric acid may have been secured by the crops from the marl, in many or all of the cases, to have accounted for the greater yields which it often produced. As concerns ground oyster shells, they often contain nearly .5 per cent of nitrogen and over .1 per cent of phosphoric acid, which may have given them some advantage over the burned lime. The fine matter associated with the marl used in the Maryland experiments may have improved the physical character of the soil. It is especially significant, likewise, that in some cases the burned magnesia‘and burned oyster shells actually gave larger crops than at least the ground oyster shells. It appears probable, also, that the Maryland plots were not, in all cases, sufficiently uniform in char- acter to justify some of the conclusions which have been drawn by others from the experiment. In view of this fact, and of the other circumstances mentioned, undue weight has apparently been attached to these results as a basis 280 FERTILIZERS for discrimination against slaked or burned lime. In fact, Director Patterson, who made the experiment, still recommends slaked lime for many agricultural purposes. Views of certain eminent European authorities. — In conclusion it should be said that such eminent European authorities as Dehérain in France, and Orth in Germany, though fully familiar with the dangers which may arise from the unintelligent and inordinate use of burned or slaked lime, nevertheless, recognize the great agricultural value of these forms of lime in specific cases, when used in No lime Lime as top-dressing in ‘ Lime harrowed in spring after seeding before seeding Fic. 35.— Timotuy. ALL SEEDED THE SAME AUTUMN. The lime in both cases was from the same lot, and was weighed out at the same time. reasonable amounts, and under ordinary conditions of culture. 441. The penetration of lime into soils. — One of the usual recommendations regarding lime is to harrow it into the surface of the soil, for the reason that it tends to work downward. There can be no doubt but that the various forms of lime will be carried downward to a con- siderable extent both by mechanical washing and in solu- tion as bicarbonate and otherwise, especially in soils which are sandy and open, and which are relatively de- ficient in vegetable matter. LIME AND ITS RELATION TO SOILS 281 On upland soils which are very compact, like certain silts and clays or fine soils containing large quantities of vegetable matter in advanced stages of decomposition, the chance for the descent of lime to the lower levels, excepting as it leaches through as nitrate, is very small, unless ex- cessive amounts are used. This has been well illustrated by the experience of Coville, who attempted to introduce lime-water into the lower levels of a soil rich in vegetable matter, only to find that all of the lime was held in a com- paratively thin layer of the surface soil. Another striking example of lime being retained in the surface soil is afforded in connection with the renovation of some of the acid peat (hoch-moor) soils of northern Ger- many. After liming, and other suitable treatment, these soils bore good crops for a few years, only to be followed later by frequent serious failures. Subsequent investiga- tion showed that this failure was due to the fact that the upper layer of soil had become so thin, as a result of the decompositions induced by the lime and by the system of drainage, that the crops suffered from drought by virtue of the fact that their roots did not penetrate to a sufficient depth to avail themselves of the permanent water supply. In fact, the lime had been of little or no value as a soil amendment below the level to which it was originally in- troduced, and the unlimed acid peat beneath was such an inhospitable medium that the plant roots would not pene- trate it to any practical extent. The unfortunate condition was corrected by subsoiling with a plow carrying knife at- tachments in the rear, and lime in a hopper on the beam, by which means lime was incorporated with the lower levels of the soil, after which the conditions for plant growth were again found to be favorable. The fact that plant roots will not readily penetrate an 282 FERTILIZERS inhospitable medium has been recently demonstrated by Reed in connection with some ingeniously devised experi- ments conducted in the laboratory of the Bureau of Soils of the United States Department of Agriculture. 442. The expulsion of ammonia from soils as a result of liming. — Experiments by Boussingault and others are often cited to show that so long as lime remains in the soil, in a caustic state, the formation of ammonia pro- gresses. Observations are also on record showing that Limed Unlimed Limed Nitrate of soda Sulfate of ammonia Unlimed Fic. 36. — ALFALFA UNDER TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen used in each case. actual losses of ammonia from limed soils have been noted in laboratory experiments; and likewise in fields, after heavy liming. In most pot experiments, however, the proportion of lime to soil will be found to have been far greater than those existing in practical field operations ; and even the applications of lime in the field were usually excessive and beyond what would be employed in rational agricultural practice. At all events, on all ordinary clay, silt, or loam soils the absorptive and chemical combining power of the soil for ammonia is so great that no material losses need be feared, wherever only reasonable applica- LIME AND ITS RELATION TO SOILS 283 tions of slaked or burned lime are made. This has been - fully established at the experiment station of the Rhode Island State College, by both pot and field experiments, in connection with which applications of from 1 to 4 tons, per acre, of slaked lime have been made. It has been observed, on unlimed soil, where sulfate of ammonia has been used, that ammonium salts, consisting chiefly of the carbonate or bicarbonate, sometimes appear on the surface as an efflorescence, some time after the sulfate of ammonia is applied; and in case the former salt were formed, losses of ammonia would. be expected to occur. Where lime was employed, and the conditions for nitrification were better, no such efflorescence has ever been noticed. It therefore appears probable that there are cases where the retention by the soil of the nitrogen applied as ammonia, may be actually furthered by the employment of lime. What has preceded illustrates the danger of generalizing from laboratory experiments, in which quite unusual conditions often prevail, or from field experiments in which excessive applications of lime have been used, as to what will transpire under the usual and normal conditions of farm practice. Nevertheless, such data serve as a constant and useful warning to those who must deal with very open, sandy soils, to the effect that there may be danger of serious direct loss of ammonia if either slaked or burned lime is used on them in excessive amounts. 443. The influence of lime on _ nitrification. — The influence of lime’ in promoting nitrification is now too well understood to require more than mere mention. It, or some other base, is essential to combine with the nitric acid as produced, and hence to prevent the uncombined nitric acid from accumulating to such an extent as to 284 FERTILIZERS inhibit the further action of the nitrifying organisms. For this purpose slaked lime, burned lime, or carbonate of lime may be used; although if either slaked or burned lime is employed, care should be taken not to use excessive quantities, for large amounts of slaked or caustic lime may check nitrification for a time. Such an apparent delay of the process of nitrification, for about ten days, resulted in one instance from the use of four tons of slaked lime, per acre, at the agricultural experiment station of the Rhode Island State College, on a good silt loam soil. Unlimed Limed Unlimed Limed Sulfate of ammonia Nitrate of soda Fic. 37. — CHICORY UNDER DIFFERENT TREATMENTS. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. It was noted, however, that no such delay followed the use of one ton of slaked lime per acre. At the end of the ten days the plants, in the first case, practically all recovered their normal appearance and made vigorous growth within forty-eight hours after the first sure signs of improve- ment were noticed. This improvement was doubtless coincident with the time when, by natural carbonation in the soil, the alkalinity of the lime had been reduced below the point where it could check the development of the nitrifying organisms. This experience suggests the experiments by earlier English investigators who LIME AND ITS RELATION TO SOILS 285 found that nitrification would not progress in undiluted urine until the alkalinity was lessened by the addition of calcium sulfate. This reacted with the ammonium car- bonate to form the essentially neutral salts, ammonium sulfate and calcium carbonate. It was found by Kellerman and Robinson that the ad- dition of calcium carbonate to a sandy loam soil was favorable to nitrification up to a limit of 2 per cent, or to a far greater limit than would ever be applied to agri- cultural soils. The application of magnesium carbonate, however, in excess of 0.25 per cent positively inhibited the action of the nitrifying organisms. 444. Effect of calcium and magnesium carbonates on ammonification. — Experiments by Lipman! have shown that, when mixed with soil, calcium carbonate depressed the formation of ammonia from cotton-seed meal, but stimulated it in the case of dried blood; whereas with magnesium carbonate the result was exactly the opposite. This may have been due to the difference in the relative calcium and magnesium content of the blood and of the cotton-seed meal, whereby the relation of the two was made favorable in one instance, and unfavorable in the other, to the vegetative growth of the ammonifying organisms ; as noted by Loew not only for certain lower organisms, but also for the higher agricultural plants. It has been suggested by Lipman that this difference in the action of the two carbonates upon organic matter of different kinds may explain the reason why the effect of magnesian lime is good on some soils and poor on others; also why where the magnesian lime fails, the purer lime is often help- ful. Such practical differences in the action of the two carbonates as arise in farm practice may, however, not 1 Centralb. f. Bakt., II Abt., 30 (1911), 173, 174. 286 FERTILIZERS only be due to the indirect effects suggested by Lipman and others, whereby more or less nitrogen is rendered available to the plants, but it may also be due to a direct physiological effect upon the agricultural plants themselves, which, according to Loew and his various co-workers, is often a very important factor in plant growth. Recent investigations by Gile in Porto Rico appear to show that much wider lime-magnesia ratios may exist, without causing injury to certain plants, than the conclu- sions of Loew and his fellow-workers would indicate. 445. General ideas as to the indirect manurial action of lime. — Lime has long been looked upon, whether ap- plied as hydrated, air-slaked, or fully carbonated lime, as a liberator of potash in the soil. This has been sup- posed to be due chiefly to mass action, whereby it may replace other bases in the zeolites and other similar com- pound silicates. Lime has also been shown by Morse and Curry! to increase the amount of potash freed, even from feldspathic and other potash-bearing minerals. 446. Results with sodium and magnesium salts il- _lustrate how lime acts indirectly. — An excellent illus- tration of a very similar liberating effect of magnesium and sodium is furnished by the experiments at the Roth- amsted station in England in connection with the wheat crop. These results are given by Hall from 1852 to 1901 inclusive. Sodium sulfate, potassium sulfate, and mag- nesium sulfate were added singly to separate plots of land ; to one plot all three were added, and a fifth plot was in- cluded from which all were omitted. In the course of the first ten years potassium sulfate gave smaller yields than any of the other sulfates, but where all were omitted the yields were markedly inferior. As time progressed the 1 Bul, 142 (December, 1909), N. H. Agr. Expt. Sta. LIME AND ITS RELATION TO SOILS 287 yields secured with sodium sulfate and with magnesium sulfate became relatively less, and the result with potas- sium sulfate in the subsequent decades of the experiment approached somewhat closely those secured with the combination of all three sulfates. Bearing in mind the recent work of Hart and Peterson,' it might be thought that these sulfates had been helpful by virtue of supplying additional sulfur to the plants, rather than as a result of their having liberated potash. If, however, such need of sulfur had existed, it would have been expected that where it was applied the percentage in the ash of the crop would have been increased, which was not the case. It must, however, be recognized that this is not always the case with nitrogen and perhaps not with other of the necessary elements. In all cases, nevertheless, the potash percentage in the ash of the crop was materially increased. The per cent in the ash in the case where no sulfates were added was 9.91; the respective percentages found upon the addition of sodium sulfate and of magnesium sulfate were 14.68 and 14.87; whereas, as a result of the use of potassium sulfate alone the potash in the ash rose to 23.28 per cent. With all three sulfates it amounted to 25.89 per cent. These changes were not accompanied by in- creases in the percentages of either soda or magnesia. 447. Fixation of potash after liberation by lime. — Notwithstanding that, in agreement with others, lime was found by Morse and Curry to have a marked solvent action upon the potash of feldspars, yet in the presence of considerable clay the potash was not found to have been rendered soluble in water. This was probably due to its having been fixed by the zeolitic compounds of the clay as fast as it was freed from the feldspar. This possibility is 1 Research Bul. 14 (April, 1911), Wis. Agr. Expt. Sta. 288 FERTILIZERS illustrated by experiments performed by Gerlach in which he found tricalcium phosphate more or less soluble in cer- tain weak acids, yet in the presence of iron and aluminum hydroxids no phosphoric acid was found in solution even after long-continued action. It was ascertained, however, in this case, that the phosphoric acid had been transferred to the iron and aluminum oxids, which fixed it as fast as the acid released it from its combination with lime. It appears probable, therefore, that as a result of the inter- action of the lime and feldspar, in the presence of the Unlimed Limed Unlimed Limed Nitrate of soda Sulfate of ammonia Fic. 38. — CrIMSON CLOVER UNDER TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. clay, the potash of the feldspar may have passed to some extent into zeolitic combinations, as a result of which its subsequent availability to plants may have become greater than in its original combination. It is possible also that in the presence of the clay considerable lime was also absorbed or fixed by zeolites directly, whereby the action of the lime on the feldspar was greatly weakened. . Indeed, Storer states that after submitting clay to the action of lime-water for a week or two, it will be found that an appreciable quantity of the clay which was previously insoluble in hydrochloric acid will then be dissolved, with LIME AND ITS RELATION TO SOILS 289 separation of gelatinous silica. In other words, by the addition of the lime to the clay, the formation of zeolites or compounds of similar character is apparently promoted. 448. Caustic lime attacks powdered quartz. — It has been shown by Stoeckhardt that caustic lime attacks not only precipitated silica, but also even powdered quartz previously extracted with acid, forming as a result hy- drated calcium silicate. The addition of carbonate of lime to soils often increases their power to hold potash, ammonia, and other bases, either by chemical or physical means, or perhaps by both. Furthermore, these bases may be set free again by the action of the sesquicarbonate or bicarbonate of lime which are continually being formed in soils stocked with active (the term “‘active”’ is used to designate such calcium carbonate as is not surrounded by particles of clay or other matter to such a degree as to be readily protected from attack by carbonic acid) carbonate of lime. 449. Losses of lime by leaching. — There are contin- ual losses of lime from the soil due to various causes :— (1) Carbonate of lime is even somewhat soluble in pure water, and certain salts in the soil solution are likely to increase the solvent action, as, for example, sodium chlorid, sodium sulfate, and certain ammonium salts. (2) The presence of carbonic acid carried to the soil in the rainfall, formed by absorption of carbon dioxid from the air, and produced by the decomposition of vegetable and animal matter in the soil, insures the gradual forma- tion of calcium sesquicarbonate and of calcium bicarbon- ate which may pass in some cases to a certain extent into the drainage water. The solubility of calcium carbonate has been shown to increase, at least within certain limits, with the amount of carbonic acid in the solution. U 290 FERTILIZERS (3) In the nitrification of manures, fertilizers, and of plant or animal residues in the soil, considerable calcium nitrate is formed which, not being held readily by the soil, is likely to be lost in the drainage unless the nitric acid therein is taken up by growing crops. At most seasons of the year and under favorable soil and cultural conditions, excepting in the case of a long-continued and excessive rainfall, there is but little loss by this means. (4) A considerable depletion of lime results in soils from the use of sulfate of potash, or sulfate of magnesia, but more especially from application of potassium, sodium, and magnesium chlorids, since the resulting calcium chlorid is far more soluble than calcium sulfate. Further- more, in case the soil is well stocked with vegetable matter and it becomes so wet as to temporarily exclude the air, calcium sulfate may be reduced to calcium sulfid, which in contact with carbonic acid may be decomposed into hydrogen disulfid and calcium carbonate, whereby some carbonate of lime is regenerated in the soil. (5) Other salts. of lime are also somewhat soluble and may in consequence add to the losses by drainage. : It is on account of these and other tendencies to loss of lime by natural drainage, and on account of the trans- formation of the calcium carbonate into other chemical combinations in the soil, that care must be taken to insure in soils at all times a small supply of ‘‘ active ”’ carbonate of lime. 450. Coarsely ground limestone compared with fine limestone and marl. — It is on account of the continual loss of lime from the soil by drainage that most of the soils of the humid regions which are formed from conglomer- ates, granite, gneiss, certain shales, schists, and sand- stones, are usually deficient in lime. For the same reason LIME AND ITS RELATION TO SOILS 291 soils of limestone regions lying even but a few feet above marl, chalk, or limestone beds often become sufficiently exhausted of their carbonate of lime to require its supply to the surface soil. It must be obvious from what has been said that the coarser the particles of lime added to the soil, the longer some of them will remain as calcium carbonate, or, in other words, the longer some effect of a given application No lime Ground magnesian limestone Ground limestone Fic. 39. — ALFALFA TREATMENT ON FARM. All fertilized alike with potash and phosphoric acid. Quantities of lime having the same total neutralizing value were used in each case. On certain other soils in the same State, ground magnesian limestone was found to be superior to the ordinary ground limestone. will endure. It is, however, false philosophy to assume that the lime which endures longest in the soil is neces- sarily either the most efficient or the most economical. It is, nevertheless, possible that there is a limit of fineness which permits of the preparation of ground limestone in a single grinding operation, a high percentage of which will pass a sieve with from 30 to 60 meshes to the linear inch, at such low cost that it is better economy to use more of the coarser material than a smaller quantity ground to a greater degree of fineness. If, in each case, 292 FERTILIZERS the same amount of material, passing a 30 or 50 mesh screen, can be secured at the same price, the still coarser associated material will cost nothing, and hence the pur- chaser might do better, if the transportation charges were low, to buy the coarser product. In other cases it -may be better to use less of a fine, readily available, and efficient product, and to repeat the application at more frequent intervals, than to buy, for a larger sum of money, coarser material which, even though some of it will remain in the soil longer, will nevertheless tie up a large cash investment for a longer period of time. No definite rule can therefore be applied to these cases, since the fineness and character of the product, the rate of interest, the character of the soil, the freight charges, the cost of hauling by team, and other factors must de- termine the choice of the purchaser in individual cases. 451. Concerning the practical use of lime. —Burned _lime, finely ground or crushed, may be used at rates rang- ing from a quarter of a ton on certain light soils to two and one-half tons on extremely acid soils which are rich in humus, capable of immediate extraction with ammo- nium hydroxid. A third more, in weight, of air-slaked or hydrated lime may be used under the same circumstances, or somewhat more than double the quantity of ground limestone or marl. Care should be taken to learn from small experimental plots about what quantities of lime are necessary, on a given soil, to insure success with the special crops to be grown ; and this amount will often be found to be far short of the total ‘“ lime requirement,”’ as indicated by certain quantitative laboratory methods. Excessive liming is something to be especially avoided, for the natural tendency of farmers is to carry it to ex- LIME AND ITS RELATION TO SOILS 293 tremes as soon as the advantages from the use of lime have once been fully recognized. On rocky pastures which cannot be plowed, lime must obviously be applied to the surface; and for this purpose ground limestone, or, preferably, shell marl or wood-ashes, are much to be preferred to burned or slaked lime. On mossy lands, in bad general condition, small appli- cations of some form of lime may be made to advantage just before plowing; but the chief part of the application should be made afterward, when it should be immediately Li Unlimed Unlimed Limed Sulfate of ammonia med _ Nitrate of soda Fic. 40. —WaATERMELONS VARIOUSLY TREATED. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. and thoroughly harrowed into the soil. In all such cases the principle should be borne in mind that the nearer a particle of lime can be brought to each particle of soil, the better will be the result. For most purposes, in ordinary farm practice the har- rowing of the lime into the soil after plowing is to be rec- ommended, though on land which cannot be plowed, car- bonate of lime may be spread broadcast on the sod in order to bring in clover and certain nutritious grasses which may otherwise fail to thrive. 