etc. In nitrogenous goods the price is usually stated at so much a unit of ammonia. This system, all things considered, is the most satisfactory to both purchaser and dealer, as the one gets exactly what he pays for, and the other is paid for all he delivers. The number of units in the material is determined by chemical analysis. At the present time this system is rarely used in the sale of mixed goods, but there is no reason why it should not be applied to these as well as to the unmixed materials.

Names of Fertilizers Sometimes Misleading.There is no doubt that in many cases an attractive name plays an important part in the sale of a fertilizer. Unfortunately the brand name of a fertilizer is not necessarily any indication of its composition. An instance in this connection is the abuse of the word, bone, by the fertilizer manufacturers. They are fully aware that the average farmer favors bone as a source of phosphoric acid, and as a consequence that word often appears in the brand name when it should not. There are licensed in a certain State over 100 fertilizers with the word, bone, occurring in the brand name, which either have none of the phosphoric acid derived from bone, or have at least a part of the phosphoric acid in the form of rock phosphate. Others are called humus fertilizers, when they contain practically no organic matter, which is the only source of humus. These facts emphasize the statement that the buyer should carefully study the bulletin from the control station, and base his purchase wholly on the cold facts therein stated. It may be said in passing that there is a movement on in several states to revise the ferti

lizer laws so as to compel the maker of fertilizers to state the materials entering into the composition of a brand, as well as its content of the three essential ingredients. Such a law if possible of enforcement would be a distinct advance over the present system.

Cooperative Buying.-Money can always be saved by buying large quantities, for the dealers are justified in giving better prices on large lots, and as a rule better freight rates can be secured. Where a number of farmers in a community are using the same kind of goods it will be to their advantage to buy cooperatively through the granges or farmers' clubs. The crude materials especially can be bought more cheaply in this way. In some places, a certain mixture has been found to be satisfactory by a number of farmers, and they have the goods mixed by a manufacturer in accordance with their own specifications calling for a certain formula and specific ingredients. This method usually gives better results than the indiscriminate purchase of the so-called standard brands. As a general rule it may be said that, taking the precaution to compare the commercial valuation and the selling price, it is always wise to purchase high-grade fertilizers.

Trade Values not Agricultural Values.-The values for commercial fertilizers and manures which have been discussed are trade values, and do not necessarily bear any relation to the agricultural value of these substances. Trade values are determined by the law of supply and demand, and many of the materials used in commercial fertilizers are required by other industries as well, so it is not the agricultural demand alone that sets the price. The agricultural value of a fertilizer is

measured by the value of the increased crop produced by its use, and is, therefore, a variable factor depending upon the availability of its constituents, and the character of the crop to be raised. It is possible to have circumstances under which a fertilizer with a comparatively low commercial valuation may have a high agricultural value.

Must Know what Fertilizer is Needed.—It is not sufficient to know how to calculate the commercial value of a fertilizer, and to be able to determine if the price asked is reasonable. One must also know the food requirements of the crop, and the condition of the soil before he can intelligently purchase fertilizers. A piece of land which was deficient in potash, for instance, would not be benefited by the use of a fertilizer which contains little or no potash, but which might be of great value when used elsewhere. In other words, the purchaser who desires to buy that which will give him the best returns must be guided by chemical analysis even more than by the commercial valuation.

Home Mixing the Most Rational Practice.-The idea of mixing the fertilizers on the farm is daily becoming more popular. This is attested by the fact that every year a larger number of dealers in fertilizers are offering for sale the unmixed goods. Already it has been noted that the plant food can be purchased at a lower cost in the basic materials, and that the form of combination is often as important as the actual amounts present. It is only by buying the unmixed goods that one can be certain of the form of the plant food. But aside from these considerations

there is an educational value in the use of the separate ingredients, which is lost when mixed goods are employed. This fact has been aptly stated in a bulletin from the New York station at Geneva, as follows: "There is little of educational value in using an unknown mixture. To purchase intelligently unmixed fertilizing materials will ultimately lead in most cases to a well grounded knowledge of the science of agriculture. One will seek to know what the different forms of plant food are, what they do, from what source they can be obtained, and how he can use them to best advantage. He will become to some extent an investigator and will of necessity take a deeper interest in his work. His entire system of farming will be lifted to a higher plane, and his more intelligent labor will yield more profitable results."

CHAPTER XXII

INDIRECT FERTILIZERS

Soil Amendments.-There are a number of substances which are beneficial to the land under some conditions, although they add neither humus nor important quantities of plant food. Such substances have been called soil amendments, and the benefit derived from their use arises from the fact that they produce certain changes in the soil, which directly, or indirectly, promote plant growth. Some of these amendments contain small amounts of plant food, but their value is chiefly due to their secondary effect, and not that they add nitrogen, phosphoric acid or potash.

Lime an Important Indirect Fertilizer.-Lime is probably the most important substance of this class, and its use as a manure antedates the Christian era. Although lime has been employed as a fertilizer for so long a time, it is only in recent years that its action has been explained, and at the present time there remain for investigation many questions concerning the action of lime upon the soil.

In a few instances lime has a direct manurial value, for occasionally a soil is found which is so lacking in this substance that the crops are unable to obtain sufficient lime for a maximum yield. Such soils are rare, and in nearly every instance the good results from the use of lime are due to its indirect effect. The effects of lime may be considered to be of three kinds, i. e., physical, chemical and biological.

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