phate was added gave higher yields. It would seem, on the whole, that the use of floats with manure is worthy of a trial by anyone needing a phosphate fertilizer. Ohio Bulletin 134, recommends that the ground rock be used "as an absorbent in the stable, thus securing an intimate mixture with the manure in its fresh condition."

CHAPTER XIX

MIXED FERTILIZERS

Complete Fertilizers.-Mention was made of the fact that the basic materials described in the foregoing sections contain only one, or at most two, of the essential elements of fertility. By far the larger part of the commercial fertilizers used by the farmers in this country are purchased in the form known as complete fertilizers. A complete fertilizer, in the sense in which the word is used in trade, is one that contains nitrogen, phosphoric acid and potash, in proportions that are supposed to be suited to the requirements of farm practice. Practically all of these fertilizers are made by mixing two or more of the basic materials heretofore described, the different ingredients being so combined as to give the desired percentage of nitrogen, phosphoric acid and potash. In case the basic materials alone yield a product that is richer in the essential ingredients than is desired by the manufacturer, sufficient gypsum, dry earth, peat or other inert matter is added to bring the percentage of these ingredients down to the desired point. Materials added in this way are known as fillers.* * These fertilizers are indiscrim

*There is a mistaken notion which is quite prevalent that anything contained in a fertilizer except nitrogen, phosphoric acid and potash is a filler. As a matter of fact it is impossible to make any rational combination of the basic materials which will contain more than one-third of its total weight of the three "essential ingredients," for even in the

inately recommended for general use and all sorts of startling claims are made for them by the various manufacturers. They are offered as universal fertilizers, irrespective of the well known fact that soils differ widely in their characteristics and that the crops vary in their food requirements. To be sure, a fertilizer of this kind if sufficiently rich in nitrogen, phosphoric acid and potash might be made to produce a large yield on any kind of soil if used in quantities, but such a use of a fertilizer would result in adding some of the elements at least in amounts far in excess of the need of the crop. The profits of ordinary farming are not sufficient to warrant the application of any of the elements of plant food in larger quantities than is required by the plant. An economical use demands that fertilizers be adapted to the soil, and to the crop to be raised, and this end can rarely be attained by the use of complete fertilizers. A little thought on the part of the farmer will convince him that the use of these general fertilizers is irrational, and that to obtain the best results he must adopt some system of fertilization especially adapted to his particular conditions.

Special Fertilizers.-A large number of so-called special fertilizers now offered by the manufacturers are supposed to be adapted to the particular needs of a special crop or class of crops. Each fertilizer usually bears the name of the particular crop for which it is designed. Such fertilizers are offered for all of the

highest grade materials the nitrogen, phosphoric acid and potash are combined with other substances. A filler, properly speaking, is a substance added for the express purpose of diluting the fertilizer and usually contains no plant food whatever. No filler is used in the highest grade mixed goods.

prominent crops. There are found on the market, corn specials, tobacco specials, potato specials, trucker's favorite, etc., etc., many manufacturers offering a number of such products.

If such fertilizers were compounded with any regard to the requirements of the particular crop for which they were advocated their use would be a distinct advance over the use of the general complete fertilizers. Unfortunately their chief claim is in their attractive names, and their composition is rarely in accord with what scientific investigation has shown to be necessary for the crop. That these mixtures are not based on any scientific knowledge of the needs of the plant is shown by the fact that the specials offered for the same crop by the different manufacturers vary as widely in composition as do the fertilizers offered for different classes of crops. Yet these several makers are all claiming to have the best fertilizer for that particular crop. A recent bulletin giving the guaranteed analysis of the fertilizers offered for sale in the State of Ohio contains some data on this subject, and as the conditions in other states are undoubtedly similar, it may be interesting to call attention to a few facts. brought out by an examination of this bulletin. Fortyfour of the fertilizers on the list are especially recommended for potatoes under such names as, Potato Grower, Potato Special, Potato and Tobacco Special, etc. These specials are widely variable in composition as is shown by the following table which gives the guaranteed analysis of seven of them, selected to show the variation in per cent of ammonia, phosphoric acid and potash.

In view of such a lack of uniformity in composition, the farmer who places his dependence on these special fertilizers, must be at a loss to know which one to select. The general experience of farmers in the Eastern states where fertilizers have long been used on potatoes, indicates that the best combination for this crop is one that contains potash in excess of the phosphoric acid. Voorhees recommends a mixture containing nitrogen 3 to 4 per cent, phosphoric acid 6 to 8 per cent., and potash 8 to 10 per cent. In spite of this fact only four out of the forty-four specials mentioned above contain potash in amounts exceeding the phosphoric acid. And lastly, two-thirds of the special potato fertilizers contained potash in the form of muriate. The authorities are practically all agreed that the muriate is injurious to the potato, and that all the potash used on this crop should come from the sulphate, and yet only one-third of these fertilizers under discussion contained potash in this form. Similar discrepancies are found in the special fertilizers offered for crops other than the potato. These facts are sufficient to convince one that little dependence can. be placed upon the name under which a fertilizer is