452. Pure lime compared with magnesian lime. — Instances are on record, as in the experiments by Pat- 994 FERTILIZERS terson,! in which burned magnesia in certain instances has given better results than burned lime, and there are, for example, certain soils, as in parts of New Jersey and else- where, upon which magnesian lime gives generally better results than pure lime. The reverse is also true in still other localities in New Jersey and elsewhere in other states. This is usually due to the presence in the soil of relatively much greater quantities of magnesia than of lime, and in such cases the use of highly magnesian lime may some- times become objectionable. Within a few years new and important light has been shed on the whole question by Loew and his various co- workers, which will be discussed in full in considering magnesia. As a general rule it is at least erring on the safe side if one avoids liming repeatedly with a highly magnesian lime, and uses, alternately, a purer grade of lime. 1 Bul. 110, Md. Agr. Expt. Sta. (1906), 13-21. CHAPTER XX LIMING IN ITS RELATION TO PLANTS Tue subject of liming is just as important in its rela- tion to plants as in its relation to soils and fertilizers, and in this respect the complexity of the whole question be- comes increasingly great with each new research which is conducted. 453. Plants may transform lime compounds. — The function of plants in aiding in the transformation of one lime compound into another suggests itself by the fact that lime is taken up abundantly by common sorrel ~ from soils in which carbonate of lime is practically absent. When once within the plant, the lime performs the valuable function of neutralizing and removing from the circula- tion, as insoluble calcium oxalate, some of the oxalic acid, the excessive accumulation of which is toxic even to the plant in which it is produced. This compound in its turn, like calcium acetate and other organic calcium salts, is readily broken up into calcium carbonate in the soil in the course of the normal processes of decay; thus actually tending in a slight degree to correct for other plants the soil.conditions which are unfavorable to them, but which in no way inhibit the luxuriant growth of the common sorrel. A study of other plants with this feature in mind will reveal other possibilities of a similar character. 454. Miscellaneous effects of lime on plant diseases. — If lime is applied to acid soils, it creates a condition far 295 296 FERTILIZERS more favorable to development of potato “scab” than that which existed. at the outset. This action is, however, by no means confined to lime, since sodium carbonate, barn- Limed Unlimed Limed Unlimed Nitrate of soda Sulfate of ammonia Fig. 41. — RYE UNDER TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. yard manure, or other substances which are of an alkaline character have the same effect. For this reason lime should usually be introduced into a crop rotation after, rather than preceding, the potato crop. It is also impor- LIMING IN ITS RELATION TO PLANTS 297 tant in all cases that the seed tubers should be treated with corrosive sublimate solution, as proposed by Bolley, or with formalin, in order to destroy any germs of the disease which may be present upon them. The dry spot of oats has also been recently observed in Europe to occasionally follow the use of lime. A some- what similar or identical disease, or a possible disturbance of physiological function of oat plants, has been observed on silt loam soil in occasional years at the agricul- tural experiment station of the Rhode Island State Col- ° lege. The evidence thus far at hand points rather to a disturbance of physiological functions. It is notable that the difficulty seems to depend, nevertheless, in a great measure upon the prevailing climatic conditions, for in certain seasons no injury has been observed. It was thought at first in Europe that the difficulty was confined to the moor (peat) soils, but it is now recognized as occurring also on sandy and clayey soils; and Hudig! believes it to be due to changes in the composition of the humus brought about by repeated applications of the lime, or by other physiologically alkaline fertilizers. The use of excessive amounts of lime or of other alkaline substances has been found to encourage a disease of to- bacco known as “ tobacco root rot”? which is caused directly by a fungus (Thielavia basicola), the development of which may be hindered by the use of acidic fertilizers. It ‘has been suggested also that similar treatment may aid in combating certain diseases of the ginseng. A striking illustration of the lessening of disease by the use of lime is afforded by the “ club-foot,” ‘‘ aubury,” or 1E.S. R., 25, 724; also Landw. Jahrb., 40 (1911), 613-644. 2 Cire. No. 7, Bureau of Plant Industry, U. 8S. Dept. of Agr. (1908) by Lyman J. Briggs. 298 FERTILIZERS Air-slaked lime Unlimed Fig. 42. — TREATMENT FOR PoTaTo Scas. Complete fertilizer in both cases. Calcium sulfate .~ Calcium chlorid Fig. 43. — TREATMENT FOR Potato ScaB. Complete fertilizer in both cases. LIMING IN ITS RELATION TO PLANTS 299 . “finger-and-toe ”’ disease of the cabbage, turnip, and other related plants of the Crucifere family. This is accomplished by the employment of especially heavy applications of caustic lime immediately following a badly diseased crop, and again just before the growing of crops subject to the disease. 455. Lime in connection with potato scab. — The ef- fect of lime in encouraging potato scab has been mentioned briefly elsewhere, but the subject is of such importance that it requires more than passing notice. Earlier ideas. — Prior to the year 1891 when Thaxter.! discovered that potato scab was caused by a fungus (Oéspora scabies Thaxt.), many observations had been made in Germany and elsewhere upon its appearance. Its occurrence had previously been attributed to lime and to many other substances, on the ground that they caused an irritation or injury to the surface of the tuber, and that in the attempt to recover from the injury the characteristic growth of scab devleoped. The work of Thaxter.— The laboratory investigations of Thaxter were supplemented by him by field trials of various substances for one season, in the course of which he found 60 per cent of scab when broken plaster and cement were used in the hill, whereas in alternate hills in which mixed fertilizer was used but 6 per cent of scab wasfound. Among other materials Thaxter also employed wood-ashes in the same manner as the broken plaster and cement. In this case but 7.5 per cent of scab resulted, whereas in the alternate hills without wood-ashes but with the mixed fertilizer 12.5 per cent of scab was observed. From the foregoing it is obvious that the results furnished no conclusive evidence of lime having promoted the devel- 1 An. Rpt. Conn. Agr. Expt. Sta. (New Haven), 153-160. 300 FERTILIZERS Calcium carbonate ; Calcium oxalate Fic. 44. — TREATMENT FOR PoTATO SCAB. Complete fertilizer in both cases. Calcium acetate Wood-ashes Fic. 45. — TREATMENT FOR PoTaTo Scas. Complete fertilizer in both cases. LIMING IN ITS RELATION TO PLANTS 301 opment of scab, since they were negative with wood-ashes, which doubtless supplied much more carbonate of lime than was present in the broken plaster and cement. The work at the Rhode Island experiment station. — Upon the conclusion of Thaxter’s work the matter was carefully investigated for a period of four years at the ex- periment station of the then Rhode Island College of Agriculture and Mechanic Arts! with the result that slaked lime, wood-ashes, calcium carbonate, calcium oxa- late, calcium acetate, sodium carbonate, and barn-yard manure were all found to encourage the development of potato scab to a most serious extent, in case the causative fungus was present on the “ seed ” tubers or was already existent in the soil. On the other hand, calcium sulfate, calcium chlorid, sodium chlorid, and oxalic acid either failed to increase the scab or materially lessened it. By the use of a complete fertilizer, even with badly scabbed “seed ” tubers, little or no scab ensued on soil which was quite acid. It was conclusively shown, also, in cases in which the soil was already badly contaminated by the fungus, and where it had been made favorable to potato scab by the use of alkaline manures or amendments, that treatment of the ‘seed’ tubers exerted no appreciable protective influence against scab. Owing to the fact that in Thaxter’s laboratory experi- ments the fungus failed to thrive well, not only on very acid, but also on very alkaline, media, it seems likely that the reason the wood-ashes failed to encourage scab, in his original field experiment, was that they were probably employed at rates far in excess of what would be usually applied to land, thus creating a strongly alkaline reaction, which may be just as protective against scab 1 Bulletins 26 (1893), 30 (1894), 33, (1895), and 40 (1896). ‘ 302 FERTILIZERS as a condition of extreme acidity. This explains also the reason why broken plaster and cement should have encouraged scab, for the active lime therein must have been relatively too small to produce such a degree of alkalinity as would have been produced by the combined action of the carbonates of lime, magnesia, potash, and soda, all of which may have been present in the wood- ashes. 456. Lime may be used and potato scab avoided. — Notwithstanding the tendency of lime to promote potato scab, it has been used periodically at the experiment sta- tion of the Rhode Island State College in several crop rotations in quantities amounting in the aggregate to about 3200 pounds of calcium oxid in a period of about twenty years, and yet without practical injury to the potato crops from scab. In this case, however, the lime is applied in the rotations immediately following the po- tato crops, at intervals of from three to six years, and the tubers are always treated with formalin or with corrosive sublimate solution before they are planted. The impor- tance of these precautions is obvious, in view of the fact that in certain of the experiments in Rhode Island, in which they were not taken, the scab fungus has survived saprophytically an interval of seventeen years without an _ intervening potato crop. 457. Lime may cause injury to pineapples. — It has been reported by Gile! that when lime is present in sandy soils, in excess, it may be a cause of pineapple chlorosis. In such cases treatment of the leaves and soils with iron salts, though said not to be feasible from an economic standpoint, proved to be an effective antidote. The treatment of the leaves is in accord with recent experi- 1 Porto Rico Agr. Expt. Sta., Bul. 11. LIMING IN ITS RELATION TO PLANTS 303 ments showing that inorganic fertilizers can enter plants effectively through the leaf. 458. The effect of lime on the size of potatoes. — Many Limed Unlimed Limed Unlimed Nitrate of soda Sulfate of ammonia Fic. 46.— OaTsS UNDER TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. exneriments on an acid silt loam at the agricultural ex- periment station in Rhode Island, covering several years, have shown that liming frequently results in increasing the total crops of potatoes. This effect is, however, in- 304 FERTILIZERS consequential compared with the great increase in the ‘relative per cent of large tubers, a point which is of decided economic importance. 459. Liming may hasten crop maturity. — The question of the influence of lime in hastening crop maturity has been much debated pro and con, probably for the reason that its effects are very different, depending upon the character of the soil, the crop, and other attendant con- ditions. If the physical condition of a soil were injured by liming, the growth of crops might be unduly prolonged; but if liming were to improve the physical condition, it would be expected that the maturity of the crops grown upon the soil would be hastened. If there were a lack in the soil of readily available nitro- gen, phosphoric acid, or potash, at the outset, to meet fully the plant requirements, the tendency would be to delay growth, and hence the final maturity of the crop. If, on the other hand, liming were to promote a sufficiently active ammonification and nitrification, or if it were to bring about a sufficient liberation of lacking mineral in- gredients to meet the complete needs of the plant, without material excesses, growth would follow rapidly from the outset, and maturity would probably be hastened. If a soil were very acid, and hence poorly adapted to the luxuriant growth of certain plants, liming would likewise be expected to hasten development and maturity. In this way one may account for the marked increase in large potato tubers mentioned previously. For similar reasons crops of onions have been observed to ripen from two to three weeks earlier on land which had been limed three times in the course of fifteen years than where the land had been limed but twice in the same interval. It has been LIMING IN ITS RELATION TO PLANTS 305 observed in cases where liming failed, or practically failed, * to increase the yield of Indian corn, that the maturity was nevertheless hastened from a week to ten days. On acid soils the effect of lime in hastening the maturity of cantaloupes and of kohl-rabi has often been found to be very marked. '? me : i Et ' 8 = 7 ™m ea 2] pa ry ™ cd m@ Limed Unlimed Limed Unlimed Nitrate of soda Sulfate of ammonia Fic. 47. — WHEAT UNDER TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case, In case a soil were already abundantly supplied with all needed forms of plant food, and large quantities of nitrates were to be produced, as a result of liming, this additional supply would naturally have a tendency to prolong growth at the expense of maturity, just as was found by Voorhees to be the case when repeated applications of nitrate of soda x 306 FERTILIZERS were made to tomato plants, in contrast to a single appli- cation at the outset. 460. Soils needing liming for some plants ideally adapted to others. — Soils giving strong and quick re- ; 5 : . FE 3 . “ ed Lee See ira ] wi | ba ta / \ & ‘a Limed Unlimed , Limed Unlimed Nitrate of soda Sulfate of ammonia Fic. 48. — BARLEY UNDER TREATMENT. All fertilized alike with potash and phosphoric acid. A like amount of nitrogen was used in each case. Comparisons with Figs. 41, 46, and 47 show that barley is more helped by liming than wheat, oats, or rye. actions with blue litmus paper and with ammonium hydroxid are frequently highly toxic to certain very sen- sitive plants, even though the soils have not been fertilized at all for many years with either chemical fertilizers or barn-yard manure other than perhaps the occasional LIMING IN ITS RELATION TO PLANTS 307 dropping of dung by horses or cows. It is not to be sup- posed that the ill effect upon certain plants is necessarily due in all cases directly to soil acidity, but perhaps chiefly in many cases to toxic iron compounds, toxic organic substances, or other deleterious compounds accompanying the lack of basic substances, or arising in consequence thereof, which are oxidized, catalysized, or otherwise de- stroyed as a result of the application of lime. 461. Details concerning the lime requirements of dif- ferent plants. — It is not safe in any event to generalize from experimental results secured with one, or even with several, plants in regard to the lime requirements of other plants in their relation to the soil. This is well illustrated by the fact that a soil rendered so toxic by the long-con- tinued application of ammonium sulfate as to absolutely inhibit the growth of the poppy, lettuce, beet, canta- loupe, asparagus, cress, onion, barley, clover, and a whole series of other agricultural and ornamental plants will yet produce better plants of the common sorrel, cranberry, or Silene orientalis than it will after the condition, so highly unfavorable to most plants, had been corrected by liming. With only the latter plants in mind, and provided one had not experimented with others, the natural assumption might be that agricultural soils are never so acid or so charged with toxic substances as to interfere with the growth of plants, for the worse the condition becomes for certain plants, within reasonable limits, the better certain others seem to thrive. Similarly, on the other hand, cer- tain plants are best suited by conditions of alkalinity or salinity which are totally destructive to the great majority of agricultural plants. On account of a lack of sufficient appreciation of these conditions, the agricultural press and even scientific pub- 308 FERTILIZERS lications often contain statements to the effect that legumes are in great need of liming, in order that they may develop root nodules and properly assimilate atmospheric nitrogen. Nevertheless, the Southern cowpea, serradella, and certain of the lupines are likely to be injured by heavy liming. Other legumes may. possibly be injured under the same conditions, whereas the alfalfa and winter vetch suffer seriously, for lack of lime, even where clover will still grow with moderate success. Not only the lupines (Lupinus), but also the beans (Phaseolus), differ widely among themselves as to their requirements for lime in its amendatory capacity. CHAPTER XXI GYPSUM AND WASTE LIME FROM INDUSTRIES RECENTLY gypsum has been employed in the United States to a smaller extent than formerly, whereas the use of ground limestone, burned lime, slaked lime, and waste lime from certain industries has increased. 462. Early use of gypsum. — Gypsum (land plaster or calcium sulfate) has been used as a fertilizer since the time of the earliest Greek and Roman writers. Much mystery surrounded its action in earlier times, which has been re- moved by modern discoveries in agricultural science. It is now available as ground gypsum and as a by-product of the manufacture of double superphosphate. 463. The source of some of the gypsum in soils. — In certain localities considerable calcium sulfate is present in soils naturally, and since the advent of superphosphates it has been added in that form to the land in considerable quantities, with but little thought on the part of the user that it was present in the usual commercial fertilizer which he was applying. Gypsum has also been added to soils incidentally, in some cases, in kainit, which is used by itself or as a fre- quent constituent of ready mixed commercial fertilizers. The effect of gypsum and lime on clover and other plants. — In Europe, generally, gypsum has long been considered as a specific for clover; and in many cases it has been found to give much better results than lime. Indeed, 309 310 FERTILIZERS Neither lime nor gypsum Gypsum Slaked lime Fig. 49. —TasLeE BEETS UNDER VARIED TREATMENT. The slaked lime and gypsum each supplied like amounts of calcium oxid. All fertilized with like amounts of potash, phosphoric acid, and nitrogen. Storer ! cites several such cases and mentions in the same connection that Gas- parin found it to work well on a soil containing 20 per cent and more of lime. In experiments at the agricultural experiment station of the Rhode Is- land State College it was found, on an acid silt loam soil, that, notwithstanding a striking gain in beets and clover resulting from the use of gypsum, the employ- ment of the same quantity of calcium oxid in air- slaked lime gave far better results. ; In order to throw light upon other similar discrep- ancies in the use of these substances, it should be pointed out that Gasparin was dealing with a soil well supplied with lime, in which the general conditions were not unfavorable to the growth of the particular crop concerned, whereas in the experiment made in 1 Agriculture, ete., Vol. 1 (1897), 326. GYPSUM AND WASTE LIME FROM INDUSTRIES 311 Rhode Island the soil was a silt loam essentially devoid of carbonate of lime and so deficient in bases as to quickly and intensely redden blue litmus paper and to yield large quantities of humus (‘‘ matiére noire” of Grandeau) upon extraction with dilute ammonium hydroxid, without previous extraction with hydro- chloric acid. It was also shown that applications of sodium carbonate, potassium carbonate, and burned magnesia very largely corrected the condition of this soil for beets and other plants, but that the corresponding sul- fates were of little or no avail. It is evident, therefore, that in Gasparin’s experiment neutralization of the soil was not needed, and gypsum was helpful probably chiefly because of the liberation of potash or possibly by virtue of supplying sulfur, both of which clover greatly needs. Gypsum may nevertheless also have been useful in liber- ating magnesia and phosphoric acid or in counteracting an improper relation between lime and magnesia, if such existed. The possibility of some indirect action in the experi- ment by Gasparin is well illustrated by experiments by Boussingault in which the application of gypsum resulted in raising very greatly, not only the percentage of lime in clover, but also the content of potash, magnesia, phos- phoric acid, and sulfuric acid. In the Rhode Island experiment generous applications of complete fertilizer were made in both cases, which would naturally have lessened any benefit arising from the possible liberation of plant food ingredients of the soil. 464. Gypsum poorer than lime on acid soils. — The chief factor causing the superior action of the slaked lime in Rhode Island was the fact that the prime difficulty with the soil was its acidity, which the lime could neutralize at 812 FERTILIZERS once, but which the gypsum could correct but little, if at all, until by possible processes of reduction some of the sulfate had been transformed into calcium sulfid and this in turn into calcium carbonate through the action of car- bonic acid. 465. Gypsum may yield calcium carbonate in the soil. — The formation of calcium carbonate from gypsum is in- dicated by the following equations : — (1) CaSO, +2 C = 2 CO, + CaS calcium carbon carbon calcium sulfate dioxid sulfid (2) CaS + CO, + H,O = CaCO; + H.S (volatile) calcium carbon water calcium, hydrogen sulfid dioxid carbonate sulfid It must be remembered, however, that these changes take place under anaérobic conditions, which are not likely to be vigorously maintained for a great length of time in fairly open, well-drained soil which is in good tilth. 466. Gypsum may furnish lime or sulfur as plant food. —It is possible that cases may occur where gypsum is useful by virtue of supplying either lime or sulfur to the plant, in the capacity of a plant food ingredient, but in general the explanation is more properly to be sought in an indirect manurial action, by virtue of the liberation of other plant food elements. 467. Factors determining the choice between gypsum and lime. — When dealing with soils which are acid and with plants readily subject to injury by such acidity or by the toxic substances which often accompany it, either slaked lime or calcium carbonate is likely to prove more effective as a soil amendment than gypsum. In the case, however, of nearly neutral, neutral, or alkaline soils, or of GYPSUM AND WASTE LIME FROM INDUSTRIES 313 plants that find therein optimum conditions, as concerns their chemical reaction, it is probable that gypsum will be found to act better than the other compounds of lime. 468. Gypsum as a retainer of ammonia. — Whereas much weight was formerly attached to gypsum as an agent for changing the ammonia of ammonium carbonate into ammonium sulfate, whereby its volatilization might be avoided, it has been found that much moisture is necessary to the change, and furthermore the reaction is only partial and even then reversible, so that the importance of gypsum in this connection, under many of the conditions pratti- cally to be dealt with, seems to have been much overes- timated. 469. Methods of applying gypsum. — For clover it has generally been found to be a good practice to apply the zypsum to the moist leaves when the plants are only a few inches high. Similarly, it has been applied with good results to potatoes by scattering it along the top of the drill after the plants are well up and immediately before cultivating them. It may of course be spread broad- cast, and then be harrowed into the soil, especially before seeding to clover and before the planting of other crops. 