grade the cheaper the available phosphoric acid per pound, and the lower the grade the higher its price. In fact this rule holds good with all kinds of fertilizer supplies.

26. The total shipments of South Carolina rock from ports in South Carolina and by rail, during the past ten years, has been as follows:

27. In 1884 one of our most careful staticians estimated the total consumption of commercial fertilizers in the United States, as follows:

28. The potash of commercial fertilizers is usually obtained either from the sulphate or the muriate of potash; it is least expensive in the former form and is therefore mainly obtained from either the natural or artificial sulphate.

29. Dr. Marcker, of one of the German Experiment stations draws the following conclusions after a long series of experiments with potash salts on various crops:

30. "Failure in the use of potash salts is very often due to a lack of phosphoric acid and nitrogen in the soil. A direct action of potash salts is only expected on such soils as are naturally deficient in potash, especially light porous soils.

31. Since by absorption in the soil all potash salts pass into combination with silica, it is of no consequence as far as supplying a deficiency of potash is concerned, whether muriate or sulphate is used. Frequently the cheapest form of potash is the best."

32. "There is no reason to believe that potash salts which contain chlorine are injurious to vegetation; on the contrary, the muriate is often to be preferred because its potash is more thoroughly diffused through the soil. Potatoes and sugar beets, however, are an exception to this rule, since starch or sugar production is decreased by the muriate; tobacco is also injured as to burning quality by the same.

33. "The impure (low grade) potash salts have indirect effects as follows: 1. They act as solvents on the plant food held in the soil. 2. They keep the soil more moist. 3. They tend to make summer grain ripen earlier."

34. German potash salts (kainit), being a natural production, is very liable to vary much in quality and the amount of actual potash which it contains. During the past few years this variation has been greater than formerly. This variation is due to the want of care (or possibly with a direct intent to deceive) in digging the product from the mines. 35. Of the two forms, Dr. Goessmann of Massachusetts, writes as follows: "The sulphate of potash is unanimously indorsed as the safest potash compound, without regard to kind of crop, and as far as the quality of some industrial products are concerned. It increases the percentage of starch in potatoes and of sugar in beets. It counteracts best, and in common with nitrate of potassa, the tendency of tobacco

to char and to smell offensively, thereby rendering it better adapted to smoking and increasing its commercial value. Upon wet lands alone it is considered unprofitable and the chloride of potassium is considered the safer article."

36. The percentage of potash in unleached wood ashes varies with the kind of wood from which it is made, being highest in hard woods and lowest in soft ones.

37. In many cases farmers are paying too high prices for wood ashes as a source of potash and would find it much more economical to purchase and use high grade potash salts (commercial), and this is especially true where freight and hauling is an object and important item. 38. The higher grade of potash salts are made from the lower ones. by the removal of other material (mostly common salt) by inexpensive processes which leave the increased potash at a less cost per pound to the consumer. In cases where the cost per pound is not actually reduced the saving in freight and handling will still make them the most economical source of potash.

39. As to the time at which applications of potash should be made, Goessmann writes: "The experience of German experimenters tends to prove that, as a general rule, the most satisfactory results are obtained by incorporating the potash salts into the soil during the autumn; only in case of a light and sandy soil, which at the same time is quite free from lime and magnesia, do they advise their application in the early part of spring. Their views are well supported by the known physical and chemical reaction of the majority of soils on potash salts and their usual saline admixtures."

40. Chloride of potassa contains 52.4 parts of potassium Pure sulphate of potassa contains 54.9 parts of potassium oxide and 46 parts of sulphuric acid.

41. Commercial muriate of potash contains an average of 50 per cent. of actual potash. As a means of reducing its value to the price per pound of actual potash, the Connecticut Experiment station publishes the following table:

If quoted at 2.00 cents per pound. Actual potash costs 3.93 cents per pound.

42. The nitrogen of commercial fertilizers is derived from numerous sources, varying in their cost and value; among these we may enumerate bone, tankage, fish scrap, nitrate of soda, sulphate of ammonia, dried blood, guano, cotton and linseed pomace and sundry matters, the refuse of other manufactures.

43. Experiment stations assign these various values, but in the following order, and in the following ratio: Ammonia salts, nitrates, ground fish, guanos, dried blood, meat, cotton seed pomace, and in fine bone, eighteen cents per pound; in fine medium bone, sixteen cents; in medium bone, fourteen cents; in course medium bone, fourteen cents; and in course bone, horn shavings and hair, ten cents per pound.

44. In sales from the wholesale dealer to the manufacturer and among manfacturers, nitrogen and nitrogenous materials are sold by the "unit" of nitrogen; that is by the per cent. of nitrogen which they are guaranteed to contain. Thus goods guaranteed to run ten per cent. would be styled "ten units," and others in like proportion. When thus sold the nitrogen is usually quoted as ammonia.

45. In order to facilitate the calculations of the cost per pound of nitrogen, the price per "unit" being given, the Connecticut Experiment station has published the following table:

Ammonia at $4 00 per unit is equivalent to nitrogen at 24.3 cents per pound.

46. When the nitrogen is purchased in the form of a sulphate of ammonia, which on a average contains 20.5 per cent. of nitrogen, the price per pound of the sulphate being given. The following table from the same source is convenient for ascertaining the cost per pound of nitrogen:

At 5 cents per pound. Nitrogen costs 24.4 cents per pound.

47. That the atmosphere is perhaps one of the greatest sources of the nitrogen of plant life, but that the popular opinion that plants can by absorption take it direct from the atmosphere, is in all probability erroneous, and that it must pass first into the soil and there undergo certain changes which fit it for plant food.

