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phosphoric acid with little or no nitrogen; and bone, bat-guano, and Peruvian guano, which contain considerable nitrogen with their phosphoric acid.

Potash.-The chief supply of potash in fertilizers is found in the German potash-salts, of which there are several grades, the most important being the sulphates, muriates, and kainite. PRESENT SOURCES, CHARACTER, AND PROSPECTIVE SUPPLY OF COMMERCIAL FERTILIZERS. -A few facts concerning the mode of occurrence, character, and prospects of future supply of some of the more important commercial fertilizers may not be out of place. For a number of statements here given we are indebted to an article on "Commercial Fertilizers: Sources of Supply and History of the Trade," by Dr. E. H. Jenkins, in the Report of the Connecticut Board of Agriculture for 1881.

Nitrogenous Fertilizers: Nitrate of Soda.In Northern Chili, formerly Southern Peru, in the province of Tarapacá, between the Andes and the ocean, is a vast arid plain of tableland, three thousand feet above sea-level, stretching north and south for eighty miles. The winds that blow steadily from the Andes make an absolutely dry climate. The soil is destitute of vegetation, and the territory is uninhabited. On this plain occur vast deposits of nitrate of soda. It lies in strata five hundred yards wide and seven or eight feet thick, and in hollows looking like dried-up lakes, whose sides are coated and bottoms covered with the nitrate underlying common salt. The origin of the deposits is undetermined. It is conjectured that the nitrogen first came from guano deposits on the shores of an inland salt lake or sea, that through atmospheric agency it was oxidized to nitric acid and then replaced chlorine in the salt of the lake, and on evaporation was left in its present shape. The crude nitrate of soda is purified at the coast by solution, separation from sand, and recrystallization, and shipped to Europe and the United States. "In 1820 the first cargo was sent to England, but was thrown overboard in harbor because the duty was so high that it would not pay to pass it through the custom-house. In 1830 a cargo came to the United States, but found no sale. In that year 18,700 tons were exported from Iquique; in 1840, 227,300 tons; in 1850, 511,800 tons; in 1860, 1,370,200 tons; in 1870, 2,743,400 tons. In 1872 the amount had risen to 4,000,000 tons, and in the following year the Peruvian Government took the matter into its own hands and decided to export only 4,500,000 tons annually, so as to keep the price constant. At present the region is in the hands of the Chilian Government, and is likely to remain there.

"Till now only one grade of nitrate of soda has appeared in our market, and that has never shown any fluctuation in composition, running from 94 to 96 per cent of pure nitrate of soda, with from 1 to 1 per cent of salt, 2 per cent of water, and a very little insoluble matter."

Sulphate of Ammonia.-Another source of nitrogen is found in ammonia salts, particularly the sulphate of ammonia, which is now chiefly obtained as a by-product in the gasmanufacture. When of fair quality it should contain from 16.5 to 20 per cent of nitrogen, or from 777 to 94 per cent of the pure salt. Formerly our supply came mostly from England, but of late it is being manufactured largely in this country. It is stated that lowgrade sulphate of ammonia, with only 7 to 8 per cent of nitrogen, is being imported here. Such ammonia salts are apt to contain sulphocyanide of ammonia, a substance rich in nitrogen but poisonous to plants.

Animal Refuse: Dried Blood, Meat-Scrap, etc.-Another very important source of nitrogen for fertilizers is the offal of slaughterhouses, which comes into the market under a variety of forms and names: as, dried blood, meat-scrap, azotin, ammonite, tankage, etc. In the smaller slaughter-houses, the old way of letting the offal run to waste still prevails, but in the large establishments of both the East and West, scarcely a pound of the solid matter of the animals is left unutilized.

The blood is drawn into tanks, the albumen is coagulated and separated, the remaining solid residue is dried by various methods, and sold as dried blood, with from 9 to 12 per cent of nitrogen. It is a cheap, efficient, and valuable source of this costly element. Tankage and meat-scrap are names applied to the refuse flesh and viscera, with often more or less bone, prepared by processes similar to those used for dried blood. They are rich in nitrogen, and contain considerable phosphoric acid also. Ammonite or azotin is prepared from beef and pork "cracklings," the refuse from tallow and lard melting, by extracting them with benzine.

Fish-Scrap-Fish-Guano.-One of the most important sources of nitrogen for fertilizers in this country is the refuse left after the extraction of oil from fish, especially the menhaden. The early settlers of Massachusetts and Virginia learned from the Indians to manure their corn with fish, and it has long been the practice of farmers on the Atlantic coast to spread menhaden on their land for a fertilizer. Since the menhaden began to be utilized for the extraction of oil, a cognate industry has been developed in the manufacture of a concentrated fertilizer from the residual "pomace" or "scrap." The first successful attempt to manufacture a fertilizer from fish-scrap is credited to a Mr. Lewis, of New Haven, Connecticut, in 1849. The fish were steamed or boiled until disintegrated, pressed to remove the oil, and the presscake dried and ground. This is essentially the process now employed, though more or less successful modifications have been devised, especially to secure more complete extraction of oil, which is a valuable commodity when separated, but detrimental in the fertilizer. The crude material is known as fish-scrap. When dried and pulverized it is called fish-guano.