470. Gypsum as an oxidizing agent. — Mention has been made of the reduction of calcium sulfate to calcium sulfid, and it should be recognized that in connection with this process gypsum plays the réle of an oxidizing agent. It furnishes the oxygen for the destruction of the vege- table matter, which takes place through the intervention of the microérganisms of the soil. 471. Gypsum may sometimes aid nitri cation. — Owing to the capacity of gypsum to react with ammonium carbonate to form ammonium sulfate and calcium car- bonate, it has been shown by Warrington to be effective 314 FERTILIZERS in promoting nitrification in liquid manure or in manure heaps, where the reaction is too alkaline at the outset for nitrification to begin. 472. Gypsum a renovator of alkaline soils. — Gypsum has been shown by Hilgard and others to be an efficient substance for counteracting black alkali (sodium carbon- ate) in consequence of its reacting with it to produce sodium sulfate and calcium carbonate, whereby the al- kalinity is greatly reduced. 473. Effect of gypsum on the solubility of lime. — It has been shown by Cameron and Bell ! that the solubility of gypsum is depressed in an increasing degree as the amount of lime (CaQ) in the solution is increased, where- as with increasing amounts of gypsum in the solution the solubility of lime seems to be nearly the same as in pure water. 474, Gas-lime and lime from other industries. — ‘‘ Gas- lime,’ or ‘‘ gas-house lime” as it is sometimes called, should lie exposed to the air for some time in order to effect the destruction of certain poisonous substances, before it can be applied to the land with safety. The lime in the processes of purifying the gas is changed very largely into calcium sulfate, and hence it cannot perform the same functions as slaked lime, burned lime, or calctum carbonate. The lime waste from acetylene lighting plants is essen- tially hydrated lime, and it has been used agriculturally with good results. The same is true of the waste lime from beet-sugar factories and from other industrial works. It is always a wise precaution to have waste factory products examined by an agricultural experiment station 1 Jour. Am. Chem. Soc., 28 (1906), 1220; Bul. No. 33, Bur. of Soils, U.S. Dept. of Agr. (1906); Jour. Phys. Chem., 11 (1907), 273. GYPSUM AND WASTE LIME FROM INDUSTRIES 315 before attempting to utilize them for manurial purposes, for the reason that factory processes are subject to frequent changes, and the presence of some one or more substances toxic to plant life is not unusual in the residues from cer- tain industries. CHAPTER XXII MAGNESIA AS A FERTILIZER In 1851 E. von Wolff! pointed out the beneficial effect of magnesia upon plant growth, although Mulder be- lieved it was merely due to its. liberation of other plant foods. 475. Functions of magnesia in the plant.—It was shown by the work of Schmiedenberg? that magnesia was possibly of importance in connection with the forma- tion of the albuminoids. At present, however, magnesia is not believed to play a direct réle in connection with protein formation. According to E. von Raumer? magnesia performs useful functions in connection with the translocation of starch, though in this respect potassium is now known to be particularly important. It has been asserted by Loew and by Hilgard +? that magnesia serves in the plant as a carrier of phosphorus, where, according to Hilgard, it exists as dimagnesic-hydric phosphate. The fact that more magnesia is present in oily than in starchy seeds, supports this view, since lecithin, which is rich in phosphorus, is formed in cells rich in oil. It is furthermore stated by Reed that there 1 Erdmann’s Jour., 61 (1851), 15. 2 Zeits. f. Physiolog. Chem., 7, 205. 3 Die landw. Vers.-Sta., 29, 279. 4 Soils, ete. (1906), 382. 316 MAGNESIA AS A FERTILIZER il is often a very definite relation between the magnesia and the vegetable oils. It is also of interest to note that Ville found, when magnesia was omitted, that the yield of wheat fell from 337 to 123 grains. According to Bretfield | an increase in the dry weight of plants is impossible in the absence of magnesia. In experiments by Dassonville,? with magnesium sulfate, No lime Ground magnesian limestone Slaked Lime Fie. 50.— ALFALFA ON Farm. All fertilized alike with potash and phosphoric acid. Quantities of lime having the same total neutralizing value were used in each case. ‘it was found that, though delaying the growth of certain legumes at the outset, it became finally indispensable. The participation of magnesia in some of the most impor- tant synthetic processes of the plant is asserted by Stras- burger, Noll, Schenck, and Schimper.’ In brief, no one now questions that magnesia is essential to plant growth. 476. Conflicting ideas as to the action of magnesia. — According to Atterberg,! the compounds of humus 1 Pflanzenphysiologie (1884), 135. 2 Revue générale de Botanique, 8 (1896), 331; Abs. Jahresb. f. Agr. Chem. (1896), 260. 3 A Textbook of Botany, translated by Porter (1898), 173. 318 FERTILIZERS with lime are less soluble than those of humus and mag- nesia. It was asserted by Stutzer? as late as 1893 that soils usually contain sufficient magnesia to meet plant require- ments, yet D. Meyer,’ for example, attaches special value Fig. 51. — TREATMENT OF OaTs. 1. Unlimed. 2. Calcium chlorid in 1894 and 1895. 3. Same as 2, with addition of caustic magnesia in 1897. 4. Sameas 2, with addition of slaked lime in 1897. All fertilized alike with complete fertilizer. to magnesian lime as compared with the high calcium limes, in connection with the growth of certain legumes ; and Larbalétrier and Malpeaux report the use of magne- sium sulfate as advantageous for beets, for some years, in the Department of Pas-de-Calais, France. Similar results are also recorded by Stéckhardt, in Saxony, and like 1Svenska Mooskultur-foreningenstidschrift (1891), 121, 122; Abs. Centralb. f. Agrik. Chem, 2/, (1882), 298, 299. 2 Leitfaden der Diingerlehre, p. 16. 3 Landw. Jahrb., 29 (1900), 961. MAGNESIA AS A FERTILIZER 319 instances may be cited from experiments in Rhode Island,! and elsewhere in the United States. It has long since been observed that experimenters in different localities have sometimes secured quite op- posite results from the use of magnesia, as, for example, in the case of the good results secured by Ville when it was used for wheat and the ill effect on wheat noted by Passarini.? It has been pointed out by Storer that Tennant noted a poisonous action of caustic magnesia, yet in recent ex- periments at the Maryland experiment station caustic magnesia at the rate of 1400 pounds per acre gave in certain instances better results than the same amount of calcium oxid in ground oyster shells. In fact, many similar conflicting instances might be cited. It has been stated that Von Raumer, in 1883, pointed out the necessity of a proper relationship of lime to mag- nesia in connection with plant growth; and Knop called attention at an early date to the fact that in water-culture experiments certain calcium, potassium, or ammonium Salts were capable of counteracting the ill effects of an excess of magnesia, and he suggested the applicability of lime as an antidote for magnesia in field culture. Many other investigators have found lime an antidote for an excess of magnesia in field practice. Later, a theory was advanced by Loew? which may explain, in many cases, this interesting and important fact. 477. Loew’s theory concerning magnesia. — In brief, Loew holds ‘ that a calcium protein compound partici- 1An. Rpt. R. I. Agr. Expt. Sta., 17 (1903-1904), 230-234. 2 Bol. Scuolo Agr., 3 (1895), 140-142 ; Abs. Jour. Chem. Soc. (London), 72, No. 142, II, 587. 3 Die landw. Vers.-Sta., 41, 466-475; also Flora (1892), 368-394; Bul. 18, U. 8S. Dept. of Agr., Div. of Veg. Phys. and Path. (1889), 42. 320 FERTILIZERS patesin the organized parts of the nucleus and chlorophyl body,” and _ that when magnesium salts of the stronger acids are made avail- able to the plant, the lime as_ the stronger base would “combine with the acid of the mag- nesium salt, while the magnesia would enter into the place which the lime had occu- pied in the organized structure; the ca- pacity for imbibition would thereby be altered and adisturb- ance of its structure would result which would prove fatal. “On the other hand, judging from the laws of the action of masses, it would naturally be inferred that an excess of lime salts would remedy the evil effects by making the reverse Seeded to timothy, redtop, and “ Complete” fertilizer. Fic. 52. — Ciover, ReptTop, AND TIMOTHY, PROMINENT IN THE OrpDER NAMED. clover, the same as in Figs. 53, 54, and 55. Hydrated lime containing a small amount of magnesia. MAGNESIA AS A FERTILIZER Sa process possible.” It is not to be assumed, however, that all cases of injury arising from the use of magnesia are due to the reason given by Loew and his various co- workers, for other factors often come into play. It ap- pears probable, nevertheless, that there are certain fairly definite relations between lime and magnesia which are best for given kinds of plants, and yet for other plants they may be widely different. The recent work by Gile shows that in some cases the importance of the very close and definite relationship may have been overesti- mated. The investigation of this question is, however, yet in its infancy. There has unquestionably been too great a tendency to explain cases of injury arising from the use of magnesium salts on the basis of Loew’s theory, for in many cases some other explanation harmonizes far better with the observed facts... These attempts to support the theory of Loew by frequent unwarranted claims have resulted in awaken- ing unnecessary fear of magnesia poisoning, even in regions where magnesia is not present in soils in undue proportions as compared with lime, and where its applica- tion is often followed by good results. 478. The ratios of lime and magnesia in different soils. — It has been asserted by D. Meyer? that soils with an especially high content of magnesia, as compared with the lime, are quite exceptional; yet Loew ® cites analyses of twenty soils from different parts of Japan in which the magnesia exceeds the lime by from two to five times, and the relations of the two in the soils of Japan have been found to range from traces of lime associated with 0.475 1An. Rpt. R. I. Agr. Expt. Sta., 17 (1903-1904), 221-260. 2 Landw. Jahrb. (1904), Heft 3. 3 Tbid. (1905), 1338. ¥ $92 FERTILIZERS per cent of magnesia to such limits as 1.618 per cent of lime and 6.307 per cent of magnesia. Other analyses of Japanese soils are also cited in which quite the opposite relation was found to exist. Magnesia has also been found in excess of the lime in certain of the soils of Ohio, which have been greatly helped by liming, yet the benefit in this case may well be due chiefly to other effects than the correction of an un- favorable ratio between lime and magnesia. Indeed, 4 A aan Via A “ 3 ‘ae bi . . Sp c2 et LL IES Fic. 53. — CLover, REpDTOoP, AND TIMOTHY, PROMINENT IN THE ORDER NAMED. ‘ ® Hydrated magnesian lime with high magnesia content. ‘‘ Complete” fertilizer. Seeded to timothy, redtop, and clover, the same as in Figs. 52, 54, and 55. even Loew (ibid., p. 135) calls attention to the neutralizing value of both calcium carbonate and magnesium carbon- ate, and to their frequent beneficial action, in this capac- ity, upon the bacterial flora of the soil, which effects, he admits, may in certain cases be so great as to obscure the physiological effects due to correction of the calcium- ~ magnesium ratio. He also adds that otherwise in soils containing about equal quantities of lime and magnesia the yield of cereals would be depressed by an application of either. In order to arrive at the lime and magnesia available MAGNESIA AS A FERTILIZER BAe in the soil, Loew prefers an extraction of the fine earth with 10 per cent hydrochloric acid rather than with a 10 per cent solution of ammonium chlorid, which was em- ployed by Meyer. 479. Variations in magnesia content of different parts of the same plant. — Instances are cited by Loew! of certain seeds in which there are found one hundred mole- cules of magnesia to seventeen of lime, and yet in the leaves there were two hundred and twenty-four molecules of lime to one hundred of magnesia. 480. Concerning the alleged toxic action of magnesium chlorid.—It was suggested by Knop that in certain soils sulfate of potash should be employed rather than muriate of potash on account of the possibility that magnesium chlorid might otherwise be formed, which Knop regarded apparently as a positive plant poison. According to the theory of Loew, magnesium chlorid would be expected to have a toxic action upon plants, at leAst whenever the lime was deficient. In fact, he states? that ‘ calcium and magnesium chlorid have an injurious effect upon plants, probably on account of the liberation ‘of hydrochloric acid in cells, this not being assimilated like nitric and sulfuric acid and therefore accumulating to a noxious degree.”’ It has been stated by L. von Wagner * that calcium and magnesium chlorids are not good for potatoes and beets. It is obvious that excessive amounts of magnesium chlorid, like other salts, must inevitably be injurious to plant life; the degree of injury depending upon the kind of plant and the concentration of the salt solution. 1 Die landw. Vers.-Sta., 41 (1892), 473. 2 Bul. 18, U. S. Dept. of Agr., Div. of Plant Phys. and Path., 18. 3 Pflanzen-Produktions-Lehre (1874), 336. 324 FERTILIZERS A study of the effect of magnesium chlorid was made by Wheeler and Hartwell ! on a silt loam containing about 0.57 and 0.21 per cent, respectively, of ime and magnesia soluble in strong hydrochloric acid, as determined by the Hilgard method of soil analysis. The land had been planted to Indian corn for several years, without fertilizer or manures, until it would no longer produce a crop over 6 inches high in the course of a whole season. The experiments were made in galvanized iron pots 18 inches in diameter and 26 inches deep, with the bottoms sloping to an opening in the center. The pots were set in soil nearly to their tops over drain tile, which insured normal conditions of temperature and prevented the backing up of water into them from the surrounding soil. The first two years all of the pots received acid phosphate, nitrate of soda, and muriate of potash, and the third year dried blood, basic slag meal, and potassium-magnesium car- bonate (a product of the German potash works). The average yield of barley plants per pot the first year, with- out further treatment, was 43.7 grams, and upon the addi- tion of 19.2 grams of hydrous magnesium chlorid per pot the yield was 46.5 grams. By the use’ of 110 grams of calcium carbonate per pot in addition to the magnesium chlorid the average yield was raised to 67.9 grams; but when caustic magnesia was added at the rate of 44 grams per pot in place of the calcium carbonate, the average yield fell to 6.1 grams. The following year the application of magnesium chlorid was repeated, and spring rye was grown. The average yield with magnesium chlorid was 51.8 grams; the yield where calcium carbonate had also been applied, the pre- vious year, was 55.8 grams; and where caustic magnesia 1An. Rpt., R. I. Agr. Expt. Sta., 75 (1901-1902), 295-304. MAGNESIA AS A FERTILIZER 325 replaced the calcium carbonate, the yield was now 49.7 grams. The toxic action of the caustic magnesia, ob- served the first year, had now practically vanished. It was found that the addition of magnesium carbonate at the rate of 59.2 grams per pot, where the caustic magnesia had been applied the year before, resulted in a depression of the yield to 41.4 grams. This second year the check pots to which no magnesia had been added in any form gave an average yield of but 3.7 - grams. The third year the crop was oats, and the average yield with magnesium chlorid was 84.4 grams of oat plants per pot. Where calcium carbonate had been added two years before, the average yield was now 79.4 grams; that where caustic magnesia was used two years before was 87.9 grams; and the yield where caustic magnesia was used two years before, and magnesium carbonate a year before, was 82.5 grams. It is of special interest to note that the yield of the check pots as a result of using a basic magnesian fertilizer was now 88.7 grams. The magne- sium chlorid had not in this case proved materially or positively toxic, since the differences are within the reasonable limit of error. In view of the improvement in yield from the use of calcium carbonate and the injury from caustic magnesia the first year, it might have been assumed, on the basis of Loew’s theory, that the lime had been helpful by virtue of counteracting an undue propor- tion of magnesia; yet such a conclusion is impossible in view of the excellent results in every case in the last year, where magnesium salts were used as additions to the magnesium chlorid and the regular fertilizer. It has since been shown by field experiments that this soil had finally become so acid as to inhibit almost absolutely the 326 FERTILIZERS growth of timothy, clover, and barley, until the condition was corrected by the addition of calcium carbonate, potas- slum-magnesium carbonate, burned dolomite or slaked lime (slightly magnesian). This fact accounts for the .poor results of the second year in the check pots when muriate of potash and acid phosphate were used, and also for the toxic action of ammonium chlorid when used in an experiment under the same conditions as magnesium chlorid. This also explains the effect, the first two years, of calcium carbonate in more than counteracting the tox- Fic. 54.— Reptrop. (CLOVER AND TIMOTHY LACKING.) Complete fertilizer. No lime. Seeded to timothy, redtop, and clover, the same as in Figs. 52, 53, and 55. icity of the ammonium chlorid, and also the effect of the basic fertilizer made up of basic slag meal, dried blood, and potassium-magnesium carbonate, in correcting, in all cases, the conditions in the check pots in the third year. The foregoing results show that magnesium chlorid is less toxic on certain soils than ammonium chlorid ; and still other experiments with the same soil indicate that it is far less toxic than calcium chlorid. 481. Danger from using caustic magnesia and burned and hydrated magnesian lime. — The preceding results show that caustic magnesia was toxic at first when it was used in large quantities, even on a soil evidently in MAGNESIA AS A FERTILIZER 327 slight need of magnesia, but that when sufficient oppor- tunity had been afforded for it to become carbonated, it became useful. It is probably on this account that special care must be taken in employing a hydrated, air-slaked, or burned magnesian lime immediately before planting a crop, unless great care is taken to limit the quantity used to moderate applications, and to most thoroughly incorporate it with the soil. Such danger is obviously greater on light, sandy, and gravelly soils, lacking in moisture and vegetable matter, and less on heavier soils rich in vegetable matter, especially if they are of an acidic character. 482. The solubility of magnesium carbonate in its relation to practice and experiment. — According to Comey,! magnesium carbonate is more soluble than cal- cium carbonate in water, carbonated water, and in am- monium chlorid. It has also been shown by Treadwell and Reuter that one liter of water will hold only 0.385 gram of calcium bicarbonate in solution, but that the same amount of water will hold in solution at one time, not only 1.954 grams of magnesium bicarbonate, but also 0.715 gram of magnesium carbonate. For this reason there is much more danger of injury from heavy applica- tions of burned and slaked magnesian lime than from the pure lime, especially on soils but little in need of basic applications, and for plants which are particularly suscep- tible to such injury as may arise in consequence of the creation of an alkaline reaction in the soil solution. Not- withstanding that these figures may apply to magnesium carbonate, which is formed by the taking up of carbonic acid by slaked magnesian lime, it is doubtless not true of the magnesium carbonate in natural magnesite, dolomite, 1A Dictionary of Chemical Solubilities, London and New York, 1896. 328 FERTILIZERS or highly magnesian limestone; for Hilgard! has pointed out that magnesia in its native combinations leaches less rapidly from soils, than lime, indicating that the relative solubilities of artificial carbonates may be quite the re- verse of the natural compounds. In fact, the mineral magnesite (magnesium carbonate) is said to be probably insoluble in water and not to be affected by boiling with water or with aqueous solutions of alkaline carbonates.? Experiments conducted under the direction of B. L. Hart- well, at the request of the writer, have also shown that - ground magnesian limestone, sufficiently fine to pass a sieve with 50 meshes to the linear inch, was much less soluble in carbonated water maintained in a state of saturation than ground limestone passing a sieve of the same mesh. In fact, the solubility of the latter was ap- proximately three times as great as the solubility of the former. If, therefore, quick action is necessary, Magnesium car- bonate, if formed recently from burned magnesian lime, would be expected to correct undue acidity of soils rather more quickly than calcium carbonate; but natural mag- nesite, dolomite, or magnesian limestone might accom- plish it less quickly than natural carbonate of lime. It has been shown by H. Ley * that neutral salts check or prevent dissociation, hence magnesium carbonate as well as calcium carbonate may be expected to act favorably on acid soils in preventing dissociations of compounds possessing ions of a character injurious to plant growth. On the other hand, the high solubility of magnesium 1 Soils, etc. (1906), 383. 2 Davis, Jour. Soc. Chem. Ind., 25 (1906), 788; cited from Cameron and Bell, Bul. 49, Bur. of Soils, U. S. Dept. of Agr., 59. 3 Ber. d. deut. chem. Gesell., 30, 2192. MAGNESIA AS A FERTILIZER 329 carbonate, such as would be likely to be formed quickly from burned magnesian limestone in the soil water, and the possibility of creating by its presence alkaline condi- tions unfavorable to certain plants, has been very fre- quently neglected or ignored in farm practice and also in experimental work. In consequence, in certain instances very erroneous conclusions have doubtless been drawn. In fact, no experimenter can afford to neglect the possibility of such effects any more than he should, for example, the possible influence of such compounds upon the ionization of other salts, upon the bacterial life, or upon the physical character of the soil. 483. Ranges in lime and magnesia content of plants without material differences in yield. — It was found by Wheeler and Hartwell in pot experiments with spring rye in which the average yields of rye plants per pot were 50.5 and 51.3 grams, respectively, that in the former case, in which calcium carbonate was employed, the ratio of lime to magnesia was 6.3 to 1; whereas in the second instance, where magnesium chlorid had been applied, the ratio of lime to magnesia was ‘1.5 to 1. Results with mangels were also secured in connection with which, in addition to the regular fertilizer, caustic magnesia, sodium carbonate, and air-slaked lime were employed. When caustic magnesia was added to the usual fertilizer, the yield was 126.3 grams of air-dried mangel ‘ roots,’’ and the ratio of lime to magnesia was 6.4 to 1; when sodium carbonate was added, the yield was 131.3 grams, and the ratio of lime to magnesia was 1.6 to 1; when slaked lime was used instead of the caustic magnesia or sodium car- bonate, the yields in two cases were 148.2 and 132 grams and the ratios of lime and magnesia 4.4 to 1 and 38 to 1, respectively. Without further addition than that of the 330 FERTILIZERS regular fertilizer, the yield was 91.3 grams and the ratio of lime to magnesia was 4.2 to 1. Attention has been called elsewhere to the fact that plants may be physiologically relieved of certain excesses of lime by its crystallizing out within them as insoluble calcium oxalate and in some cases exteriorly as calcium carbonate. The former disposition is impossible in the case of magnesia, because of the solubility of the mag- nesium oxalate. It must be evident, therefore, that in Fic. 55.