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48. The two terms nitrogen" and "ammonia" are interchangable, and are alike used in relation to commercial fertilizers; inasmuch as the ammonia is represented by the largest figures, manufacturers usually prefer to state it in this form. To change the ratio from one to the other we have but to remember that fourteen of nitrogen are equivalent to seventeen of ammonia; hence to change nitrogen into

its equivalent of ammonia we have to multiply by seventeen and divide by fourteen; to change ammonia into nitrogen the reverse is the rule.

49. Some writers divide ammonia, as present in the soil, and fertilizers into two parts, viz, actual and potential; by actual ammonia is meant such ammonia as is in a soluble form and immediately available as crop food; by potential ammonia is meant such ammonia as is not directly available, but which from chemical changes in the soil sooner or later becomes available.

50. Materials containing "organic nitrogen," or "potential ammonia" do not, to any great extent, pass directly into the hands of farmers; they are usually purchased by fertilizer manufacturers at prices. which place them beyond the reach of the consumer until they have been mixed with potash and phosphoric acid and take the form of a fertilizer.

51. Fertilizers have been, for the purpose of classification, divided into two divisions, viz: Complete and incomplete; a "complete fertilizer," is said to be one which contains nitrogen, phosphoric and potash; an "incomplete fertilizer" is one which contains but one, or at most two of these classes of elements; of the former class our ordinary superphosphates may be taken as samples; of the latter class we have dissolved South Carolina rock as a sample.

52. Strictly speaking, a "complete fertilizer" is one which supplies to any soil all of the ingredients of plant growth which it lacks, and a complete fertilizer" for one soil or one crop may be an incomplete one for another.

53. As a rule, all root and leguminous crops require a large proportion of potash, and hence we find all "special" fertilizers for these crops running unusually high in potash; on the other hand, grain crops generally need a preponderance of phosphoric acid; clover is also a large consumer of nitrogen, but seems able, in most cases, to derive the necessary supply from the atmosphere through the soil.

54. The nitrogen of fresh stable manure, by fermentation, is easily and rapidly changed into ammonia and nitric acid, and in this form is volatile and readily lost. If this fermentation can be prevented a great loss of valuable material may also be prevented.

55. Of nitrate of soda Prof. Aitkin writes as follows: "Nitrate of soda is the cheapest and almost the only ready formed nitrate used as manure. It is a true manure. The name "stimulant," frequently used, is a popular error, based upon a misapprehension of its character and use as a nourisher of plants. It is the most soluble and most active of nitrogenous manure at the command of the farmer and these characters determine the circumstances in which it should be used and the mode of its application.

56. Aitken also claims that the solubility of nitrate is such that it rapidly diffuses itself through a damp soil, and to render it available as plant food requires much less moisture than any other form of nitrogen. He also states that "plants are liable to take up nitrates by their roots only when phosphates are in a readily available form and potash salts are present in the soil."

57. It has been claimed that the continued application of nitrate, without a corresponding amount of phosphoric acid and potash, will, by producing a good crop, gradually but surely exhaust the supply of phosphoric acid and potash in the soil.

58. Inasmuch as the nitrate of soda is sold by the pound and of a

certain guaranteed strength, the following table from the Connecticut Experiment Station report is valuable for determining its cost per pound; the table assumes as a basis that the nitrate will average 95 per cent. of the pure salt, which will give 15.6 per cent. of nitrogen: If quoted at 3 cents per pound. Nitrogen costs 23.2 cents per pound.

59. Dr. A. P. Aitkin, chemist of the Highland Agricultural Society of Scotland, in summarizing the results of the society's experiments with nitrogen, draws the following conclusions as to the relative value and merits of sulphate of ammonia and nitrate of soda as a source of nitrogen.

60. When equal amounts of nitrogen were applied over a rotation in the form of nitrate of soda, and of sulphate of ammonia, it was found that the former was, on the whole, the more productive manure; but these two manures, although closely allied in some respects, have each its special use, and they should not be used indifferently.

61. "Sulphate of ammonia is a less active manure than nitrate of soda, presumably for the reason that it has to be converted into nitrate before it is available for the use of the plant. The relative utility of these two forms of manure may be best understood by keeping that idea clearly in view.

62. "When nitrogen is wanted for the immediate nourishment of the plant, the nitrate is to be preferred; when a less immediate and more prolonged action is wanted, the sulphate is to be preferred; when both an immediate and a prolonged action are wanted, a judicious mixture would seem desirable.

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63. For crops whose growth is rapid, and whose duration is short, the nitrate is, on the whole, preferable, therefore it is very useful for cereals sown in the spring; but when the crop has a long period of growth, as in the case of root crops, the sulphate of ammonia exercises a manurial influence long after the nitrate has disappeared.

64. "Sulphate of ammonia should, therefore, be applied with the seed of cereals rather than as a top-dressing. When sulphate of ammonia is applied as a top-dressing it causes an aftergrowth, which may seriously retard the time of ripening.

65. "Sulphate of ammonia is more firmly retained by the soil than nitrate of soda, so that, unlike nitrate of soda, it cannot be entirely washed out by rain. It is, therefore, more suitable for a wet district, or a wet season, than uitrate of soda. On the other hand, sulphate of ammonia is not so well suited for application to rapidly growing crops in dry districts or in a season of drought.

66. "During a dry season nitrate of soda, being immediately available if applied with the seed, may save the crop by forcing away the young plant at once, and enabling its roots to get hold of moisture in the lower soil and subsoil before the drought has become severe.

* See republication by the New York State Agricultural Society.