The present extent of this industry and the use made of fish-manures may be gathered from the fact that, in 1875, the nitrogen derived from fish-manures was equal to that contained in 80,000 tons of Peruvian guano. In 1880 there were 79 fish-factories on the Atlantic coast, employing 443 vessels and 3,200 men; 2,035,000 gallons of fish-oil were produced, and 45,000 tons of scrap. The various kinds of animal refuse, dried blood, tankings, fish-scrap, etc., are used chiefly for "ammoniating" superphosphates.

Peruvian Guano.-This wonderful material, whose use by millions of tons has done so much to restore fertility to the depleted soils of Europe and America, has been in the past the most important of the various commercial fertilizing materials. Peruvian guano, as is well known, consists mainly of the excrement of birds, which has been accumulating for centuries on the almost rainless coasts and adjacent islands of Peru and Chili. What makes the excrement of birds particularly valuable as a fertilizer is that the excretion of both kidney and intestines is mixed in the cloaca, and voided in a comparatively solid condition. What makes guano so far superior to any fresh manure of the kind is that the sole diet of these birds was fish, which are rich in phosphoric acid and nitrogen, and also that all the moisture was speedily taken out of the mass by the dry, hot winds continually passing over it. It is interesting to note that our lands are continually suffering a loss in nitrogen and other elements of plant-food which, through various channels, finds its way continually to the ocean and passes out of our reach; and that through the agency of these birds many million tons of these same elements have been recovered from the ocean, and stored up where of all places they would keep best for our use, long before we felt the loss and desired its replacement. The use of guano as a fertilizer dates back at least to the time of the Incas in the twelfth century. The old Peruvians had a proverb to this effect:

"Guano can work miracles,

Though it is not numbered with the saints." Humboldt brought samples to Europe, the analyses of which were published in 1806. A more complete investigation was made by Liebig and Wöhler in 1837. In 1840 a shipload was brought to England, and since then many million tons have been taken to Europe and to this country. Of late the supplies of Peruvian guano have been curtailed and unreliable, partly because of the exhaustion of some of the deposits, and partly because of the misgovernment and war in Peru. The future of the Peruvian guano supply it is impossible to forecast. The supply for the coming year is said to be assured, and it is the opinion of those in position to judge, that, with a stable and enlightened government, Peru may supply Europe and America with guano for years to

come.

Phosphatic Guanos and Rock Phosphates.— Peruvian guano being little exposed to rain, has retained a large portion of its soluble constituents. Many of the bird deposits, however, are subject to more or less frequent rains, which either wash back into the ocean the freely soluble materials, or bring them into reaction with the coral limestone by which they are in part retained. As a rule, the nitrogen and potash are lost, while the phosphates are retained and become a valuable source of phosphoric acid, forming what are called the phosphatic guanos. In former years we received a great deal of this material from some small Pacific islands of coral formation under the name of American guano. In 1856 the United States assumed the protection of all the guano islands in the Pacific which lay within 10° of the equator north and south, and between longitude 150° and 180°. The islands chiefly worked were Baker's, Howland's, and Jarvis's. The guano was brown, pulverulent, and coarse-grained, and could be shoveled without picks. It contained from thirty to forty per cent of phosphoric acid, and by treatment with sulphuric acid made excellent superphosphates. For some time past, however, the whole product has been carried to Europe. Our main supply of this material comes now from the West Indies. Just at the mouth of the Gulf of Venezuela, in the Caribbean Sea, lie Great Curaçoa and Little Curaçoa Islands. For some years they have furnished large quantities of guano to Germany and the United States. The Little Curaçoa guano from which most of our supply comes is poorer in phosphoric acid than the other, averaging from twenty-five to twenty-eight per cent. Its mechanical condition, however, is better. Great Curaçoa guano goes largely to Germany. It is hard and rocky, but has from thirty-eight to forty-two per cent of phosphoric acid. Another phosphatic guano, which has been used to considerable extent in this country, is the Orchilla, which has a somewhat similar composition, though it is of rather inferior value and importance. Another rock phosphate from the West Indies, the Navassa, is now extensively used in this country as material for the superphosphate manufacture. The phosphatic deposits of Navassa Island were formed under water and thrown up by volcanic action. The phosphate is inferior to the phosphatic guano mentioned, especially because of a large content of iron and alumina, which causes superphosphates made from it to "revert" badly.