— Extrems Lert, Reptop anp WereEps. (No CLOVER NOR TIMOTHY.) No lime. No fertilizer. Seeded to timothy, redtop, and clover, the same as in Figs. 52, 53, and 54. any discussion of the ratios of lime and magnesia in plants, the possibility of such storing away of some of the lime in insoluble, and hence in inactive form, must be taken into consideration; yet in the instance here considered, it does not seem probable that this factor could have had much influence on the relation of the two. It appears, therefore, as concerns the ratios of lime and magnesia within the plant, that there may be in some cases very wide varia- tions without an accompanying difference in yield. 484. Desirable lime and magnesia ratios in soils and culture solutions. — According to Loew,! a relation of 2 of 1 Circular No. 10 (1909), Porto Rico Agr. Expt. Sta. MAGNESIA AS A FERTILIZER ool lime to 1 of magnesia in soils is to be desired, because it stands between that which is best for cereals, on the one hand, and for the legumes on the other; he points out, however, that the relative availability of the lime and magnesia present in the soil may nevertheless change these ratios materially, a difference not revealed by his chemical method of determining them. Furthermore, these generalizations, especially as to the legumes, may be hasty and subject to material modification, depending upon the individual legume concerned. It has been established experimentally by Furuta and Katayama! that the most advantageous ratio of lime to magnesia is 1 to 1 for rice and oats, 2 to 1 for cabbage, and 3 to 1 for buckwheat. It appears, in other words, in accord with the relatively greater amount of lime in the leaves, and of magnesia in the seeds, that plants with a great leaf surface may require relatively more lime. It was found by Bernadini and Corso that. the best ratio of lime and magnesia for maize was 2 to 1; for oats in water-culture it was 1 to 1; and in soil culture 2 to 1 was permissible ; but a depression in yield resulted with a ratio of 3 to 1. It was noted by Takeuchi that a decrease of two-thirds resulted in the growth of oats, when the ratio of lime to magnesia was changed from 1 to 1, to 10 to 1. The experiments of Aso, Bernadini, and Corso, and likewise of Konowalow, have indicated the proper lime- magnesia ratio for rice, wheat, rye, and barley to be Istovt For onions, Katayama found 2 of lime to 1 of magnesia the best ratio. For leaf production, in the case of mul- berry trees, Aso established the ratio of 3 of lime to 1 of magnesia. 1 Bul, Col. of Agr., Tokyo, 4, Nos. 5 and 6. 532.00 FERTILIZERS For flax, Nakamura gives the proper ratio of lime to magnesia as 1 to 1. * Experiments by Daikuhara! with a soil having 0.64 per cent of lime and 1.91 per cent of magnesia indicated that a ratio of 3 of lime to 1 of magnesia is unfavorable to beans, buckwheat, tobacco, and the cereals. The recent work by Gile gives evidence of frequent wide variations in the lime-magnesia ratios of soils, without unfavorable effects on the plants. 485. Sources of magnesia. — Magnesia is available for fertilizer purposes in several different forms : — (1) Magnesite, magnesium carbonate (MgCOs3), occurs as a native mineral in California, and elsewhere in the United States, and it is found in considerable quantities in Eu- rope. It is said to be insoluble in pure water and to be exceedingly resistant to carbonic acid. (2) Dolomite is a whitish-opaque calcium-magnesium carbonate containing about 47.6 per cent of magnesium carbonate, the remainder being carbonate of lime. (3) Magnesian limestone is one in which a part of the calcium carbonate is replaced by magnesium carbonate in proportions ranging from traces of magnesium carbonate to essentially the quantities present in dolomite. (4) Dou le manure salt (double sulfate of potash and magnesia), also referred to as low-grade sulfate of potash, and kainit. The latter contains magnesium sulfate, and also carries considerable quantities of magnesium chlorid. These salts and kieserit are considered more fully under the chapter on potash salts. 1 Bul. Expt. Sta., Tokyo, 7, No. 1 (1905) ; cited from Loew. CHAPTER XXIII SODIUM SALTS Sopium is present in the air, as sodium chlorid, in the shape of fine powder. This is derived chiefly from the winds which sweep into the air the spray of the ocean and of salt lakes. The winds also carry into the air salt dust of terrestrial origin. The quantity of common salt thus Full ration Full ration One-fourth ration Full ration sodium carbonate potassium carbonate sodium carbonate. sodium carbonate. One-fourth ration One-fourth ration potassium carbonate potassium carbonate Fic. 56.— MAnGceEts, LIMED. Fertilized alike with phosphoric acid and nitrogen. carried inland is sufficient to materially raise the chlorin content of spring and well waters in near proximity to the sea coast. : In addition to this-atmospheric source of sodium, it is a prominent constituent of many important and widely distributed minerals and rocks. 486. Mineral sources of sodium salts. — Orthoclase, one of the chief minerals of certain granites, frequently contains from 2 to 6 per cent of soda; oligoclase, also often 333 Sue eae FERTILIZERS present in granite, contains 8 per cent of soda; diorite likewise contains 3 per cent of soda; and certain volcanic rocks contain as much as 6 per cent. Thus these and other sodium-bearing minerals and rocks add, by their disin- tagvration, to the soluble sodium salts of the soil, and hence aid in their distribution throughout all arable soils. It must be borne in mind, however, that in humid regions sodium as chlorid, and also in other combinations, is being continually leached way, whereas, on the contrary, in arid regions the soluble sodium salts often accumulate to such an extent as to inhibit plant growth, or at least the growth of the usual agricultural plants. 487. Black alkali.— Chief among the noxious so- dium salts is the so-called “black alkali”? (sodium car- bonate, Na2,CO3), which was so named because of the dark color imparted to the otherwise white sodium car- bonate, by vegetable decomposition products which it dissolves. 488. Quantities of common salt injurious to crops. — The soluble sodium of soils is present chiefly as chlorid, although it may occur as nitrate, sulfate, carbonate, or silicate. In dry soils quantities of sodium chlorid as great as 1 to 1000 parts of soil are likely to be injurious to plants, though in very wet soils nearly twice that quantity may be endured. 489. The presence of soda in plants. — The presence of soda seems to be practically universal in cu:tivated plants, though the amounts in different plants vary widely accord- ing to the nature of the plant and to the condition under which it is grown. There is also a wide variation in the percentages present in different parts of the same plant. In elevated regions, very remote from the sea, the quan- tity of soda present in plants is so small that cattle reared SODIUM SALTS 335 there require much more common salt than those fed on plants grown nearer the sea. According to Pagnoul,! Peligot first pointed out the difference in the action of soda and of potash upon plants. He made analyses of many varieties of plants,? and claimed that the ash of most plants, including spinach, contained no soda, although he found it in fodder beets and in species of Atriplex and Chenopodium. When, later, Bunge * called attention to the faulty method of analysis by which much or all of the soda might have been lost, Peligot re- Full ration Full ration One-fourth ration Full ration common salt muriate of potash common salt. common salt. One-fourth ration One-fourth ration muriate of potash muriate of potash Fie. 57. — ManceEts, LIMED. Fertilized alike with phosphoric acid and nitrogen. peated some of his earlier work,* taking special precautions against the loss of soda, and again found soda absent from certain plants. It was found by Dehérain ® and Sjollema® that potato tubers were free from soda, notwithstanding that sodium 1 Ann. Agron. (1899), 467. 2 Compt. rend. (Paris), 2 (1867), 729; and in later issues of the same journal. 3 Annal. de Chemie et Pharm., 172, 16. 4 Compt. rend. (Paris), 76 (1873), 113; Abs. Centralb. f. Agr. Chem., 4 (1873), 222-226. 5 Ann. Agron., 9 (1883), 511. 6 Jour. f. Landw. (1899), 309. 336 FERTILIZERS salts were present in the manures. It is reported by Pagnoul ! likewise that potatoes grown in soil which con- tained soda were themselves free from it, and later he asserted 2 that sodium may be absent if large amounts of potash are used in the manures. He found, however, that oats absorbed soda if there was a deficiency of potash in the manures and fertilizers. That the use of sodium salts in the manures may in- crease the quantity of it in some plants is shown by Zoller, who found in the stems of beans 5.1 per cent when soda was so employed, but only 1.36 per cent when it was not. Similar wide variations were found by Wheeler and Hart- well 3 in various crops. It is reported that Coutejean and Guitteau + determined the potash and soda percentages in over. six hundred varieties of plants, and large numbers of similar deter- minations are given by Wolff. It appears that the soda content of plants may therefore vary from mere traces to high percentages. The amount found by Hilgard® in the ash of greasewood (Sarcobattus vermiculatus) was 40 per cent. 490. Sodium salts as indirect manures. — It was found by Birner and Lucanus’ that the application of sodium sulfate favored the passage of phosphoric acid into the plant and that it lowered at the same time the percentage of lime. Upon applying potassium chlorid, the ash and 1 Compt. rend. (Paris), 80 (1875), 1010; Abs. Jahresb. f. Agr. Chem., 18, 259. 2 Ann. Agron., 20 (1894), 467-479. 3 An. Rpt., R. I. Agr. Expt. Sta., 19 (1905-1906), 235-251. 4 Compt. rend. (Paris), 86 (1878), 1151-1153; Abs. Centralb. f. Agr. Chem. (1879), 259. 5 Aschen-Analysen. 6 Jahresb. f. Agr. Chem. (1892), 183. 7 Landw. Vers.-Sta., 8 (1866), 140. SODIUM SALTS BEY | dry matter of the plants were enriched in magnesia and potash, but became poorer in lime, sulfuric acid, and phos- phorie acid; and upon applying sodium chlorid a still more striking change in the same direction ensued. On the other hand, Storer! cites Dyer as authority for the statement that common salt seems to be needed to bring out the action of phosphates and nitrates, yet from ob- servations by various experimenters it would appear that there are many conditions under which common salt is Full ration Full ration One-fourth ration Full ration sodium carbonate potassium carbonate sodium carbonate. sodium carbonate . One-fourth ration One-fourth ration potassium carbonate potassium carbonate Fic. 58.— Fuar Turnips, LimMep. Fertilized alike with phosphoric acid and nitrogen. used to check the too rapid formation or assimilation of nitrates. Itis apparent, therefore, that the effect produced hinges upon the peculiar conditions which exist in any given case. It has been shown by various experimenters that upon applying calcium salts to ordinary soils, considerable amounts of potash are often rendered soluble, and the high efficiency of sodium chlorid in this respect, under exaggerated conditions, has been shown by Passarini.? Nevertheless, Miintz and Girard hold that if sodium chlorid 1 Agriculture, II (1897), 595. 2 Quorta Seine 17, Dist. la-2a; 72, della Raccolta Generale, 15. Z 338 FERTILIZERS exerts a solvent action upon soil phosphates or upon soil silicates, containing potash, it must be extremely limited. It must, however, be evident that rich potash-bearing zeolites or, possibly, glauconite would be likely to yield more potash than would be freed from feldspars ; and they would also yield considerably greater quantities of potash, if rich in that ingredient, than if they were poor in potash at the outset and were already rich in soda, lime, and magnesia. In the course of experiments with sodium chlorid and with sodium carbonate, at the experiment station of the Rhode Island State College, the serious deficiency of potash which soon developed, in a silt loam soil of granitic origin, indicated, if there had been a liberation of potash from zeolitic or other silicate combinations, that it could neither have been of very great consequence at the outset nor of long duration. In this case generous amounts of readily available phosphoric acid, as well as occasional applications in less available form, were made throughout the course of the experiments, hence it was not a question of liberation of native phosphorus compounds of the soil. Under the circumstances which existed, it was found that on both lightly and moderately limed soil, both sodium compounds showed an unmistakable tendency, in two or three different years and with several different crops, to increase the percentage of phosphorus in the dry matter of the plants.1 491. Concerning the benefit to crops from applying sodium salts. — The old and modern writers on agricul- tural chemistry and on general agriculture agree that marked benefit to farm crops often follows the application of sodium salts, though reference is commonly made to 1An. Rpt., R. I. Agr. Expt. Sta., 79 (1905-1906), 194-219. SODIUM SALTS 3839 sodium chlorid. Recently Smets and Schreiber! have pointed out that sodium salts are highly beneficial to certain plants under given conditions of field culture. Frequent ill effects from such use of sodium chlorid are nevertheless on record. It is apparent that sodium salts act more beneficially with some classes of plants than with others. From this it must be inferred that the different plants require unlike amounts of potash, which soda can liberate, that they are Full ration Full ration One-fourth ration Full ration common salt muriate of potash common salt. common salt. One-fourth ration One-fourth ration muriate of potash muriate of potash Fic. 59. — Fiat Turnips, Limep. Fertilized alike with phosphoric acid and nitrogen. unequally affected by such biological and physical changes in the soil as the use of soda may cause, or one is led to conclude that soda probably performs functions of direct physiological importance. The general recognition in Great Britain of the benefit from the application of common salt to soils is evident from the statement by Griffiths? to the effect that 250,000 tons of finely crushed common salt are used annually for ma- nurial purposes in the United Kingdom. In soils which contain calcium carbonate, it is possible 1 Récherchés sur les Engrais Potassiques et Sodiques, Maaseyck (1896). 2A Treatise on Manures (1889), 256. 340 FERTILIZERS that common salt, by its reaction with sodium chlorid, may give rise to sodium bicarbonate, which, being more basic than the carbonate of lime, may affect the chemical reaction of the soil either favorably or unfavorably ac- cording to the variety of plant involved. It has even been asserted that it may, by its solvent action, render certain humous bodies of the soil either directly assimilable by plants, or else aid in the more rapid change of some of their constituents into other available forms of plant food ingredients. It was found by Prianischnikov,! when using sodium nitrate as a source of nitrogen in the growth of plants, that the medium in which they grew became alkaline by virtue of the sodium carbonate which resulted after the removal and utilization of the nitric acid by the plants. Indeed, this isin full accord with later observation of others and with the earlier classification of sodium nitrate, by Adolf Mayer, as a physiologically alkaline fertilizer. 492. The effect of sodium salts dependent on various conditions. — That an excess of sodium carbonate in soils may be injurious, is well attested by the evil effect of the “black alkali’ (sodium carbonate) of the arid and semi- arid regions of Canada, the western part of the United States, and elsewhere. If sodium chlorid is used on an acid soil, practically devoid of carbonates of lime and mag- nesia, it may aggravate the existing condition by ulti- mately increasing the acidity, whereas on a soil where the sodium chlorid can react with carbonate of lime to form sodium bicarbonate, the reverse effect might follow. 493. The influence of sodium salts on the conservation and movement of soil moisture. — It has been shown by Ricédme? in experiments with Malcolinia maritima and 1Chem. Ztg., 66 (1900), 701. 2 Compt. rend., 137 (Paris, 1903), 141; Abs. Centralb. f. Agr. Chem., 33 (1904), 224. SODIUM SALTS 341 Alyssum maratinum that the presence of sodium chlorid in the solution outside of the plant may lessen the quantity of water absorbed, and thus protect it from an injurious degree of transpiration. The presence of the sodium salt in the plant itself was without beneficial effect in this connection, unless the existing conditions were also such as to permit of easier absorption. Since soluble salts, such as sodium chlorid, increase the surface tension of liquids, it has been pointed out by King that they may be helpful by facilitating the movement of Full ration Full ration + One-fourth ration Full ration common salt muriate of potash common salt. common salt. One-fourth ration One-fourth ration muriate of potash muriate of potash Fic. 60.— Cuicory, Limep. Fertilized alike with phosphoric acid and nitrogen. the soil water towards the surface, and hence towards the plant roots. In certain soils sodium chlorid exerts a beneficial floc- culating influence, yet in others in which the bicarbonate is readily formed, it may have the opposite effect. It is generally held by farmers that common salt added to a soil helps it to retain moisture, on which account it is helpful on light sandy soils which are readily subject to drought. This view is supported by the fact! that the presence of salts in the soil solution lessens evaporation from the surface so long as they remain in solution, and 1 King, A Textbook of the Physics of Agriculture (1901), 106, 342 FERTILIZERS in case they are separated at the surface, they then even serve the purpose of a mulch. 494. The effect of sodium salts upon osmotic pressure. — ‘here appears to be evidence that conditions may arise in which sodium salts, or other soluble salts, may be of service in connection with the growth of plants in solu- tions, merely by their increase of the osmotic pressure, though whether this would have any bearing upon the growth of plants in a normal way in soils is problematical. 495. The possible physiological and manurial functions of sodium salts. — Some writers attribute to potassium but the one function of aiding in the formation and trans- location of starch, though Benecke! indicates others, for in discussing sodium he suggests its osmotic service to the plant as a substitute for potassium. As concerns potas- sium salts, in this connection, Copeland ? has asserted that they are direct or indirect factors in maintaining turgor, also that upon the omission of salts containing phosphorus, magnesium, or sulfur, the plants, though showing poor growth, exhibited high turgor, whereas in the absence of potassium salts, the turgor was decreased and the growth stunted. Nevertheless, Pfeffer® holds that turgor is a result of conditions of growth rather than a cause of it; a view which seems to have the greater support. It is held by Pfeffer that phosphorus may be as essential as potassium in effecting the formation and translocation of starch; and as sodium often aids in carrying phosphorus to the plant, it may thus render an indirect service. It has indeed been suggested by Goodale * that sodium 1 Ber. deut. bot. Gesell., 12 (1894), Gen. Vers., 114; quoted from Copeland. 2 Bot. Gazette, 24 (1897), 411. 3 The Physiology of Plants (translated by Ewart) (1900), 1, 141, 4 Physiological Botany (1885), 255. SODIUM SALTS 343 may be substituted for a portion of the potassium required by the plant. Owing to the large quantities of sodium in certain plants, A. Mayer thinks that it may perhaps be essential or at least serviceable to them. Fic. 61. — ONIONS. With full ration of common salt. Fertilized liber- ally with nitrogen and phosphoric acid and limed. In these respects like Figs. 62 and 63. Attention has also been called by Mayer to the free movement of the salts of sodium within the plant, and he suggests that soda may just as well combine with organic acids in the plant as to have this service performed by some other base, and yet this would be without necessary 344 FERTILIZERS physiological significance. In this connection an experi- ment by Mercadante is of interest, for upon growing species of Oxalis and Rumex, without potassium, neither fruit nor flower formed, and but one-eighth the normal amount of acid was present. The oxalic and tartaric acids produced were found combined with lime, and but little starch or sugar was formed. Under normal conditions, therefore, some of the organic acids, formed during the synthesis of the proteins, are found combined with potassium. This suggests that not only potassium, but also sodium, if there is a partial lack of the former, may perform a highly useful function as a neutralizer of organic acids, and, as Mayer has suggested, it may act as a soluble conveyor of at least oxalic acid to other parts of the plant, where by contact with lime the acid is precipitated as insoluble calcium oxalate. As a re- sult the acid is prevented from reaching toxic propor- tions in certain vital parts of the plant. It was held by Salm-Horstmar! as early as 1856 that sodium was essential to wheat and oats, in connection with the perfection of the seed. From water-culture experiments with Indian corn, Stohmann? concluded that sodium was essential to its perfect development. It has been suggested by Mintz and Girard that if sodium is essential, the mangel wurzel is a plant most likely to require it. Sodium is mentioned also by Aikman, Johnson, and others, as possibly essential to plants; but if so only in very minute quantities. 496. Results by Jordan and Genter. —It was con- cluded by Jordan and Genter * that ‘soda cannot re- 1 Versuche und Resultate tiber die Nahrung d. Pflanze, 12, 27, 29, and 36. 2 Flora (1890), 207-261. 3 Bul. 192, N. Y. (Geneva) Agr. Expt. Sta., December, 1900. SODIUM SALTS 345 place potash as an active agent in the development of plant life,” or, in other words, that it could not replace it in function though taking the place of some of it in the quantity found within the plant. 497. Soda in connection with diastatic action. — An - interesting suggestion as to a possible independent phys- iological function of soda in plants has been made by Suzuki ! in which he recalls the work of Chittenden, show- ing that the efficiency of vegetable diastase is heightened by small quantities of sodium chlorid (0.24 per cent). The same has been shown by Wachsmann? to be the case with animal diastase; furthermore it has been observed by A. Mayer that a 1 per cent solution of potassium chlorid not only retarded diastatic action, but that smaller amounts exerted no decisive effect. In consequence he concludes that sodium chlorid may act indirectly, in conjunction with the diastase, in the transportation of starch to the growing tips of plants. 498. Atterberg’s experiments with soda. — An experi- ment is on record by Atterberg* in which plants were grown in quartz sand in which, in one series, calcium salts, and in another, sodium salts, were substituted for a part of the potassium, with the result that the yields fell off in the former case far more than in the latter. It has, how- ever, been learned by correspondence that it was ascer- tained later that the particular lot of sand which was used in the experiments contained surprisingly large quantities of sodium chlorid, and hence it may also have contained some potassium salts capable of being liberated by sodium salts in a greater degree than by the action of lime. This, 1 Bul. Col. of Agr., Tokyo, Imp. Univ., 6 (1905), No. 4, 408. 2 Pfliiger’s Archiv, 91 (1902), 191. 3 Deut. landw. Presse (1891), 1035. 346 FERTILIZERS therefore, throws some doubt upon whether the benefit was a direct one or was wholly or in part indirect, by virtue of the liberation of potash. The following year Wagner and. Dorsch! called attention to the manurial value of sodium salts, asserting that, in case potash was lacking, sodium was capable, in connection with certain plants, of Fic. 62. ONIONS wiITH MouRIATE oF POTASH. Full ration of muriate of potash. Fertilized lib- erally with nitrogen and phosphoric acid, and limed. In these respects like Figs. 61 and 63. increasing the crop as much as one-half. Still later Stahl- Schroeder published certain researches which seemed to him to contradict the idea that the sodium in the experi- ments by Atterberg and by Wagner and Dorsch had ex- erted a direct effect, but rather that it was indirect by virtue of the liberation of potassium. 499. The experiments at Bernburg. —In a series of 1 Die Stickstoffdiingung d. landw. Pflanzen (1892), 227-242. SODIUM SALTS 347 experiments by Hellriegel, Wilfarth, and others,! at Bern- burg, Germany, made in quartz sand or in mixtures of sand and peat, extracted previously in order to remove practically all of the available potassium, it was found that there was an increase in crops of barley and oats, when a deficiency of potash in the manures was partially made up by additions of sodium salts. There were in- dications, nevertheless, that buckwheat, potatoes, and perhaps other crops may not be benefited by sodium compounds. In discussing the work of Hellriegel and Wilfarth, Schneidewind ? calls attention to the fact that they were able, by substituting some soda for a part of the potash in the fertilizers, to produce the same amounts of sugar and of total dry matter as with the use of more potash. The latter believed, nevertheless, that the good effect of soda, which he had also observed in connection with beets, was not due to physiological functions of the sodium salts, but to the fact that the solubility of the sodium nitrate, sodium phosphate, and sodium sulfate was greater than the solubility of the corresponding potassium salts; and that on this account the several plant foods when in combination with sodium were more available. This latter conclusion is, however, open to serious question in view of the fact that Hellriegel and Wilfarth worked in pots which were watered artificially in order that optimum amounts of water might at all times be main- tained in the soil; furthermore, under ordinary soil con- ditions plants are known to make use, in a satisfactory manner, of the various potassium salts. It has been pointed out by Hartwell and Pember * 1 Arbeiten Deut. landw. Gesell., Hefts 34 and 38. 2 Jour. f. Landw. (1898), 7, 8. 3 An. Rpt., R. I: Agr. Expt. Sta., 21, 249, 250, 348 FERTILIZERS that in the experiments by Hellriegel and Wilfarth, when sodium was added, more potassium was removed in the crop than otherwise; and, furthermore, that the increase in growth was no more than might have been expected from the extra potassium thus rendered available. It was assumed by the latter investigators that when the sodium salts were deficient in the soil-culture medium, some of the potash applied in the fertilizers was fixed by the silica or otherwise, in such form that all of it could not be readily secured by the plants, but that a part of the potassium thus fixed was rendered available to a greater degree upon the addition of sodium salts. 500. The Rhode Island experiments. —It was on account of the many conflicting ideas as to the possible functional benefit of sodium salts that the matter has been studied exhaustively at the experiment station of the Rhode Island State College. At first, plants were grown in the field, in which case great benefit from common salt and from sodium carbonate resulted, when employed in connection with small applications respectively of muriate of potash and of potassium carbonate. In fact, even in cases where more than 300 pounds of muriate of potash, or its equivalent of potassium carbonate, were employed, the yields of mangel wurzels were doubled by sodium salts. In all cases heavy applications of organic nitrogen (chiefly in dried blood) and of available phosphates were made, in order to eliminate, in so far as possible, any effect of the sodium salts by way of rendering nitrogen and phos- phoric acid available to the plants. In the course of this work many different kinds of plants were analyzed in order to determine the influence of the soda upon the composition of the mineral matter! and, in some cases, 1 An. Rpt., R. I. Agr, Expt. Sta., 19, 186-316. SODIUM SALTS 349 upon the organic constituents of the plants. This work indicated that benefit from soda seemed to have resulted, in certain cases, which could not be readily explained upon the assumption that it was due to a greater liberation of potash. In order, however, to further remove doubt Fic. 63. — ONIONS. Full ration of common salt and full ration of mu- riate of potash. Fertilized liberally with nitrogen and phosphoric acid, and limed. In these respects like Figs. 61 and 62. on this point, an extensive series of water-culture experi- ments was made at the Rhode Island station by Wheeler, Hartwell, and Pember,! and by Braezeale, under condi- tions where indirect manurial action was impossible. Precautions were also taken to eliminate the possibility of benefit from the sodium salts being due to a change in 1 An. Rpt., R. I. Agr. Expt. Sta., 20 (1906-1907), 299-357 ; An. Rpt., 21 (1907-1908), 243-285. 350 FERTILIZERS the relation of the nutrients, to the chemical reaction, to the concentration of the solution, or to other similar effects, rather than to some physiological function of the sodium salt. As a result it appeared that though possibly unable to wholly replace potash in any one function, or at least in all of its functions, in connection with the growth of certain plants, sodium may and often does perform some part of one or more of the important func- tions of potassium, and thus increase the amount of dry matter which the plant can produce. 501. The practical significance of soda in agriculture. — The most practical feature connected with the utilization of sodium salts is to use for the growing of mangels, radishes, turnips, and such other crops as can make good use of them, fertilizers like nitrate of soda and kainit, which furnish nitrogen and potash; and at the same time, without added cost, supply soda. The soda, in such cases, serves as an insurance against a possible shortage of potash and may materially add to the yields. CHAPTER XXIV IRON AND MANGANESE THE importance of iron to plants has long been known, and now new interest attaches to manganese. 502. Iron in its relation to plant growth. — Experi- ments have shown that a lack of iron in plants causes pathological chlorosis, and it is believed that it may affect the protoplasmic structure in which the chlorophyl is deposited. It is therefore vital to the higher plants. The necessity of iron may be readily shown by growing Indian corn or other plants for some time in a nutritive solution, which is complete excepting for the omission of iron. After having reached an advanced stage of chlorosis, the condition can still be remedied in a very short time by the addition of ferric chlorid to the nutrient solution. Sufficient iron is present in practically all soils to meet the ordinary needs of plants. It has, nevertheless, been asserted that certain soils of northern Michigan are so deficient in this element that the plants grown upon them do not furnish sufficient iron to the cattle of the region to permit of their being brought successfully to maturity. It is stated that this can be accomplished, nevertheless, if they are supplied with fodder brought from elsewhere, or if they are removed after a time to some other section of the state. Certain salts of iron may be reduced to lower oxid com- binations under anaérobic soil conditions, or the lower 351 sy FERTILIZERS combinations may be oxidized upon draining the land or in times of drought. This latter change accounts for the frequent transformation from a bluish to a reddish brown tint observed in soils when, upon their exposure to the air, iron carbonate is oxidized to hydrous sesquioxid of iron. Where, as in muck and peat soils, the conditions are at times only partially favorable to oxidation, toxic organic compounds of the lower oxid of iron are said to result. In better aérated bogs, also, toxic iron protosulfate (FeSO, + Aq.) may be formed by the oxidation of iron sulfid (FeS,), provided the latter is present in the sands or gravels frequently used as a covering for the surface. In the latter case the toxicity can be counteracted by lim- ing, whereupon the iron salt is broken up to form gypsum, and the iron is further oxidized. Similar, but usually less striking, effects may also be noted in wet uplands. 503. Manganese in plants and soils.—It has been said that the existence of manganese in plants was first pointed out by Scheele, who found it in the ash of wild anise and of certain kinds of woods. It was later noted by Herapoth in the ash of the radish, beet, and carrot and by Salm-Horstmar in oats. é In 1872 Le Clere recognized manganese as almost universally present in soils and plants, although present in the former usually in quantities much below 1 per cent. 504. Manganese as a fertilizer.— It was found by Giglioli that manganese dioxid increased the yields of both corn and wheat. Experiments by Fukutome! have shown that the em- ployment of ferrous sulfate, in conjunction with manganese chlorid, was very helpful to flax, whereas either employed without the other had but little effect. In experiments by 1 Bul. Col. of Agr., Tokyo, 6 (1904-1905), 137. IRON AND MANGANESE 353 Garola, also with flax, it was found that the employment of salts of manganese in the manures not only increased the growth, but also the assimilation of nitrates, phos- phorus, potassium, calcium, and other ingredients. Soils that were ‘ oat-sick ’’ were restored by Sjollema and Hudig to a normal condition upon the employment of manganese sulfate. The amounts of manganese which may be safely and often profitably applied per acre, range, according to various experimenters, from nine to thirty-six pounds per acre. It is recommended that the salts be pulverized and mixed with the chemical fertilizers which are employed, or that they be mixed with the stable manure before it is applied to the land. 505. The manganese in Hawaiian soils. — Recent examinations of certain black Hawaiian soils have shown that they contain from about 4 per cent to nearly 10 per cent of manganese oxid (Mn30,), whereas the red soils of Hawaii show a range of from only 0.15 to 0.37 per cent. 506. Plants unlike in endurance of manganese. — It appears that agricultural plants are very unlike in their relation to manganese, for the quantity present in the black Hawaiian soils, although not enough to interfere with the successful growth of sugar cane, is so toxic to pineapples that the plants often fail to bear fruit. Like- wise Aso! found rice more resistant than either barley or wheat to salts of manganese, and he has also shown that its ill effects are worse in cold than in warm weather. 507. Variations in the manganese content of plants. — Manganese is very commonly present in the ash of plants, and Kelley? reports that the content of Mn,0, found 1 Bul. Col. of Agr., Tokyo, Imp. Univ., 5, 177-185. 2 The Jour. of Ind. and Eng. Chem., 1 (1909), 536. ZA 354 FERTILIZERS in the ash of pineapple leaves varied from 1.65 to 2.12 per cent, which he considers low in view of the high man- - ganese content of the soil upon which they were grown. In the ash of the bark and leaves of the Norway spruce, Schroeder found 35.5 and 41.2 per cent, respectively, of Mn;0,. The fact that so little manganese is found in some plants has led to the suggestion that possibly at certain stages of the growth of the plant it may pass back into the soil through the roots, or that it may be excreted from the aérial portions of the plants, as has been shown to be the case with certain other mineral plant constituents. 508. The effect of manganese on enzymes. — It was shown by Bertrand '! many years ago that much manganese is present in the ash of oxidizing enzymes and that certain | soluble salts of manganese increase the power to carry oxygen. In consequence, he suggested its practical trial by making application of it to the soil. The beneficial results from the use of manganese are supported also by the experiments of Loew and Sawa. The latter investigators found that manganese sulfate, in moderate quantities, was toxic to barley. It exerted a bleaching action upon the chlorophyl, and increased the intensity of the oxidase and peroxidase reactions. 509. Manganese increases many crops. — When used in very dilute solutions, manganese sulfate was found by Loew and Sawa to promote the development of the plants.? The same was found by Aso to be true of rice; and Na- gaoka? reports an increase of 37 per cent in rice, upon the application of 13.7 pounds of manganese sulfate per acre (77 kilos per hectare). A similar result is reported by 1 Compt. rend. (Paris), 124, 1032. 2 Bul..Col. Agr., Tokyo, Imp. Univ., 5, 172. 3 Ibid., 6, No. 1. IRON AND MANGANESE 355 Voelcker from Woburn (England) in experiments with wheat and other crops. In experiments by Sutherst ! it was found that small amounts of manganese compounds, including the dioxid, were helpful to maize, yet he states that Salamone found large amounts injurious. It has been shown by A. Anduard and P. Anduard that the employment of manganese increased the yields of wheat and of kidney beans, but lessened slightly the yields of carrots and of potatoes. 510. Roots change the oxidation of manganese. — In view of the alleged oxidizing power of plant roots, which it is asserted is even stimulated by salts of manganese, it is of interest to note that Kelley found the soil darker immediately about the roots of unhealthy pineapple plants than elsewhere, and that Aso discovered man- ganese dioxid adhering to the roots of wheat grown in solutions containing manganese sulfate, thus showing that the roots effect a change in the oxidation of the manga- nese. It is, however, claimed by Schreiner and Sullivan 2 that the beneficial effect of manganese is due to its pro- moting oxidation; they assert, however, that “the re- lation between oxidation and catalysis is not as clear as it should be, even in the plant where it has been exten- sively studied.” It is evident in any event that manga- nese, if employed for its alleged ‘‘ catalytic,” “stimulating,”’ or “‘ oxidizing ”’ effect, must be used very cautiously, es- pecially if the degree of sensitiveness of the particular plant under experiment is not known at the outset. 511. Manganese may aid chlorophyl development. — In growing plants by way of water-culture, it has been found that if iron is slightly deficient, the addition of a 1 The Transvaal Agr. Jour., 6, No. 23. 2 Bureau of Soils, Bul. 73, U. 8S. Dept. of Agr. (1910). 356 FERTILIZERS soluble manganese salt causes chlorophyl development and the renewed vigor that would be expected in such a case; yet, as was pointed out by Sachs! and later by Loew and Sawa, iron cannot be fully replaced by manga- nese in the production of chlorophyl. A very full review of the experiments thus far conducted with manganese is given by Giglioli and Rousset,’ and brief reference to much of the work is also made by Schreiner and Sullivan (I. c.) and others. 1 Hoffmeister, Handbuch Phys. Botanik, 4 (1865), 144; cited from Schreiner and Sullivan. 2 Ann. Sci. Agron., 2 (1909), 81. CHAPTER XXV CHLORIN, SULFUR, SILICA, CARBON DISULFID, TOLUENE, AND OTHER MISCELLANEOUS SUBSTANCES Many miscellaneous substances including iodin, bromin, boron, lithium, and others have been tested as to their influence on plant growth, but only the more important of these are considered in this chapter. 512. Chlorin.— Whereas there have been some in- stances in which chlorin has seemed to be slightly bene- ficial to plant growth, especially in connection with buck- wheat, potatoes, and possibly other plants, through some indirect action not definitely determined, it is nevertheless considered as a non-essential element. For this reason it is not classed as a plant food. 513. Sulfur. — Sulfur is essential to plant growth, and it is required in considerable amounts in the formation of certain essential oils, like those of the horseradish, cress, and for the proteins, which are present in all plants. It is, nevertheless, one of the elements supposed to be sel- dom, if ever, so deficient in soils as to require that it be supplied artificially. This is more especially the case in regions where the extended use of ready-mixed commercial fertilizers is common, since they usually contain consider- able quantities of gypsum as one of the ingredients, not only of ordinary superphosphates, but also of certain of the German potash salts. Sulfur is also added to soils in potassium sulfate, in the low and high grade sulfates of 307 358 FERTILIZERS potash, and likewise in the protein compounds of nitroge- nous organic fertilizing materials. 514. Sulfur may become depleted in soils. —It has been shown by Hart and Peterson that where farm-yard manure is applied to soils regularly and in reasonable quan- tities, the original quantity of sulfur in the soil is maintained oreven increased. Soils, on the contrary, which have been cropped for from fifty to sixty years, and which have re- ceived but little manuring, were found to have lost 40 per cent of their original sulfur, as indicated by comparisons with similar virgin soils. It has been further pointed out by Hart and Peterson that many crops remove sulfur from the soil in much greater quantities than those usually given in the tables of analyses of farm crops. This fact, however, may merely signify that a great excess of sulfur is present in the soil in assimilable form, and hence the results may serve as a more effective argument against its lack than for the ne- cessity of its application. 515. The relation of sulfur and phosphorus in plants and soils. — The fact has also been pointed out by Hart and Peterson that the amount of sulfur’trioxid represented in average crops of the grain and straw of cereals is about two-thirds as great as the amount of phosphoric acid whick these crops remove ; that in mixed meadow hay the quan- tities of the two are about equal ; and in certain legumes the amount of sulfur trioxid represented may approach, and in alfalfa even exceed, the amount of the phosphoric acid. An average crop of cabbage is said to remove from the soil the equivalent of 100 pounds per acre of sulfur trioxid, and in normal soils the amount in an acre-foot of soil was found by the method of fusion with sodium peroxid to be only from 1000 to 3000 pounds. CHLORIN AND OTHER SUBSTANCES 359 The annual addition to the soil of sulfur trioxid in the rainfall, as estimated by Hart and Peterson, for Madison, Wisconsin, is said to be from 15 to 20 pounds per acre, whereas the estimated losses by leaching, based upon the yearly drainage from the Rothamsted (England) experi- mental fields, are assumed to be about 50 pounds per annum. 516. Need of sulfur may need investigating. — In view of the preceding, and other facts, and of the attention called by Bogdanoy,! as well as by Dymond, Hughes, and Dupe ” to the possible importance of the sulfur question, Hart and Peterson believe that the possible need of an artificial supply of sulfur should be given due considera- tion in connection with future researches involving soils and fertilizers. 517. Silica in plants. — Silica is an important con- stituent of the ash of the grasses and rushes and also of many other plants. The ashes of some clovers, and of the straws of cereals, have been found to contain from 40 to 70 per cent of silica. In fact, this plant silica, by virtue of its unusual solubility, may have some heretofore un- considered value in the soil, in connection with green manuring and with the use of stable manure and straw, by way of aiding in the formation of zeolitic double salts of lime, magnesia, and the alkalies, by which the absorp- tive capacity of light soils may be advantageously in- creased. 518. Suggested functions in plants. — Silica has been supposed to serve as a protection and support in the cell walls, although not considered absolutely essential to plant growth. PTAs. Hes, hue, tls eho. 2 Jour. Agr. Sci., England, 7 (1905), 217. 360 FERTILIZERS It has been asserted by Wolff that silica favors the mi- gration of phosphoric acid from maturing stems and leaves to the seeds which are in process of development; for he secured a larger number of perfect grains in its presence than in its absence. Nevertheless, four generations of maize were grown by Jodin without silica, other than that derived from the dust of the air and from the vessels used in the experiment, but yet without apparent ill effect upon the plants. From what is now being learned about in- dividual plant peculiarities, it would, however, be unwise to conclude from experiments with maize as to the needs of all other higher plants. 519. Silica may replace other ingredients in the “ lux- ury ’’ consumption.— In experiments with oat plants Wolff determined, in the presence of an abundance of all of the other essential elements, the minimum of each which was necessary, but found nevertheless that he could not grow plants containing only these minima of all of them. In other words, there seems to be required a certain excess of mineral matter beyond such calculated minima, a part of which “luxury” need may be supplied by silica very much as sodium seems to answer a part of the general need for a soluble base when potash is present only to the extent of that minimum vital to plant growth. 520. Silica deposition checks sap diffusion. — It has been suggested by Ritthausen that silica performs a useful function through its well-regulated and gradual deposition as a gelantinous mass in the walls of cells, by which the diffusion of sap is gradually suspended, especially in the lower leaves which gradually become unnecessary and ineffective. By this process, the chief portion of the plant food contained in such leaves, together with all of the sap, is ultimately diverted to the building up of new shoots CHLORIN AND OTHER SUBSTANCES 361 and to parts of the plant which, in the later stages of growth, have become more important. 521. Carbon disulfid often increases crops. — It was pointed out by A. Girard in 1894, in connection with ex- periments extending over a number of years, that highly beneficial effects upon the growth of plants followed ap- plications to the soil of carbon disulfid, which had been used at the rate of 2904 pounds! per acre for the destruc- tion of beet nematodes. The beet crop was ruined by the treatment, but the following year the wheat crop on the treated area was much better than elsewhere. Subse- quent experiments, in which carbon disulfid was used at the same rate, resulted in a gain of from 15 to 46 per cent in the yield of wheat grain, and of from 21 to 80 per cent in wheat straw. The yield of potatoes was similarly increased by from 5 to 38 per cent, and that of beets from 18 to 29 per cent. The yield of clover was also increased by from 67 to 119 per cent. In the case of oats there was an increase in 1891 of 9 per cent in grain and of 30 per cent in straw. At Joinville, in 1892, oats showed a gain, from its use, of 100 per cent in grain and of 60 per cent in straw. 522. Reasons suggested for the benefit to soils from using carbon disulfid.— For a long time much doubt existed as to the cause of the benefit which resulted from the use of the carbon disulfid. Among the suggestions offered in explanation was one to the effect that the ma- terial might have acted as a ‘‘stimulant,” also that it might have aided by destroying certain ‘ injurious sub- terranean insects”’ or “‘ cryptogamic organisms,’’? which might otherwise exert an injurious effect upon the roots of plants. This latter view was held by C. Oberlin,? an 1 Also E. S. R., 6 (1894-1895), 564, 565. 