South Carolina Phosphates.-Dr. Jenkins, in the article already referred to, speaks of this as follows: "The South Carolina phosphate beds I believe are, and for some time will be, the chief source of raw material for our domestic superphosphate manufacture.

"For most of the facts given in this connection I am indebted to an interesting printed report by Professor C. U. Shepard, Jr., of

Charleston, who has had a more extensive experience in the matter than any one else, and to verbal information received from him. As to the real extent of the deposits which can be worked to advantage, we at present are not fully informed, for the industry is still in its infancy. The existence of vast beds of phosphorite was known before the war, but they were not worked till after its close. This material is found in many places on and near the sea-coast, but the larger part hitherto mar keted has come from the region lying to the north and northwest of Charleston between the Cooper and Stono Rivers, and from the region at the head of St. Helena Sound on the Bull and Coosaw Rivers northeast of Beaufort. "It is essentially a phosphate of lime soft enough to be got out with shovel and pick. The land deposits occur in a stratum from six to fifteen inches thick, though averaging not more than eight inches, and where worked do not lie more than six feet below the surface.

"There are also submarine deposits consisting both of loose material brought down by the current, and of fine regular strata. This is known in the market as river rock.'

"The rock is always washed, drained, and dried somewhat before shipment, and some firms dry their material thoroughly by piling it up under cover around tubes which are supplied with hot air. Hot-air dried cargoes at present make up more than half the total amount shipped.

"The extent of the industry is indicated by the following figures:

"There were shipped from Beaufort and Charleston the following amounts of crude phosphate: In 1875, 122,790 pounds; 1876, 132,626; 1877, 163,220; 1878, 210,323; 1879, 199,365; 1880, 190,763; 1881, 266,734."

Apatite. Very large deposits of the mineral apatite have been opened in Canada, and are being utilized for the manufacture of superphosphate. It is said, however, that the bulk goes to England, the market rates being at present such as to make other materials, as South Carolina phosphates, cheaper for our home use. The apatite, however, makes an excellent fertilizer, and the supplies are, fortunately, very extensive.

Bone-Manures.-Of these, the most important are bone, raw, boiled, and steamed, boneblack, and bone-ash. Bone is offered to the farmer almost everywhere and in a great variety of forms, and is, perhaps, more widely used than any other concentrated manure. Raw bones contain from 3 to 4 per cent of nitrogen, and from 20 to 25 per cent of phosphoric acid. Steamed bone is generally a little poorer in nitrogen and richer in phosphoric acid, while bone which has passed through the glue-factories contains often but a small fraction of one per cent of nitrogen, and may run as high as 30 per cent of phosphoric acid. Bonemanures vary in mechanical condition as well as in composition. Very fine-ground bone

acts quickly, but coarsely ground bone, especially if greasy, is one of the slowest of fertilizers to decompose in the soil and furnish its material to the plant. Adulterations of bone with intent to defraud are not frequent. A great quantity of very coarse bone is used, but boiling and steaming, which remove the fat and make the bone friable and easily ground, is becoming very general, and the result is a great improvement in the quality of bone-manures. The spent bone-black from sugar-refineries furnishes a small but constant supply of material, not suited for direct application to land, but much prized as a basis for superphosphate because of its fineness and convenience for treatment with sulphuric acid. Even when genuine bone-black is out of the market, manufacturers bent on satisfying their customers continue to turn out this popular superphosphate by a judicious mixing of mineral superphosphates and lamp-black. Bone-ash from South America is occasionally found in the markets.

Potash and the German Potash Salts. The question whence the potash for the depleted soils of the world was to come, was for years a serious one with chemists and agriculturists. Wood-ashes were a very limited and withal costly source, and did not supply enough for use in manufactures and other than agricultural arts. The extraction of potash from orthoclase feldspar and from sea-water, though feasible, was too costly. The solution of the difficulty was found a few years ago in the discovery of the potash deposits in the region of Stassfurt, in Germany. This accumulation of salts has come from the evaporation of sea-water in past geologic time. The process of evaporation, whose cost, when carried on by artificial means, would be so great, has been provided for by nature on an enormous scale, and we have the products in the deposits referred to. Commencing near there but a few years ago, the use of potash salts as fertilizers has already become almost universal in Germany, has extended largely into other parts of Europe, has reached to the impoverished fields of our own country, and even to the coffee-plantations of Brazil and Ceylon. The amount used has increased from a few hundred to many thousand tons per year. The Stassfurt fertilizers have excited an interest and reached an importance comparable with that to which Peruvian guano attained years ago. The results of a great deal of experimenting and experience indicate that the usefulness of these salts as fertilizers depends not only upon the character of the salts themselves, of which there are various grades, but also on the kind of soil, the mode of application, and the kind of crop. Properly used on soils deficient in potash, they are extremely beneficial and profitable. A singular fact in connection with the Stassfurt mines is that the potash compounds were at first thrown away. The mines had been opened for the sake of the salt, of which they supply immense quantities. On the layer