2 Ibid., 565. 362 FERTILIZERS Alsatian viticulturist who had made similar observations on vegetables, cereals, and forage crops. It was suggested by Milton Whitney that the effect of the carbon disulfid might be due to an alteration of the physical character of the soil. It had already been established by Warrington and was supported later by J. Perraud ! that carbon disulfid checks excessive nitrification, but it was supposed that this was offset by benefit in other directions. Subsequent investigations made by P. Wagner led him to conclude that the preservative action of carbon di- sulfid on stable manure, and its beneficial action on soils, were probably due to its destruction of denitrifying or- ganisms.? 523. Treatment of soils with carbon disulfid costly. — The expense of the disulfid treatment at the time of the earlier experiments was very great. In fact, at the French price, 35 cents per pound, it cost $96 per acre, and at the prevailing American prices, due to the high tariff and other causes, the cost of treatment was $290 per acre. The use of such costly amounts of carbon disulfid simply for soil improvement was obviously not economical, but the experiments justified the belief that if but 175 to 290 pounds per acre were employed, or such quantities as were customarily applied in vineyards, that some benefit would result aside from the mere destruction of the phylloxera. 524. Carbon disulfid cures certain vetch clover and alfalfa ‘‘ sick’ soils. — Certain experiments by Oberlin ® have shown great benefit from the previous employment of carbon disulfid. He found that a soil made “ alfalfa 1Abs. E. S. R., 6 (1894-1905), 565. 2? L’Engrais, 10 (1895), No. 18, 423; Abs. E. S. R., 7, 25. 3 Jour. Agr. Prat., 59 (1895), 459-464, 499-503, 535-540. CHLORIN AND OTHER SUBSTANCES 363 sick ” by the continuous growth of the crop for six years could be effectually cured by it, at least for a time. Sim- ilar results were secured also with hairy vetch and crimson clover. It is of interest to note that, among other queries, Oberlin raised the question if the treatment destroyed all soil organisms or only certain classes of them. 525. Carbon disulfid not the only unusual compound to benefit soils. — It is impossible here to follow all of the developments in connection with sterilization by the heating of soils, likewise the use of carbon disulfid and all of the many other soil disinfectants, catalyzers, stimu- lants, indirect fertilizers, or whatever they may have been termed. Among these may be prominently mentioned toluene, tricresol, chloroform, zine sulfate, and potassium permanganate. Most, or at least many of these com- pounds are too costly to permit of their general extensive application, even though they may be highly beneficial in certain special cases, and zine compounds and certain other substances may, by their accumulation in the soil, become ultimately toxic. 526. Disinfectants, like heating, destroy soil amebe. — Recently added interest has been lent to the subject of disinfecting soils by the observations of Loew ! to the effect that soil ‘“ infusoria, flagellate, and amoebe devour great numbers of microbes.’”’ This was soon followed by the address of A. D. Hall 2 delivered at Sheffield, England, in 1910, in which he called attention to the fact that Russell and Hutchinson of the Rothamsted laboratory had found that soils which had been subjected to sterilization by chemical treatment were found to contain exceptional amounts of ammonia, sufficient, in fact, to account for their 1 Science, 317 (1910), 988. 2 [bid., 32 (1910), 363. 364 FERTILIZERS subsequent increased fertility. It was further pointed out that the sterilization was not complete, yet at the out- set it greatly lessened the number of bacteria. This was, however, but temporary, for after the soil was watered and allowed to stand, it was discovered that they had increased far in excess of the normal numbers. A given Rothamsted soil, for example, containing normally seven million bac- teria per gram, contained but four hundred after heating ; yet a few days later the number present amounted to six millions and later reached forty millions per gram of soil. Toluene treatment. — Treatment of the soil with toluene resulted similarly, and the increase in ammonia in the soil was explained by the rapid multiplication of bacteria, a conclusion suggested by the fact that their increase was coincident with this gain. The nitrifying bacteria were eliminated by the treatment, and those remaining were of the ammonifying group. This work led to the idea that the treatment had destroyed something which had pre- viously limited the bacterial development, and upon fur- ther investigation it was found to have been the protozoa which fed upon the living bacteria. - With the destruc- tion of these protozoa the ammonification of the organic matter in the soil progressed rapidly. The protozoa prob- ably concerned in the destruction of the bacteria were found to be amebe and ciliates, for they were killed by partial sterilization.! 527. Destruction of soil protozoa may explain benefit from soil ‘‘ firing’’ and deep plowing. — The preceding observations afford a probable explanation of a part of the beneficial results following the old practice of “‘ firing ” or burning soils; and also the practice of the Bombay 1 Russell, E. J., Science, 36 (1913), 520. CHLORIN AND OTHER SUBSTANCES 365 tribes, who were accustomed to burn rubbish with as much of the surface soil as possible before sowing their seed ; for such treatment would be highly destructive to protozoan life. It has since been claimed by Loew that the protozoa can probably only exist on or near the surface layers of such soils as are very compact, for the reason that the bacteria would be likely to render the store of air at the lower levels unfit for the respiration of the many proto- zoa. Nevertheless, in the Rothamsted soil, amebe are found at considerable depths. It may nevertheless be true that they exist chiefly in the surface layers of other soils. If this be true, the suggestion of Loew’s might ex- plain some part of the benefit sometimes resulting from deep plowing, as compared with a shallow working of the soil by harrowing, since the protozoa would be trans- ferred thereby to the lower levels and would possibly be largely destroyed, thus giving a better chance for the development of the beneficial bacteria and for the rapid accumulation of an abundance of quickly available nitro- gen. 528. The general applicability of soil disinfection doubted by Loew. — Notwithstanding that Loew admits the possible correctness of the conclusion of the Rotham- sted investigators, and the possibility of the usefulness of such treatment in special cases, he does not think that it will admit of general application ; furthermore, he points out the chance for the increase of possibly harmful as well as of beneficial organisms, as a result of sterilization. It is asserted, however, by Russell! that, ‘‘ The improvement in the soil is permanent ; the high bacterial numbers being kept up even for 200 days or more.” 1 Science, 37 (1913), 519. 366 FERTILIZERS 529. The chlorid of lime treatment of soil tried by Loew. — In connection with the study of a soil which had become sick for lilies, Loew made a trial of carbon disulfid, tri- cresol, potassium permanganate, and chlorid of lime. It was found that beneficial results followed the use of all of these substances, but that chlorid of lime was the most effective and the least costly of them all. Since this is perhaps the first time that chlorid of lime (bleaching powder) has ever been used for this particular purpose, it may be stated that to an area 1.5 meters long and 1 meter wide, 100 grams of chlorid of lime were applied, dissolved in 5 liters of water. A part of the solution was spread over the surface, and the remainder was poured into holes made in the soil. INDEX A. B. C. method of conserving hu- man excrement, 17. Abraumsalz, 7. Acid phosphate, definition of, 201; sometimes dyed black, 208. Acid soils yield dark extracts with ammonium hydroxid, 268. Acids, fatty, in guano, 76. Actinomycetes as decomposers of humus, 39. Aérobacter, 42. Aérobic organisms active in dung, 42. Ahlendorff & Co., 82. Ahnfeldtia plicata, 66, 231. Aikman, 344. Albinus, 165. Algee, marine, see sea-weeds. Algerian phosphates, 181, 182; composition of, 182; contain little iron and alumina, 182; good effect of, on ‘‘Hochmoor’’ soils, 182. Alkali, black, .334; is sodium car- bonate colored with vegetable matter, 334. Alsa menhaden, 88. Aluminum and iron silicates in phosphates sometimes objection- able, 221. Aluminum phosphate, 185; action of water on, 186, 188; artificial, solubility of, 186; efficiency of, increased by roasting, 185, 186; solubility of, affected by acid and alkaline solutions, 188; solubility in citric acid, 186; solubility in- creased by ammonium salts, 186; solubility in oxalic acid, 186. Alunite of little value as a fer- tilizer, 243. Amebe, destroyed by disinfectants, destroy microbes, 363. Amidase, use in treating distillery waste, 112. Amids in manure, 29. Ammonia, absorbed by soil, 30; absorbed by various substances, 31; fermentation in soils pro- moted by destroying protozoa, 363; how held in soils, 30, 31; in manure, 29; preserved by gyp- sum, 32; said to be expelled from soils by lime, 283, 284; synthetic, production of, 146; volatiliza- tion of, 20. Ammonification, method of Lipman for determining nitrogen avail- ability by, 124. Ammonite, 94. Ammonium chlorid, early use of, at Rothamsted, 7; see chlorids. Ammonium nitrate costs little for transportation per unit of nitro- gen, 146; rarely used for manu- rial purposes, 146. Ammonium salts, first employed as manures, 7; synthetic production of, 146. Ammonium sulfate, absorption of, by soils, 148, 149; aids in ren- dering certain grasses dominant, 155, 156; availability of, deter- mined by Wheeler and Hartwell, 119; appearance of, 147; com- position of, 147, 148; conditions produced by, in acid soils not equally toxic to all plants, 153, 367 368 154, 155; develops acidic condi- tions, 149; early use of, at Roth- amsted, 7; effects double decom- positions in the soil, 151; effect of, on maturity of plants, 157; efficiency of, as a fertilizer, 150; exhausts soils of lime, 149, 158; fleeting in effect, 158, 159; gives better results than nitrates in later stages of growth of some _ plants, 160; importance of the effect of, on the soil reaction, 151; impurities in, 147, 148; influence of soda in comparisons of, with nitrate of soda, 151; leaches less readily than nitrates, 159; liber- ates plant food, 158; manufac- ture of, 147; may cause injury on light calcareous soils, 159, 160; may cause partial sterility on ex- ceedingly acid soils, 152; may catse the suspension of certain bacterial activity, 157, 158; must not be mixed with certain alkaline substancés, 148; nitro- gen of, fixed by microérganisms, 149, 150; on acid soils drives out clover and certain grasses, 156; reaction of, with calcium carbo- nate, 149; reacts with zeolites, 149; results with, in Rhode Island, 152; results with, in Wo- burn, England, 152. Amylobacter, 42. Anaérobic bacteria in manure, 39. Anaérobiec organisms active in dung, 42. Anderson, 231. Anduard, A., and Anduard, P., 355 Anhydrit, 236. Antiseptics, as preservatives of manure, 34; in manure disad- vantageous, 37. Apatite, action of carbonic acid on, 178; action of water on, 178; another name for phosphorite, 175; composition of, 177, 178; distribution of, in soils, 175; oc- INDEX currence of, 177; utilization of, by process of Palmaer, 178. Aristotle, 250. Artificial basic slag meal, 198. Ascophyllum nodosum, 66, 69. Ashes, see wood, lime-kiln, cotton seed. Aso, ool, ooo, 00% Aspergillus amidase, 47. Atterberg, 140, 318, 345, 346. Atwater, 5. Aubury, 297. Available phosphoric acid, see phos- phorie acid. Azotin, 94. : Azotobacter chroococcum, 134, 135. Bacillus amylobacter, 43; arce, 47; boocopricus, 44;. erythrogenes, 45; fermentationis cellulose, 43; fluo- rescens, 42; fluorescens liquefa- ciens, 47; mesentericus ruber, 38, 42, 43; methanigenes, 43; pas- teurt freudenreichit, 45; puncta- tum, 42; suaveolens, 42; subtilis, 38; thermophilus grignoni, 38. Backhaus and Cronheim, 36, 38. Bacteria, aérobic, 38; aid ammoni- acal fermentation, 38; anaérobic in manure, 39; denitrifying, action of, on cellulose, 48; de- stroyed by protozoa, 40; increase of, accompanies increased am- monification after soil disinfec- tion and heating, 364; in manure decrease gradually, 37. Bacterial activity, effect of sulfate of ammonia on, 156, 157. Baker Island guano, 77. Barilla, 232. Barley, best lime-magnesia ratio for, 331; effect of manganese on, 354; manganese salts in moder- ate amounts toxic to, 354. Barn-yard manure, see manure. Basic cinder, see basic slag meal. Basic slag meal, artificial, 198; care in. mixing with ammonium salts and with organic nitrog- INDEX enous substances, 196, 198; con- stitution of, 194, 195; contains less free lime than earlier, 194; discovery of process for making, 8; effect of fineness of, 193; im- proves the physical condition of certain soils, 195; on clayey soils, 195; influence of silica on availability of, 192; ingredients of, 193; methods of determining the availability of, 192, 193; methods of determining free lime in, 194; not to be confused with blast furnace slag, 191; on acid pasture lands brings in clover, 196; onacid uplands action ideal, 196; on peat and muck soils, 195; other names for, 191; over- production of, in Europe,8; prac- tical use of, 195; probably not a tetracalcium phosphate, as at first supposed, 195; process of manufacture of, 191; range in composition of, 192; varies in availability, 192. Beans, best lime-magnesia ratio for, 332; kidney, effect of manganese on, 355 ; unlike as to effect of lime on, 308. Beatson, 75. Belgian phosphate, 180. Bell, see Cameron. Benecke, 342. Bergen, 231. Bergstrand, 231. Berkeland and Eyde, 8, 126. Bernadini and Corso, 331. Bertrand] 354. Beseler, 143. Bessemer process for the manufac- ture of steel, basic slag a by- product of, 8. Bird manure, see Mago and Cato. Birner and Lucanus, 336. Black alkali, see alkali. Blood, crystallized, 97; process for preparing, dried, availability of, dried, hygroscopic, 98; 3B dried, 97, 98; 98, 99; dried, 369 nitrogen availability of, 122; dried, red, chemical composition of, 97; dried, red, nitrogen con- tent of, 96; dried, red, sometimes adulterated, 96, 97. Bogdanov, 359. Bolley, 297. Bone, a favorite, with American farmers, 169; ash of, 167; black, dissolved or vitriolated, 169; chemical composition of, 166, 167, 206; disintegration of, by fermen- tation, 169; dissolved, 206; early use of, as a manure, 165; effect of steaming on nitrogen content of, 168; effect of steam- ing on, 206; effect of steaming on phosphoric acid content of, 168; gathered from battlefields, 166; organic framework of, 167; other elements in, 166,167; raw, 168; raw more available than steamed on some soils, 169; removal of fat from, 167; replaced largely at present by acid phosphate, 170; steamed, 168; treatment of, with sulfuric acid, 202; waste from industries, 168, 169; weathered, composition of, 167. Bone-black, dissolved, largely re- placed by acid phosphate, 206; treatment of with sulfuric acid, 206. Bone meal, gradually improves acid soils, 170; the reverted phosphoric acid of, 170, 171; the soluble phosphoric acid of, 170; too slow to replace lime for the correction of soil acidity, 170. Bone tankage, see tankage. Bonnet, 2. Boussingault, 3, 6, 103, 282, 311. Bradley, see Lovejoy. Braezeale, 349. Brandt, 165. Bretfield, 317. Brewer's grains, of, DVAIe Bristles, the composition of, 103. the composition 370 Brooks, 174, 241, 242. Brown, 276. Buch, 212. Buckland, 178. Buckwheat, the best lime-magnesia ratio for, 331. Bunge, 335. Burchard, 46. Cabbage, best lime-magnesia ratio for, 331. Calcium acetate, effect of, on potato scab, 301. Calcium carbide, 161; use in com- bining nitrogen, 8. Calcium carbonate, compared with burned lime, 275, 276; compared with burned lime in Pennsylvania, 275; depresses ammonification of eottaieseed meal, 285; effect of, on potato scab, 301 ; effect of, on the solubility of iron ‘phosphate in soils, 190; prevents the red- dening of blue litmus paper by fine soil particles, 270; stimu- lates the ammonification of dried blood, 285; see also limestone, ground. Calcium chlorid, effect of, on potato scab, 301; see chlorids. Calcium cymmamid, a new product, 161; changes in, taking place in the soil, 162; compares favorably with ammonium sulfate as a fer- tilizer, 163; decomposed by high steam pressure, 161; dicyanamid formed from, 163; first works for the manufacture of, 162; gradu- ally decomposes, yielding am- monia, 162; has an ultimate basic effect on soils, 163; how produced, 8; may be used in the manufacture of creatin, 163; may be used in the manufacture of urea, 163; output of, 164; process for the manufacture of, 161; sold mixed with peat, 163; toxic in its action, at the outset, 163. INDEX Calcium-magnesium ratio, effect of, on higher plants, 286; possible effect of, on nitrification of organic substances, 285. Calcium nitrate, a new fertilizer, 125; a result of cheap electricity, 125; asa carrier of lime, 128; as a fertilizer, 128; at first too hygroscopic, 127; chemical com- position of, 127, 128; conserves lime supply of soils, 128; injury to workmen and horses, in apply- ing earlier product, 128; price based on that of nitrate of soda, 129; process for making less hygroscopic, 127; process of manufacture, 126, 127; tendency in soils the opposite of ammonium sulfate, 128. Calcium oxalate, effect of on potato scab, 301. Calcium salts, like sodium chlorid, liberate potash, 338. Calcium sulfate aids the nitrification of urine, 285. Cameron, 210, 211, 251, 268; and Bell, 190, 212, 314; and Hurst, 186, 189, 214; and Seidell, 2i1, 212. Carbohydrates, destruction of, in dung, 41. Carbon disulfid, as a preservative of manures, 34; believed to pre- vent denitrification, 362; cures soils which are vetch, clover, and alfalfa, ‘‘sick,’’ 362, 363; idea of Whitney concerning, 362; not the only unusual compound to show benefit on soils, 363; often increases crops, 361; shown to check excessive nitrification, 362 ; many theories regarding action of, have been suggested, 361, 362; treatment of soils with, costly, 362; view of Oberlin concerning, 361. Carbonate of lime, carbonate ; also ground. see calcium limestone, INDEX Carbonate of potash, 241, 242; on acid soils superior to muriate, 242. Carbonate of soda, see sodium car- bonate. Carnallit, 236, 237; composition of, 237. Caro, see Frank. Carrots, effect of manganese on, 355. Castor pomace, composition of, 110; nitrogen, availability of, 122. Catalysis, as an aid in the synthetic production of ammonia, 146; re- lation between, and oxidation not yet clear, 355. Catalytic substances, 9. Cato, 1. Caustic magnesia, caustic. Cellulose, amount in manure, 41; destroyed by aérobic bacteria, 43; destruction by anaérobic organisms in manure, 43. Cereal and other seed by-products, 109, 110. ¢ Cereals, best lime-magnesia ratio for, 331. Chalk, early use of, 1. Chamber or wet acid process, 100. Chemicals and manures, factors governing the use of, 62. Chincha Island guano, 78, 83. Chinese, use of manures by, 1. Chittenden, 345. Chlor-apatite, 177. Chlorid of lime, 40; amounts of, to see magnesia, apply, 366; cured lily ‘“‘sick”’ soils, 366; treatment of soils with, by Loew, 366; mode of applying, 366; more effective and cheaper than carbon disulfid, tri- cresol, or potassium permanga- nate, 366. Chlorids, claimed by Nobbe to help buckwheat, 247; claimed by Pfeiffer to help potatoes, 247; found by Pagnoul bad for pota- toes, 247; ill effects of, due to 371 lack of carbonates, 248; ill effects of, in potassium salts, 246; Loew’s explanation of ill. effects of, 246; not good for certain crops, 246; opposing views con- cerning, 247; reasons for divers opinions concerning, 247, 248, 249 ; use of, increases the need of lime, 248; views of Griffiths as to ill effects of, 247; views of Nobbe concerning, discredited by A. Mayer, 247. Chlorin, a non-essential element, 357; occasional slight benefit claimed for, 357. Chloroform, effect of, on soils, 363. Chrondrus crispus, 66, 73, 231. Cipley, phosphates from, 181. Cladostephus verticillatus, 66, 231. Cocoons, 108; composition of, 108. Cod waste, 88. Colombian guano, 80. Comey, 327. Common crab, composition of, 92. Common salt, see salt. Compounds, definite, definition of, 250. Coniferous trees, absorbent power of needles of, 27. Cook, 242. Copeland, 255, 342. Coprolites, a term sometimes used improperly, 179; appearance of, 179; composition of, 179; dis- covery of, in England, 7; distri- bution of, 179; origin of name of, 178; sometimes of so-called con- cretionary origin, 179; where found, 178. Coquilles animalisées, 93; a mix- ture of mollusks and star-fish, 93. Corso, see Bernadini. Cotton, action of, on blue litmus paper, 268, 269. Cotton-seed hull ashes, composi- tion and use of, 229; once used largely for tobacco, 228. Cotton-seed meal, 110; tion of, 110; nitrogen, composi- avail- 372 ability of, 122; used for cotton, cobacco, and sugar cane, 110. Cotton-waste, absorbent power of, 28. Coutejean and Guitteau, 336. Coville, 281. Cow manure, see manure. Crab, see common crab. Crangon vulgaris, 91. Cress, sulfur in, 357. Cronheim, see Backhaus. Crookes, 125. Curry, see Morse. Cushman, 243. Daikuhara, 332. Dassonville, 317. Davy, 3. Dehérain, 40, 56, 58, 159, 216, 267, 280, 335; and Dupont, 48. Denitrification, an anaérobic pro- cess, 265; greater if much ma- nure is used, 58, 59; various factors affecting, 59, 60. Den treatment of phosphates, 204. De Ruyter de Wild, see Sjollema. De Sassure, 3, 7. Deutsche Landwirthschafts Gesell- schaft, 57. Devil’s apron, 66, 67. De Vries, 255. Diastatic action in manure, 42; caused by molds and actinomyce- tes, 42, 48. Dicalecium phosphate, made _ by partial acidulation of bone, 202; see also phosphate. Dietzell, 47. Dillisk, 66, 68. Diorite, amount of soda in, 334. Disinfectants, destroy soil amebe, 363. Disinfection of soils not believed by Loew to have general applica- tion, 365; claimed by Russell to have lasting effects, 365. Dissolved bone, see bone. Distillery waste wash, a source of nitrogen, 111; Effront’s process INDEX of treating, 112; industrial utili- zation of, 111; Vasseux’s process of treating, 111. Dolomite, 263, 332; of, 263% Dorsch, see Wagner. Double carbonate of potash and magnesia, analysis of, 241; to be avoided on highly magnesian soils, 241; useful on acid soils, 241. Double manure salt, see sulfate of potash, low grade. Double sulfate of potash and mag- nesia, 240, 241, 332; costs more than muriate, 240; has given good results with apple trees, 241; magnesia content of, 240, 241; to be avoided on highly mag- nesian soils, 240. Dried blood, availability of, deter- mined by Wheeler and Hartwell, 119; see also blood. Dry spot, see oats. Dihring, 41. Dulse, 66, 68. Dung, changes in non-nitrogenous matter of, 41; collecting and ecar- ing for, 20; early use of, 1; effect of feed and age of animal on, 19; terms used in discussing, 48, 49, 50; see also manure. Dupe, 359. Dupont, 38; see also Dehérain. Dusart and Pelouze, 212. Dyer, 222, 251, 337. Dymond, 359. composition Eber, W., 49. Eckenbrecher, 115. Eel-grass, 69, 231. Emmerling, 143. Enzymes, oxidizing, manganese in, 354. Eremacausis, 49. Erlwein, 129. Excrement, Bible reference to, 11; solid, amount per day, 12, 13. Excrement, human, 10; A. B. C. INDEX method of conservation of, 17; care in using, 18; conservation of by Orientals, 14; conservation of, in Paris, 14, 15; disposal of, in Europe, 13, 14, 15; number of microorganisms in, 35; Sinder- mann’s method of disposal of, 17 ; treatment with burned lime, 16, lve Eyde, see Berkeland. Farm manures, see manures. Fats, decomposition of, in manure, 44; destruction of, in dung, 41. Feathers, 103; composition of, 103. Feces, see excrement. Feldspar, of little value as a direct fertilizer, 243; shown by Hart- well and Pember to have no prac- tical value, 243, 245; value claimed for it by Cushman, 243. Felt refuse, 107; composition of, 107; use as a manure, 107. Ferments, use of, in treating dis- tillery waste, 112. Ferric phosphate, 188; solubility of artificial, in various substances, 188, 189. Feuillé, 75. Finger-and-toe disease, 299. Fish, as a source of phosphoric acid, 172; composition of, 172; needs supplementing, 91; nitrogen availability in, 122; scrap may be used without treatment, 91. Fish guano, see guano, fish. Fish scrap, acts quickly in warm, moist climates, 91; acts slowly in cold climates, 91; best on light soils, 91; value depends upon the climate and soil, 91. Fish waste, in Norway, 88; water in, 89. Flagellatze devour microbes, 363. Flax, best lime-magnesia ratio for, 332. Floats, action of manure on, 173; effect of liming on availability of, 174, 175; how to use, 174; 373 nature of, 173; soils the most useful on, 173. Florida phosphates, 183. Fluor-apatite, 177. Fluorids as preservatives of ma- nures, 34. Forchhammer, 231. Fourcroy and Vauquelin, 45. Frank and Caro, 8, 161. Frankland, 131, 159. Fraps, 186. French phosphates, 180. Frezier, 75. Fucus, see Ascophyllum . Fukutome, 352. Furuta, 331. Galdpagos guano, 80. Garbage tankage, see tankage, gar- bage. Garola, 353. Gas-house lime, see gas lime. Gas-lime, 314. Gasparin, 310, 311. Genter, see Jordan. Gerlach, 186, 189, 288. German potash salts, discovery of, in Germany, 7; impurities asso- ciated with, 7. Giglioli, 47, 352; and Rousset, 356. Gilbert, see Lawes. Gilchrist, see Thomas. Gile, 286, 302, 321, 332. Girard, 361; see Mintz. Glue, substances containing, some- times rendered less available by steaming, 106. Gluten feed, composition of, 111. Gédechens, 230, 231. Goessmann, 85, 92, 100, 107, 109 Gohn, 165. Goodale, 342. Goodwin, see Russell. Grandeau, 273, 311. Granite, amount of soda in, 334. Granitie soil, soon shows need of potash, 338. Greensand, 242; a sea-bottom de- posit, 242; composition of, 242; 374 INDEX decomposed by hydrochloric acid, 242; has value as a manure, 242; may exchange one base for an- other, 243; of possible magmatic origin, 242; proposed fusion with calcium chlorid, 243; slow in its manurial action, 242. Griffiths, 247, 339. Guanin in guano, 76. Guano, a poorly balanced manure, 83; adulteration of, 81; Baker Island, 77; Chincha Island, 78, 81; chemical composition of, 76, 77, 83; Colombian, 80; color of, 78; composition of, affected by climate, 77; distribution and sources of, 79, 80, 81; early ex- periments with, 75; early use of, 75; effect of, on physical char- acter of soil, 79; Galdpagos, 80; introduction into England, 6; introduction into Europe, 75; Ichaboe, 81; Lobos, 81; manner of using, 82; Maracaibo, 80; Mejillones, 77; nature of, 76; origin of name of, 75; Peruvian, 81; physical character of, 78; rectified or dissolved, 81. Guano, bat, appearance of, 83; chemical composition of, 84; distribution of, 84; needs sup- plementing, 85; precautions in purchasing, 84; unlike others, 83; where found, 84. Guano, fish, long used as a manure, 86; special processes for prepar- ing, 86, 87; use of, as fertilizer, 86; wastes in Japan, 87; wastes in Newfoundland, 87. Guano, horse foot, see horse-foot guano. ; Guano, phosphatic, 179, 180. Guano, whale, 89, 90; fish avail- ability of, 90; how applied, 90. Guitteau, see Coutejean. Guper, 35. Gypsum, as a renovator of black- alkali soils, 314; aids nitrifica- tion in alkaline media, 313, 314; an indirect fertilizer, 311; as a preservative of ammonia, 32, 33; as an oxidizing agent, 313; beets helped by, in Rhode Island, 310; early use of, 309; effect of, on the solubility of lime, 314; factors determining choice of, 312, 313; Gasparin’s experiments with, 310, 311; good effect of, on clover and other plants, 309, 310; holds ammonia, 313; in gas-lime, 314; liberates potash, 311; may be changed to calcium carbonate in the soil, 312; may sometimes help by furnishing sulfur, 312; methods of applying, 312; poorer than lime for acid soils, 311, 312; should be used in excess, 32, 33; sources of, 309; sources of, in soils, 309. Hair, composition of, 103. Hair, tannery, composition of, 103. Hall, 29, 60, 61, 134, 140, 154, 155, 258, 259, 286, 363. Hardy, 84. Hares and rabbits, composition of waste of, 104; waste of, 104. Hart and Peterson, 287, 358, 359. Hartwell, 328; and Pember, 173, 243, 347; also see Wheeler. Headden, 134, 135; and Sackett, 134. Heiden, 11, 13, 79, 100, 166, 277, 278. Heinrich, 122. Hellriegel, 105, 347; and Wilfarth, 5, 254, 347. Hendrick, 194. Hen manure, see manure. Herapoth, 352. High-grade sulfate of potash, see sulfate of potash, Hilgard, 31, 135, 314, 316, 324, 328, 336. Hiller, 49. Hippuric acid, 21; decomposition. of, in manure, 46. INDEX Hochmoor, see peat. Hog manure, see manure. Hoof meal, after steaming, 100; and horn meal, adulteration of, 100; composition of, 99; effi- ciency of, 100; nitrogen content of, 100; preparation of, 99. Hoof meal and horn meal mixed, 99, 100; nitrogen availability in, 122: Hopkins, 173. Horn and hoof meal, adulteration of, 100. Horn meal, 99; and hoof meal mixed, 99, 100; composition of, 99; keratin in, 99. Horse-foot guano, composition of, 92; lacking in phosphoric acid, 92; nitrogen of, highly available, 92; poor in potash, 92. Horse manure, see manure. Horseradish, sulfur in, 357. Hosius, 160. Hoyermann, 192. Hudig, 297, 353. Hughes, 359. Human excrement, 10. Humboldt, Alexander von, 75. Hurst, see Cameron. Hutchinson, see Russell. Hiittemann, W., 35. Hydrated lime, 263; becomes re- carbonated, 264; nature of, 263; production of, 263. Hydrogen, fermentation in manure, 43. Ichaboe guano, 81; composition of, 81. Ichthyosaurus, 179. Idaho phosphates, 184. Indol, 49. Infusoria, 363. Ingenhaus, 2. Insects, 108; composition of, 108. Insoluble phosphoric acid, see phos- phorie acid. Irish moss, 66, 73, 231. soil, destroy microbes, 375 Iron, carbonate, changes color on oxidizing, 352; generally present in soils in sufficient quantities, 351; higher salts of, reduced under anaérobic conditions, 351; lack of, in plants, causes chlorosis, 351 ; lower salts of, oxidized on draining, 352; need of, by plants easily demonstrated, 351; salts, toxic, broken up by liming, 352; sulfids bad in gravels or sands used as coverings for bogs, 352; vital to the higher plants, 351. Tron and aluminium silicates some- times objectionable in _ phos- phates, 221. Iron phosphate, 185, formed in soils, 188. 189, 190; James, 231. Jamieson, 247. Jenkins, 231. Jentys, 47. Jodin, 360. | Johnson, 8S. W., 102, 105, 122, 344. Joly, 210. Jordan and Genter, 344. Julie, 33. Kainit, as a preservative of manure, 34; composition of, 237. Karmrodt, 77. Karsten, 234. Katayama, 331. Kellerman and Robinson, 285. Kelley, 353, 355. Kellner, 91, 115, 120, 169. Kelp, 65, 66, 67, 231. Kette, 40. Kieserit, 332; as a preservative of manure, 34; composition of, 237. King, 257, 341. King-crab, 92. Klaproth, see Vaquelin. Knop, 6, 319, 323. Koch and Pettit, 265. Konowalo, 331. Kunkle, 165. Kuntze, 135. 376 Lachowiez, 188. Lahn phosphate, see Nassau. Laminaria digitata, 66, 67, 230. Laminaria saccharina, 65, 66, 230. Larbalétrier and Malpeaux, 318. Lawes, 75, 120; and Gilbert, 4, 5, 6, 12, 158. Leather meal, nitrogen availability in, 120, 122. Leather waste, 100; availability of, 101; improved greatly by wet acid treatment, 100; less valu- able than it appears, 102; pre- pared, composition of, 101; roasted, 101; steamed, treat- ment of, 101; treatment of, with carbonates of the alkalies, 102. Lecanu, 11. Le Clere, 352. Legumes, best lime-magnesia ratio for, 331; manurial value of, known to Varro and Columella, 1. Lehmann, 11, 160. Ley, H., 248, 328. Liebig, 3, 4, 6, 7, 79. Liernur process, for the preserva- tion of human excrement, 15. Lime, action of, on feldspar, how weakened, 288; action of, on worms and slugs, 267; aids hold- ing power of soil for bases, 289; amounts to apply, 292; analysis of burned, 262; application in Pennsylvania experiments, exces- sive, 276; as a liberator of potash, 286; beneficial effects accounted for, 307; brings in nutritious grasses and clovers, 293; by addition to clay said to form zeolites, 289; carbonate less dangerous on sandy soils than magnesian carbonate, 285; caus- tic, attacks powdered quartz, 289; cheapest basic treatment for soils, 270; chemical methods for determining need of, 270, 271; compounds transformed by plants, 295; corrects effect of excess of magnesia, 261; dolo- INDEX mitic, 263; effect of, on ammoni- fication, 262; effect of, on air cir- culation in soils, 265; effect of, on certain diseases, 262; effect of, on denitrification, 262; 265; effect of, on dry spot of oats, 297 ; effect of, on microscopic flora of soils, 262; effect of, on nitrifica- tion, 262; effect of, on nitrogen assimilation, 262; effect of, on nitrogen: availability, 264, 265; effect of, on plants as compared with gypsum, 309, 310; effect of, on potato scab, 296, 299, 301, 302; effect of, on size and yield of potatoes, 303; effect of, on soil texture, 265; effect of, on tobacco root rot, 297; effect of, on vegetable decay, 271, 272; effect of, on water, movement, 266; essential to plant growth, 261; excessive use of, to be avoided, 292; hastens crop ma- turity, 304, 305; hydrated, 263; indirect action of, illustrated, 286, 287, 289; indirect manurial action of, 286; kinds of, used in agriculture, 262, 263; knowledge of, perpetuated in monasteries, 2; lessens club-foot disease, 297; liberates phosphoric acid, 267; loses carbon dioxid in burn- ing, 262; losses of, from soils, by leaching, 289, 290; magne- sian, 263; may cause injury to pineapples, 302; may improve light soils physically, 266; mis- cellaneous sources of, 264; needed for some plants, but bad for others, 306; not required to extent shown by some methods, 271; occurrence of, 261; oxalate of, changed into carbonate in soils, 295; oxalate of, in plants, 295; potash fixed after liberation by, 287, 288; practical applica- tion of, 292, 298; precipitated out in the plant as calcium oxa- late, 330; pure, compared with INDEX magnesian, 293, 294; require- ments of different plants for, 307, 308; should usually be intro- duced into the soil, 293; slaked, becomes quickly carbonated, 277, 278; slaked, highly beneficial in Rhode Island, 276, 277; some- times excreted from plants as earbonate, 330; treatment of excrement with, 16; use of, in connection with phosphates, 266, 267; use of, on mossy land, 293; use of, on pastures, 293; waste, from industries, 314, 315; where to spread, on the surface, 293. Lime, builders, see burned lime. Lime, burned, see burned lime. Lime-magnesia, ratios best for barley, 331; beans, 332; buck- wheat, 331; cabbages, 331; cereals, 331; flax, 332; legumes, 331; maize, 331; mulberry leaves, 331; oats, 331; rice, 331; tobacco, 332; wheat, 331. Lime-nitrogen, 161. Lime, slaked, avoidance of use of, to conserve humus not always wise, 273, 274, 275; compared with calcium carbonate and marl, 278, 289, 280; earlier believed not to carbonate quickly, 277, 278; effect of, on potato scab, 301; errors of Heiden concern- ing, 277, 278; if used properly, does not injure soils, 275; in- creases nitrogen content of humus, 272, 273; good results from, 276, 277; rotations of crops essential in connection with use of, 273. Lime, slaked and burned, concern- ing their expulsion of ammonia from soils, 282, 283; influence of, on nitrification, 283, 284, 285; in- troduction of, into acid peat sub- soils, 281; large amounts of slaked lime check nitrification, 284; penetration of, into soils, 280, 281, 282; views of European authorities concerning, 280. 377 Lime and magnesia, percentage of, in crops and relation of, to yields, 329, 330. Lime-kiln 228. Lime-magnesia ratio found by Gile to vary widely without ill effects, Soe. Lime rock, see burned lime. Limestone, see burned lime. Limestone, burned, 263; changes produced in, by burning, 262; composition of, 263; distribu- tion of, 261; dolomitic, 263; effect of, on soils, 261. Limestone, coarse, compared with fine limestone, 290, 291; com- pared with marl, 290, 291. Limestone, magnesian, 332. Liming, need of, suggested by soil acidity, 268. Limulus Americanus, 92. Linseed meal, composition of, 110; nitrogen availability in, 122. Lipman, 124, 285, 286. Liquors, dark, in leachings of dung, SZ. List, 36. Litmus paper, action of cotton on, 268; action of finely divided material on, 268, 269; reliability of, questioned, 268, 269. Litter, absorbent power of different kinds of, for water and ammonia, 27, 31; ammonification of, 47; amounts of, to use, 26, 27; as an absorbent, 26; conserving power of, 28; cotton waste as, 28; in- fluence of, on manure, 19; leaves as, 27; micro6érganisms in, 36; mosses as, 27; needles of conif- erous trees as, 27; oat straw as, 27; pea straw as, 27; peat as, 27, 31; sawdust as, 27, 31; soil as, 27, 31; spent tan as, 27; wheat straw as, 27. Lobos guano, 83, 179; composition of, 179. Lobster refuse, 92; composition of, 92 ashes, composition of, 378 Loew, O., 246, 253, 285, 286, 294, 316, 319, 321, 322, 323, 325, 330, 363, 366; and Sawa, 354, 356. Loges, 143. Lovejoy and Bradley, 126. Lucanus, see Birner. Lupines, varying effect of lime on, 308. © Macrocystis purifera, 74. Maercker, 143, 157; and Schneide- wind, 30. Magnesia, a carrier of phosphorus in the plant, 316; aids in the translocation of starch, 316; and lime ratios in the soil, 321, 322, 323; conflicting ideas concerning the action of, 317, 318, 319; essential to plant growth, 317; functions of, in the plant, 316, 317; in Japanese soils, 321, 322; in Ohio soils, 322; lime ratio, method of determining, in soils, 323; quantities in different parts of plants, 323; sources of, for fertilizer purposes, 332; theory _ of Loew concerning, 319, 320, 321. Magnesia, caustic, danger in using for a time, 324; gave good results the second year, 324; toxic at first, 326. ' Magnesia and lime in relation to yields, 329, 330. Magnesian lime, more dangerous on light than on heavy soils, 327; possible danger in using, 326, 327; precautions in use of, 294. Magnesian limestone, 332. Magnesite, 332. Magnesium carbonate, aids am- monification of cotton-seed meal, 285; artificial, more soluble in carbonated water than calcium carbonate, 327; depresses am- monification of dried blood, 285; may cause injury by its alkaline action, 327; natural, highly in- soluble, 328; newly “ormed, a INDEX quicker corrective of acidity than dolomite or magnesite, 328, 329: solubility of artificial, 329; solu- bility of natural, 327, 328. Magnesium chlorid, concerning the alleged toxic action of, 323; ex- cessive amounts of, injurious, 323; not always poisonous, 324, 325; studies of, by Wheeler and Hartwell, 324, 325, 326. Magnesium fluor-apatite, 178; see Wagnerite. Mago, 1. Maize, best lime-magnesia ratio for, 331; effect of manganese on, 355. Malpeaux, see Larbalétrier. Malt sprouts, composition of, 110. Manganese, amounts of, safe to use per acre, 353; beneficial effects of, may be due to promoting oxidation, 355; cannot fully re- place iron in plant nutrition, 355, 356; change in oxidation of, caused by roots, 355; dioxid found adhering to roots, 355; effect of, on carrots, 355; effect of, on kidney beans, 355; effect of, on potatoes, 355; effect of, on wheat, 355; exerts bleaching action on chlorophyl, 354; help- ful to -maize, only in small amounts, 355; in Hawaiian soils, 353; in plants studied by Le Clere, 352; increases oxidase and peroxidase reactions, 354 ; in- creases yields of corn and wheat, 352; may aid chlorophyl develop- ment, 355, 356; noted in plants by Herapoth, 352; plants unlike in endurance of, 353; presence of, in plants shown by Scheele, 352; promotes development of plants grown in dilute solutions, 354; restores ‘‘oat-sick’’ soils, 353; review of experiments with, in plant nutrition, 356; salts of, increased growth of flax, 352, 353; salts must be used cau- * INDEX tiously, 355; wide variations in amount of, in plants and soils, 353, 354. Mangon, M. Hervé, 72. Manure, amids in, 29; ammonia in, 29; amount of cellulose in, 41; amount of pentosans in, 41; amount of starch in, 41; anti- septics disadvantageous as pre- servatives of, 37; barn-yard, 19; denitrification in, aided by certain substances, 57, 58; denitrifica- tion in, greater if used abun- dantly, 58, 59; effect of chloro- form on, 40; effect of heating on, 40; effect of, on potato scab, 301 ; farm, 19; farm animals often kept on, 29; favors disintegra- tion of old sod, 63, 64; immediate incorporation of, with soil desir- able, 56; importance of strep- tococci in, 37; influence of litter on, 19; lacks effectiveness when fresh, 52; lasting qualities of, 60, 61; liquid, preservation of, 53; losses of, in heaps and _ broad- casted,: 56, 57; losses from, in- creased by bacteria from intes- tinal tract, 51; losses from, less in later stages of decomposition, 51, 52; losses from, lessened, when moist and compact, 50, 51; losses from, lessened by packing and trampling, 28; losses of sugar in, 41; molds in, 39; nature and cause of losses occur- ring in, 50; necessity of moisture in, 53; practical utilization of, 55; reason for even spreading of, 63; stable, 19; storage of, versus direct application of, 55, 56; supplemented profitably by chem- ical fertilizers, 61, 62; time to spread, 57; treatment of, in Europe, 53; types of micro- organisms in, 37: use of coarse, 62, 63; waste of, by “‘fire- fanging’’ and _ otherwise, 20; yeasts in, 39. 379 ’ Manure, cow, adapted to certain greenhouse plants, 22; amount of, produced per cow, 23; chemi- cal composition of, 22; number of micro6rganisms in, 35; often improved by mixing with horse manure, 22. Manure, hen and pigeon, composi- tion of, 25; need supplementing, 26; of superior value, 25; solid and liquid of, voided together, 26; rich in nitrogen, 26. Manure, hog, amount of, produced per animal, 25; composition and value of, 24. Manure, horse, annual production of, per animal, 22; composition of, 21; ferments readily, 20, 21; litter used with, 21, 22; losses of, by ‘‘fire-fanging,’’ 20, 28; methods of storage of, 22; num- ber of microérganisms in, 35. Manures and chemicals, factors governing use of, 62. Manure, solid, ammonification of, 47. Manure salts, 237, 332. Manure, sheep, amount of, pro- duced per animal, 24; composi- tion of, 24; value of, 23. Maracaibo guano, 80. Marchand, 230, 231, 234. Margraff, 165. Marl, comparison of a low grade of, with slaked lime, magnesia, and oyster-shell lime, 279, 280; com- pared with coarse and fine lime- stone, 290, 291, 292; early use Olyel- Maturity of plants, effect of am- monium sulfate on, 157. Matzuschita, 36. Mayer, A., 139, 160, 246, 247, 340, 348, 344, 345. McFarland, 74. Meat meal, Australian, 94; avail- ability of, 95; composition of, 94, 95; little available for direct use, 95, 380 Mejillones Island guano, 77, 80; availability of nitrogen of, 122. Menhaden, handling of, 88, 89; nitrogen content of, 89; phos- phoric acid content. of, 89; treatment of, with acid renders phosphoric acid and _ nitrogen available, 89; waste, treatment of, with acid, 89. Mercadente, 255, 344. Methane, fermentation in manure, 43. Meyer, D., 318, 321, 323. Microc. uree liquefaciens, 46. Microorganisms, absent in urine, 36; in litter, 36; in manure, sig- nificance of, 36; number of, in dung, 35; types of, in manure, 37, 38. Miller, 41. Millot, 211. Mineral elements, prime importance of, shown by Lawes and Gilbert, 6. Mineral theory of Liebig, 3, 4. Miquel, 46. Molds in manure, 39. Molon, Ch. de, 86, 87. Monocalcium phosphate, see phos- phate. Montana, phosphates of, 184. Morse and Curry, 286, 287. Moss, absorbent power of, 27, 31; Irish, 66, 73, 232. Mosselmann, 16. Muck and peat, as soil amend- ments, 109; composition of, 109; especially valuable on light soils, 109; origin and nature of, 109. Muds, improve sandy and gravelly soils, 109; salt and fresh, 109; too poor to haul far, 109. Mulder, 316. Miiller, A., 16; 45. Miller-Schir, 16. Munro, 247. Miintz, and Girard, 28, 30, 31, 33, 123, 337, 344; and Gaudechon, 2ote INDEX Muriate of potash, compared with sulfate of potash, 249; composi- tion of, 237, 240; impurities in, 240; safer if rainfall is heavy and lime is used, 249. Murray, 100, 167. Myxomycetes in manure, 39. Nagaoka, 354. Naidace, 65. Nakamura, 332. Napoleon, 14. Nassau, or lahn phosphate, 180. Navassa phosphate, 185. Nepheline, of value as a fertilizer if finely ground, 243; less valuable than German potash salts, 243. Night soil, a danger to health, 10, 11; conservation of, 10; name for human excrement, 10. Niter, see potassium nitrate. Nitrate of ammonia, see ammonium nitrate. Nitrate of soda, amounts to use per acre, 137; availability of, 137; availability of, as determined by Wheeler and Hartwell, 119, 120; care in using, 137; composition of, 136; conserves the lime supply of the soil, 143; corrects acidity, 139; early classed by A. Mayer as physiologically alkaline, 340; effects of, on soil micro- organisms, 145; first exploited, 135; hygroscopic action of, 142, 143; improves certain soils physically, 141, 142; impurities in, 136; increase in output of, 136 ; injures some soils physically, 142; introduction of, into Eng- land, 6; is physiologically basic, 139; may conserve the potash in soils, 141; may liberate potash, 140; may partially re- place potash in plant production, 140; methods for the purifica- tion of, 136; nitrogen avail- ability of, 122; not a stimulant, 143, 144; physical characteris- INDEX 381 tics of, 137; residual effects of, guano, 122; in distillery slop, 139, 140; residual soda of, a dried, 121; in dried blood, 119, carrier of phosphoric acid to the 122; im dried fish, 122; in farm plant, 143; should not be applied in too large amounts at a time, 113; sources of, 132; theories regarding the origin of, 133; yields quick returns, 145; yields sodium carbonate in the soil, 139. Nitrate of potash, see potassium nitrate. Nitrification, method for determin- ing nitrogen availability by rate of, 123; temperature favorable to, 130. Nitrogen, amount of, in coal, 147; Atwater’s work on assimilation of, 5; assimilation of, studies by Hellriegel and Wilfarth, 5; at- mospheric, method of combining, 8; combined, dependence of many plants on, 5; early theories regarding, 3, 4; fixation of, by electricity, 126, 129, 161, 162; large applications at the outset in certain forms not always best, 113: Nitrogen availability, an abundance of other needed _ ingredients should be used when determin- ing, 114; as determined by Hein- rich, 122; as determined by S. W. Johnson, 122; as determined by Seyffert, 122; as determined by Wagner and Dorsch, 119; determinations of, necessitate the use of different amounts of nitro- gen, 114; determinations of, by Eckenbrecher, 115; determina- tions of, by Kellner, 115, 120,121; determinations of, by Petermann, 115, 116; determinations of, by Voorhees, 120; erroneous deduc- tions in determinations of, 115, 116; in blood meal, 121; in bone meal, 119, 121; in bone meal, steamed, 121, 122; in castor pomace, 122; in cotton-seed meal, 122; in crude Mejillones manure, 121; in fish-scrap, 121; in green plants, 119, 121; in hoof and horn meal, 122; in horn meal, 119, 121; in leather meal, steamed, 122; in leather waste, 119; in linseed meal, 122; in meat meal, 119; in night soil, 121; in nitrate of soda, 119, 122; in Peruvian guano, 121; in press cake, 121; in rape cake, 121; in raw bone meal, 121; in rice husks, 121; in stable manure, 119; in sulfate of ammonia, 119, 121; in tankage, 122; rules of Wagner and Dorsch for deter- minings. 216; si7, + 118; 219. properly based on the nitrogen taken up by the plant, 114; view of Lawes concerning, 120. Nitrolim, 161: Nitrolime, 161. Nobbe, 247. Noll, see Strasburger. Norway spruce, see spruce. Nothnagel, 36. Oat straw, absorbent power of, 27. Oats, best lime-magnesia ratio for, 331; dry spot of, 297; effect of lime on, 297. Oberlin, C., 361, 362, 363. Oidium lactis, 39. Oils, essential; sulfur aids in for- mation of, 357. Oligoclase, amount of soda in, 333, 334. Omelianski, 43. Orth, 280. Orthoclase, amount of soda in, 333. Oxalates in guano, 79. Oxalie acid, effect of, on potato scab, 301; in guano, 76. Oxygen, discovery of, 2. Oyster-shell lime, burned and un- burned compared with stone lime, marl, and magnesia, 279, 280. 