of salt there rested enormous beds of saline compounds known to contain a great deal of magnesia and some potash. To get at the salt below, these magnesia and potash salts had to be dug out and dumped on waste land at the mouth of the mine. In 1860 the chemist Rose called attention to the waste, and the government encouraged fertilizing experiments with a view of utilizing this material, and also offered premiums to manufacturers who should devise methods of producing high-grade potash salts from them. In both directions there was complete success. The extent to which the industry has grown may be illustrated by a few figures. The amount of high-grade salts produced has been, according to the best data at hand, in 1862 about 3,000 tons; in 1863, 9,000 tons; 1864, 21,500; 1865, 14,700; 1866, 26,782; 1867, 25,991, while from this time the production increased until in 1877 it The Composition of Various Sorts of Commercial Fertilizers, Farm Manures, and other Fertilizing Materials.

reached 106,809 tons. Besides these highgrade materials, very large quantities of inferior grades are sold. The bulk of the potash salts in our markets belong to three classes Sulphates, Muriates, and Kainite. The sulphates are difficult of preparation, costly, and sometimes contain less sulphate of potash than represented. The muriates are rarely below grade, and are for general uses the cheapest and most desirable. The kainite is a lowgrade salt containing a small percentage of potash, and a large amount of common salt and magnesium compounds.

A most useful and satisfactory exhibit of the composition of the commercial fertilizers in our markets is given in a tabular statement, compiled from the most reliable analyses, by Dr. Jenkins, in "The Farmer's Annual HandBook for 1882,"* from which we condense the following:

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Perhaps the most interesting phase of the late history of commercial fertilizers is the experimental study of their action upon the soil and influence upon the growth of plants. A large number of agricultural colleges, experiment stations, bureaus, societies, and private individuals have been lately engaged in this work, and results of great value are being attained. Experiments in Georgia: Composts.-The Department of Agriculture of Georgia, under direction of J. T. Henderson, commissioner, has continued, during the season of 1881, the soil-tests of commercial fertilizers, which it has been conducting for some years past. In these experiments various brands of superphosphates, guanos, etc., alone and composted with cotton-seed or stable-manure, have been applied by planters throughout the State to parallel strips of land, on which various crops, especially cotton, were grown. The results are, on the whole, very encouraging for the use of high-grade fertilizers, though failures are not infrequent, even with favorable weather.

The very rational plan of composting concentrated fertilizers, such as acid phosphates with cotton seed and farm manures, has brought most gratifying results. Thus one of the experimenters, Professor W. M. Brownę,

of the State University at Athens, says: "My experience and observation, during the past five seasons, convince me that we can not afford to raise crops on upland without the aid of commercial fertilizers of established reputation, and of composts carefully made." Another experimenter, Mr. E. S. Wellons, of Perry, Houston County, says: "My experience, particularly on my own farm this season, more clearly than ever demonstrates the wisdom of composting acid phosphate with cotton-seed and stable-manure."

Experiments in Alabama: Fertilizers for Cotton. Professor W. C. Stubbs, of the Agricultural and Mechanical College of Alabama, who has been conducting extensive series of experiments with fertilizers for cotton, arrives at a number of very interesting conclusions, of which several may be briefly stated, as follows:

1. The soils upon which the experiments were made, and which result from the decomposition of metamorphic rocks, principally hornblendic and feldspathic, appear to need no potash, little nitrogen, and a great deal of soluble phosphoric acid. Indeed, one great want which seems to prevail throughout the older cotton States (except, perhaps, in individual regions, such as the black cretaceous prairie cotton-belt of Alabama, which has not been tested) is soluble phosphoric acid. On wornout soils a small quantity of nitrogen is also required-three parts of nitrogen to ten of phosphoric acid being a good mixture, as shown by experiments.

2. Phosphoric acid hastens, and nitrogen retards, the maturing of the plant.

3. Cotton-seed or cotton-seed meal is as efficacious as, and a far more economical source of nitrogen than, the much costlier guano, animal refuse, nitrate of soda, and other commercial materials. These conclusions are borne out by carefully conducted experiments as well as by large experience.

The doctrine that the Southern States will do better to utilize nitrogen in a home product than import it at an expense of millions of dollars every year is certainly an important one. Fortunately, it is getting to be understood and followed.

During the past five years several hundred field experiments with fertilizers have been conducted in concert in all the States east, and some west, of the Mississippi, and the provinces of Canada, by farmers, schools, and experiment stations. The results of a large num

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