382 ’ Pagnoul, 247, 335, 336. Palissy, 2. Palmaer, 178. Palmaer phosphate, 199; a dical- cium phosphate, 199; experi- ments with, in Sweden, 199; in- ferior to basic slag meal for peat soils, 200; on sandy and peat soils the immediate and residual effects of, equal those of super- phosphate, 199; process of manu- facture of, 199; solubility of, in ammonium citrate, 199. Passarini, 319, 337. Pasteur, 45, 49. Payen, 16; and Boussingault, 103. Pea straw, absorbent power of, 27. Pearl ash, see potassium carbonate. Peat, absorbent power of, 27, 31; see muck. Peat soils, failure of lime to pene- trate, 281. Pectin, decomposition of, in manure, 43. Peligot, 335. Pelouze, see Dusart. Pember, see Hartwell, see Wheeler. Penicillium glaucum, 47. Pentosans, amounts of, in manure, 41. Pepsin method for determining nitrogen availability, 123. Permanganate method for deter- mining nitrogen availability, 123. Permanganate of potash, see potas- sium permanganate. Perraud, J., 362. Peruvian guano, 81. Petermann, 105, 115, 226. Peterson, C., 99; see Hart. Petlitt, 86. Pettit, see Koch. Pfeffer, 255, 342. Pfeiffer, Th., 247. Phonolite, of value as a fertilizer if finely ground, 243; less valuable than the German potash salts, 243. INDEX Phosphates, artificial, from low- grade phosphates, 200; artificial, by bisulfate treatment, 201; artificial, from aluminum phos- phate, 201; choice of, affected by the soil and crop, 225, 226, 227; den treatment of, 204; of Belgium, 180; of France, 180; of Idaho, 184; of iron and alu- minum, 185, 186, 188, 189, 190; of Montana, 184; of Northern Africa, 181; of Portugal, 181; of Russia, 181; of Tennessee, 184; of the islands of the Pacific, 180; of the Western States, 184; of Western States favorably situ- ‘ated, 185; of Wyoming, 184; other artificial, 200; Palmaer, 199; relationship of the various, 203 ; Wiborgh, 198 ; Wolter’s, 199. Phosphate, acid, see acid phos- phate. Phosphate, dicalcium; action of water on, 211, 212; action of, water on, increased by carbonic acid, 212. Phosphate, monocalecium; action of water on, 208, 210, 211; help from liming after certain rever- sions of, 216; reversion of, 215; reversion of, with iron and alu- minum oxids often serious, 219, 220; sometimes highly bene- ficial, 219. Phosphate, tricalcium; action of water on, 212, 218, 214; action of water on, increased by car- bonie acid, 213; oxids of alu- minum and iron in, are objec- tionable for superphosphate manufacture, 219; solubility and decomposibility of, increased by certain substances, 214. Phosphates of Florida, black river pebble, 1838; bowlder, 183; com- position of, 183; land pebble, 183; rock, 183. Phosphates of South Carolina, age of, 182; nodular, 182; of lime- INDEX stone origin, 182; river, 182, 183. Phosphatic guanos, 179, 180. Phosphoric acid, free; definition of term, 202; preparation of, from tricalcium phosphate, 202. Phosphoric acid, insoluble, 218. Phosphoric acid, reverted; avail- ability of, 217, 218; insoluble in water, 217; not all from dical- cium phosphate, 217. Phosphoric acid, soluble; advan- tages of, 215; after fixation may be highly available to plants, 223; determination of, 214, 215; reversion of, 216. Phosphorite, see apatite. Phosphorus, discovery of, 165; found in bones, 165; found in pyromorphite, 165; from phos- phoric acid, 165; from seeds of mustard and cress, 165; in apa- tite, 165. Phyllophora membranifolia, 66, 231. Pigeon manure, see manure. Pineapple, manganese in, 354. Pineapple chlorosis, caused by lime, 303; cured by applying iron salts to the leaves, 302. Pine sawdust, power of, to absorb ammonia, 31. Plant nutrition, first experiments Aipeas Plants, miscellaneous, lime on, 307, 308. Pogys, see Menhaden. Polyhalit, 236. , Polyides rotundus, 66, 231. effect of Pomace, castor, composition of, 110. Pond-weed family, 65. Popp, 243. Portuguese phosphates, 180. Potash, absorption of, in soils, may have several causes, 250, 251; contracts with American fertilizer manufactures, 235; deposits, oc- currence, and distribution of salts of, 235; deposits of salts of, in 383 | Germany, 234, 235, 236, 237; factors affecting absorption of, 251, 252, 253; fixed in soil after liberation by lime, 287, 288; geo- logical age of deposits of salts of, 236; history of the German salts of, 234, 235; in ash of, Indian corn cobs, 233; in potassium car- bonate, 233 ; in potassium nitrate, 233; in sea-weeds, 66, 230, 231; in soils, replaces other bases, 250; in tobacco stems, 232; little loss of, by leaching, 251; mines bought by Americans, 235; retention of, by soils, 250; see potassium and _ potassium salts. Potassium, aids: carbohydrate for- mation, 253; as a neutralizer and carrier in the plant, 255; cannot be fully replaced by sodium, 253; conserved in the soil by sodium salts, 260; defi- ciency of, more serious for some crops than for others, 259, 260; degree of replacement of, by sodium depends upon the kind of plant, 253; effect of a lack of, on plants, 258; effect of an absence of, on Oxalis and Rumex, 344; effect of, on photosyn- thesis, 254; effect of, on turgor, 255; essential to plant growth, 253; in alunite, 243; in feldspar, 243; in greensand, 242, 243; in leucite, 248; in nepheline, 243; in phonolite, 243; increases the size of grain and amount of crop of cereals, 254; increases the leg- umes in mixed herbage, 258; good effect of, on legumes, 257, - 258; lessens vapor pressure in soils with beneficial effect, 254; may contribute a part to the ‘luxury consumption” of the plant, 256; may improve or in- jure the physical condition of the soil, 257; may increase surface tension, 256, 257; may lessen 384 evaporation, 257; may stimulate nitrogen assimilation by increas- ing carbohydrates within the plant, 258; necessary to combine with organic acids, 344; not the sole cure for clover sickness, 258; permanganate, effect of, on soils, 363; salts act best in wet seasons, 259; silicate, 241; vari- ous functions of, 253. Potassium carbonate, 241, 242; sources of, 233; the chief im- purities of, 233; valuable for certain soils, 234. Potassium chlorid, see muriate of potash. Potassium magnesium carbonate, 241; good for acid soils, 241. Potassium nitrate, as an incrusta- tion on some soils, 129; composi- tion of, 130; impurities of, 131; made artificially from nitrate of soda, 131; made in artificial niter beds; 130; manurial value known by the year 1669, 6; often economical as a fertilizer, 131, 233; sources of, 129, 130; special uses of, 233; use of, per- mits the avoidance of chlorin, isale Potassium salts, alleged ill effects of chlorin of, 246, 247; German, duration of deposition of, 238; natural deposits of, elsewhere than in Germany, 238; removed from soil less readily than salts of sodium, 246; tabulated analy- ses of, 237. Potassium sulfate, composition of, 237; fate of, in soil, 249; high grade, 240; low grade, 240, 241; reduced under anaérobic condi- tions, 249. Potatoes, effect of manganese on, 355; size and yields of, increased by liming, 303, 304. Potato scab, cause of, 299; effect of barn-yard manure on, 301; effect of calcium oxalate on, 301; INDEX effect of calcium chlorid on, 301; effect of calcium sulfate on, 301; effect of oxalic acid on, 301; effect of slaked lime on, 301; effect of sodium carbonate on, 301; effect of wood ashes on, 301; fungus lives saprophytically in the soil, 301. Prianischnikov, 340. Priestley, 2. Proteins, sulfur in, 357. Protozoa, according to Loew can- not exist at the lower soil levels, 365; destroy bacteria, 40; de- stroyed by certain substances, 40; destruction of, may explain the benefit observed from firing soils, 364; found at considerable depths at Rothamsted, 365; may destroy bacteria, 39; may explain part of the gain from deep plowing, 364, 365. Pugh, 4. Putrefaction, 49. Pyridin or other similar compounds have been found in soot, 108. Pyrite in phosphates for superphos- phate manufacture objectionable, 22. Quiros, Allier & Co., 75. Rabbits, see hares. Raleigh, Lord, 125. Redonda phosphate, 185. Reed, 282, 316. Reese, Jacob, 8. Rémy, 173. Reuter, see Treadwell. Reversion of phosphates, reactions in course of, described, 218, 219, 220, 221. Reverted phosphoric acid, see phos- phoric acid, reverted. Rhodymenia palmata, 66, 68, 230. Rice, best lime-magnesia ratio for, 331. Ricéme, 340. Ritthausen, 360. INDEX Robinson, see Kellerman. Rossi, 129. ; Rousset, see Giglioli. Russell, and Goodwin, Hutchison, 40, 363. Rye, best lime-magnesia ratio for, 331. 29; and Sachs, 356. Sackett, see Headden. ' Salamone, 355. Salfeld, 70. Salm-Horstmar, 344. Salt, common, 236; amount of, in- jurious to crops, 334; large amounts of, used in Great Britain, 339; may indirectly cause solu- tion of vegetable matter, 340; reacting with calcium carbonate may produce sodium carbonates, 340. Saltpeter, see potassium nitrate. Saltpeter waste, composition of, 229; should be bought on analy- sis, 229. Salts, neutral, check dissociation, 328. Salzthon, 236. Sawa, see Loew. Sawdust, absorbent power of, 27, 31. Schacke, 243. Scheele, 165, 352. Schellmann, 47. Schenck, see Strasburger. Schneider, 186. Schneidewind, 347; see Maercker. Schreiber, see Smets. Schreiner and Sullivan, 355, 356. Schroeder, 354. Schucht, 220. Schultz, of Lupitz, 70, 248. Sea weeds, analyses of, 66, 230, 231; as affecting the need of lime, 72; barilla from, 232; chemical com- position of, 66, 230, 231; com- pared with farm-yard manure, 72; composition of, at different seasons, 67, 68; composting of, 385 73; effect of, on quality of crops, 70, 71; especial attention called to, as a source of potash by the famous German-American potash contracts, 229; free from weed seeds, 72; may injure hops, to- bacco, and beets for sugar, 71; not well balanced as a manure, 72; of chief importance in New England, 68; often improved by leaching, 71; often preferable to stable manure, 70; of the Atlan- tic coast, 66, 230, 231; of the Pacific coast, 74, 232; potash in, 66, 229, 2380, 231; practical utilization of, 70; produce smooth potatoes, 70; quick in their action, 71; rapidity of growth of, 74; size of, 74; use in Europe, 66; value of, known to the ancients, 65; value of, limited by cost of handling, 69, 70. Sennebier, 2. Severin, 33, 38, 40. Seyffert, 122. Sheep manure, see manure. Shimper, 255, 317. Shoddy, composition of, 107; im- proves the physical condition of some soils, 107; use of, as a manure, 107. Shrimps, as a fertilizer, 91; ing in phosphorie acid, 91. Siemens and Halske, 129. Silene orientalis, 307. Silica, an important constituent of plants, 359; content of, in the - ash of plants sometimes 40 to 70 per cent, 359; deposition of, checks sap diffusion, 360; may favor migration of phosphoric acid to the seed, 360; may have special value for plants, 359 ; may help form zeolites in soils, 359; may help some plants but not others, 360; may replace other ingredients of plants in their ‘luxury consumption,” 360; may lack- 386 support and protect the cell wall, 359; not found by Jodin to be essential to plants, 360. Silicate of potash, a valuable fer- tilizer, 241; analysis of, 241; manufacture of, discontinued, 241; results with, in Massachu- setts, 241. Silk waste, nitrogen in, 104. Sindermann, 17. Sjollema, 335, 353; and De Ruyter de Wild, 41. Skatol, 49. Skinner, 75. Slugs, see worms. Smets and Schreiber, 339. Societéa Generale per la Cianamide, 162. Soda, absorbed by oats if potash is deficient, 336; as an indirect manure, 336; claimed to be sometimes absent in plants, 335; content of, in plants widely vari- able, 336; favors passage of phos- phoric acid into plants, 336; in feldspar, 333; liberates magnesia, 337; presence of, in higher plants practically universal, 334, 335; said to be absent from potato tubers, 335; universally distrib- uted in nature, 334; used in the fertilizers may increase’ the amount in the plant, 336; see sodium, and sodium salts. Sodium, claimed by some to have acted only indirectly, 346; claimed to help by being a highly soluble carrier of nitrogen and phosphorus to the plant, 347; concluded by Stohmann to be essential to perfect plant develop- ment, 344; conclusions of Jor- dan and Genter concerning, 344, 345; if essential to plants, minute quantities of, suffice, 344; in- creased crops one half when po- tassium was lacking, 346; may partly replace potassium as a combining and carrying agent in INDEX the plant, 344; potassium re- placed better by, than by eal- cium, 345; see soda, and sodium salts. Sodium carbonate, a residual prod- uct from the application of nitrate of ‘soda to soils, 340; effect of, on potato seab, 301. Sodium chlorid, amounts of, in- jurious to crops, 334; an indirect manure, 337; effect of, on potato scab, 301; if it causes the for- mation of carbonates, it may de- flocculate soils, 341; in the air, 333; liberates potash, 337, 338; seems to bring out the action of phosphates and nitrates, 337; sometimes aids by flocculating soils, 341; sources of, in the air, BB ae Sodium nitrate, see nitrate of soda. Sodium perchlorate, as an impurity in nitrate of soda, 136, 137. Sodium salts, benefit from, not always explained by liberation of potash, 349; benefit to crops from applying, 338, 339, 340; certain plants apparently not benefited by, 347; doubled the yield of mangel wurzels, 348; effect of, dependent on various conditions, 340, 341; effect of, on osmotic pressure, 342; experi- ments of Atterberg with, 345; experiments with, in Rhode Island, 348, 349, 350; facilitates movement of water toward the surface of the soil, 341; favor diastatic action, 345; frequently injurious, 339; increase phos- phorus percentages in the plant, 338; increase surface tension. 341; indirect manurial action of, impossible in water culture, 349; in the experiments of Hellriegel and Wilfarth, liberated potash, 348; in the plant, protect from too rapid transpiration, 341; in water culture helpful, 349; may INDEX * lessen evaporation, 341; mineral sources of, 333, 334; more bene- ficial to some plants than to others, 339; of benefit to plants in the field, 348; outside the plant may lessen the water ab- sorbed, 341; possible manurial function of, 342; possible physio- logical functions of, 342; prac- tical significance of, in agriculture, 350; precautions in connection with use of, in water culture, 349, 350; substitution of, for a part of the potash in certain functions of plants, 342, 348; see soda, and sodium. Soft phosphate, composition of, 184. Sdhngen, 45. Soil, absorbent power of, 27, 31; as an absorbent of ammonia, 30. Soil disinfection, good effects of, endure long, 365; may not be generally applicable, 365. Solid solution, definition of, 250. Soluble phosphoric acid, see phos- phoric acid, soluble. Solution, solid, see solid solution. Sombrero phosphate, 185. Somme phosphates, 181. Soot, benefits soils physically, 108; chemical composition of, 108; light, is best, 108; nature of, 107; often rich in ammonia, 107; rarely toxic, 108. South Carolina phosphates, 182. Spent tan, absorbent power of, 27. Spruce, Norway, manganese in, 354. Stable manure, see manure. Stahl-Schroeder, 346. Star-fish, composition of, 92, 93. Stauf, 147. Stead, 195. Stockhardt, 289, 318. Stohmann, 6, 344. Stoklasa, 35, 41. Storer, 92, 243, 267, 271, 288, 310, 319, 337- 387 Strasburger, 36; Noll, Schenck, and Shimper, 317. Stutzer, 150, 318. Sulfate of ammonia, see ammonium sulfate. Sulfate of potash, see potassium sulfate. Sulfate of potash, high grade, 240; low grade, 237, 240. Sulfate of potash and magnesia, Zot. Sulfur, amount of, in hay and legumes, 358; carried in the rain- - fall, 359; essential to plant growth, 357; important in essen- tial oils, 357; in cress, 357; in certain German potash salts, 357; in gypsum, 357; in horse- radish, 357; in proteins, 357; in superphosphate, 357; losses of, by leaching at Rothamsted, 359; may perhaps become depleted in soils, 358; relation of, to phos- phorus in the plant and soil, 358; amounts of, removed by cabbages, 358; removed from soils in large amounts by some crops, 358; re- moved to the extent of 40 per cent from soils long cropped, 358; returned to soils in farm-yard manures, 358; should be further investigated, 359 ; supposed to be seldom if ever deficient in soils, Sone Sulfurie acid, as a preservative of manure, 34. : Sullivan, see Schreiner. Superphosphate, aids maturity and starch production in potatoes, 227; asa preservative of manure, 33; best adapted to what crops, 226, 227; care in the manufac- ture of, 203, 204; double, cheap to transport, 205; double, 37, 204, 205, 206; double, manufac- ture of, 205; especially adapted to the top-dressing of grass and grain, 226; especially helpful, with other ingredients, for sugar 388 beets, 227; fixation chiefly in surface soil, 222; fixation of, in soils rapid, 221, 222; flocculat- ing action of, 225; free phos- phorie acid in, 202; injury from, rare, 223 ; made from various sub- stances, 201; manufacture begun by Lawes in the year 1842, 7; may give inferior results on cer- tain soils, 225; preparation of, 201, 202, 204. Superphosphatgyps, 37. Sutherst, 355. Suzuki, 345. Sylvanit, 236, 237; composition of, 237, 239. Tacke, 243. Takeuchi, 331. Tangle, 65, 66, 67, 230. Tankage, availability of nitrogen in, 122. Tankage, bone, as a fertilizer, 96; composition of, 96, 172; method of employment of, 96; nature of, 95; value of nitrogen of, 96. Tannery hair, composition of, 103. Tennant, 319. Tennessee phosphate, 184. Teuthorn, 17. Thaer, 3. Thaxter, 299, 301. Thiel, C., 104. Thielavia basicola, 297. Thiocyanates as an impurity in ' ammonium sulfate, 147. Thomas and Gilchrist, 191. Thomas meal, see basic slag meal. Thomas phosphate, see basic slag meal. Thomas phosphate basic slag meal. Thon, 17. Thurneyssen, 87. Tobacco, best lime-magnesia ratio for pale Tobacco stems, potash in, 232. Toluene, 40; effect of, on soils, 363. powder, see INDEX Toluene treatment of soils, de- stroys protozoa, 364; increases ammonification, 364; results of, 364. Treadwell and Reuter, 327. Tricalcium phosphate, see phos- phate. Tricresol, 40; effect of, on soils, 363. Tull, Jethro, 2. Turgor, effect of potassium on, 255. Ullao, 75. Ullmann, 247. Urea, 29, 163; decomposition of, in manure, 44, 45, 46. Urie acid, decomposition of, manure, 47; in guano, 76. Urine, amount of, produced per per- son, 11; human, chemical com- position of, 11, 12; microérgan- isms essentially absent from, 36; nitrification of, aided by calcium sulfate, 285. Urobacillus duclauxii, 46. Urobacillus jakschii, 46. Urobacillus pasteuri, 45. in Van Senus, 43. Vauquelin and Klaproth, 165; see Fourcroy. Vega, Garcilaso de la, 75. Viard, 211. Vibrans, 230, 231. Ville, 4, 317, 319. Virgil, 1. Vivianite, an iron phosphate, 188. Voelcker, 139, 152, 158, 159, 251, 355. Von Feilitzen, H., 200, 243. Von Freudenreich, 35. Von Raumer, E., 316, 319. Von Wagner, L., 246, 328. Von Wolff, E., 316. Voorhees, 92, 100, 120. Wachsmann, 345. Wagner, 95, 120, 140, 157, 362; and Dorsch, 116, 119, 148, 150, 152, 157, 346. INDEX 389 Wagnerite, 178. Wilfarth, 4, 105, 260, 347; see Warrington, 131, 313, 362. Hellriegel. Water-slaked lime, see hydrated | Wolff, 336, 360. lime. Wolter’s phosphate, process of Wavellite, an iron phosphate, 185. manufacture of, 199; solubility Waxes and fats, decomposition of, in manure, 44. ' Way, 250. ; Weiser and Zaitschek, 41. Western phosphates, 184. Whale, fat difficult to separate, 90; glue sometimes used as a ferti- lizer, 90; guano, 90. Whale-bone, composition of, 90. Whale waste, 88 ; composition of, 89. Wheat, best lime-magnesia ratio for, 331; effect of manganese on, aDo: Wheat straw, absorbent power of, Diol Wheeler and Hartwell, 4, 67, 105, 119, 230, 231, 232, 247, 256, 260; 324, 329, 336; Hartwell and Pember, 349. Whitney, M., 362. Wiborgh phosphate, constitution of, 198; now superseded by Palmaer phosphate, 199. of, in citric acid, 199. Wood ashes, composition of, 228. Wool, composition of, 103. Wool, waste, as a manure, 104; composition. of, 104; effect of superheated steam on, 104; Petermann’s test of availabil- ity of, possible errors in, 105; soluble, not lost by leaching, 105. Worms and slugs, action of lime on, 267, 268. Wurtz, 243. Wiitrich and Von Freudenreich, 35. Wyoming, phosphates of, 184. Yeasts in manure, 39. Zaitschek, see Weiser. Zoller, 336. Zostera marina, 65, 69, 231. ive following pages contain advertisements of a few of the Macmillan books on kindred subjects SOILS THEIR FORMATION, PROPERTIES, COMPOSITION, AND RELATIONS TO CLIMATE AND PLANT GROWTH IN THE HUMID AND ARID REGIONS By E. W. Hilgard, Ph.D., LL.D. Professor of Agriculture in the University of California, and Director of the California Agriculture Experiment Station. Cloth, 8vo, 593 pages, $4.00 net This work, originally designed as a text-book for the writer’s University classes in agriculture, has been considerably expanded in response to a wide- spread demand for a book which should present the principles and practices of agriculture, not only in connection with the humid regions as has mostly been done in existing works, but equally so in respect to the arid regions. The important and often critical differences between the soil conditions of the two regions and of the corresponding differences in practice are only casually referred to in most existing works. This painful gap in agricultural literature Dr. Hilgard fills upon the basis of a prolonged personal experience both in the humid and arid regions of the United States, In order to adapt the volume to popular as well as professional readers the - text is printed in two different kinds of type. The larger contains the matter which is essential to any intelligent student of the subject and which will be found interesting by any farmer or man with a country place. In the smaller type is contained the more strictly scientific and technical matter. “Dr. Hilgard, by reason of his special and long-continued attention to the chemistry of soils, and his intimate acquaintance with the subject, was pecu- liarly well fitted for the task to which he applied himself in the preparation of the present work. 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After such principles are found, they need to be tested by use in reorganizing farms. “The conclusions in this book are based on investigations of the kind given above, and on cost accounts, census data, travel and study in differ- ent parts of the United States and experience in farming. It is hoped that the conclusions may be of use to farmers and students.” — Preface. THE MACMILLAN COMPANY Publishers 64-66 Fifth Avenue New York Corn Crops By E. G. MONTGOMERY, Professor of Farm Crops in the © College of Agriculture at Cornell University Preparing This is a text-book on corn and the sorghum crops, including the grain sorghums, the sweet sorghums for syrup or forage, and the — broom corns. In it plant structures, physiology, and the other technical phases of the subject are separated from the more practical phases which might be classed as cultural methods. Hence, the entire book is adapted to use as a text in an advanced course, and the treatment of cultural methods is adapted to use in more elementary courses. The book is also an excellent handbook for farmers and others interested in the production or handling of corn or sorghums. Crops and Methods for Soil Improvement By ALVA AGEE Illustrated, cloth, r2mo, $1.25 net; postpaid, $1.38 A simple and comprehensive treatment of all questions bearing on the conserving and improving of farm soil. The book is not a technical treatise, being designed solely to point out the plain, every-day facts in the natural scheme of making and keeping soils productive. It is concerned with the crops, methods, and fertilizers that favor the soil. The work will be of interest to the practical man, the farmer, the lecturer, and all who deal directly or indirectly with farmers, and because of its popular style, it is easy reading for any one. 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