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· Fertilizer Laws and Guarantees.—It is impossible for the farmer to determine the kind and proportion of the different materials entering into the composition of a fertilizer by its appearance, weight, smell or any physical examination. Formerly all commercial fertilizers were sold without any guarantee of their composition. The injustice done to the purchaser under such a system, has resulted in the passage of laws, in most States, which require the manufacturer, or dealer, to give the actual amounts of the different constituents contained in these products. The manufacturers are compelled to guarantee the percentage of nitrogen (or ammonia), available phosphoric acid, and potash that each brand contains, and usually the composition must be stated on each bag or parcel of the fertilizer that is offered for sale. The enforcement of this law, and the chemical examination of the fertilizers to determine if they agree with the guarantee, are entrusted to the Experiment Stations in some States, while in others they are in the hands of the State Department of Agriculture. The results of the analyses of the various brands are published in bulletins for free distribution, and these should be generally consulted by the farmers using fertilizers. One result of the fertilizer laws has been greatly to reduce the number of brands offered for sale, and the decrease has fallen in a great measure on the low grade goods, as the worthlessness of a large number of such brands has been exposed by chemical analysis.

Guarantees are Often Confusing.-The only constituents that should be taken into consideration in the purchase of a mixed fertilizer are nitrogen (or ammonia), available phosphoric acid, and potash. These must be stated in the guarantee, and the fertilizer laws are so well enforced in most States that the buyer is safe in assuming that he will receive the guaranteed amount of these three constituents. The laws, however, do not prevent the use of other statements on the bags. The result is that in many cases superfluous words and reiterations are used, apparently with the intent of confusing the purchaser. Phosphoric acid 10 per cent, for instance, is often stated as equivalent to bone-phosphate 22 per cent, whether the phosphoric acid actually comes from bone or from rock phosphate. The unwary consumer sees the larger figure, 22 per cent, and is led to believe that he is obtaining something more than the 10 per cent of phosphoric acid which is all that is guaranteed. Potash, likewise, is often stated as equivalent to sulphate of potash, whether or not the sulphate is used in its manufacture. The following example taken from the label on a brand of fertilizer on the market illustrates this point.

The only point of interest to the buyer in this statement of analysis is the per cent of nitrogen (or ammonia), available phosphoric acid, and potash. In the state in which this fertilizer was found on sale, am


Per cent.
Nitrogen . . . . . . . . . . . .82 to I
Equivalent to ammonia . . . . . . . I to 2
Available phosphoric acid . . . . . . 8 to 10
Equivalent to available bone phosphate . . 18 to 22
Total phosphoric acid . . . . . . . 9 to 12
Equivalent to bone phosphate . . . . . 25 to 30
Potash actual . . . . . . . . . 2 to 3
Equivalent to sulphate of potash . . . . 3.5 to 5

monia is guaranteed instead of nitrogen. As the dealer is held liable only for the lowest amounts stated in the guarantee, this statement, when shorn of its redundant expressions would read as follows:

Per cent. Ammonia . . . . . . . . . . . . I Available phosphoric acid ........ 8 Potash . . . . . . . . . . . . . . 2

Consult the Control Bulletin.—In buying fertilizers as in the purchase of other commodities it is desirable to get the highest possible return for the money invested. It has been pointed out that more plant food can be obtained for the money in the unmixed basic materials than in any kind of mixed fertilizers, but in spite of this fact there are undoubtedly large numbers of persons who will continue to buy mixed goods for years to come. The attention of such persons is again called to data given on page 215, showing the relative cost of plant food in high and low grade fertilizers. Whatever form is used the fertilizer should be purchased only on the basis of its analysis as shown by the bulletin from the control laboratory, or in case this is impossible, on the basis of the lowest amounts of nitrogen (or ammonia), phosphoric acid and potash which it is guaranteed to contain. In many States the bulletins referred to give in addition to the analysis the calculated trade value or commercial valuation. This in most instances represents what would be the actual cost of the amount of the three valuable ingredients of the fertilizer, if they were purchased for their average retail trade price. Where such a table is available the farmer will do well to consult it before making his purchase, and in general terms it may be said that he should never pay for a mixed fertilizer very much in excess of the price a ton given in the commercial valuation.

Calculating the Commercial Value of a Fertilizer. -The purchaser, in the majority of instances, should be governed in the price he pays for a fertilizer by the valuation placed on it by the control station. In some states this valuation is not given, or the prospective buyer may not be in possession of the bulletin. In this case the commercial value of the fertilizer may be calculated easily from the guaranteed analysis. First de. termine the number of pounds of nitrogen, available phosphoric acid, and potash, in a ton of the fertilizer. Then multiply by the value a pound (15 cents for nitrogen and 5 cents each for phosphoric acid and potash), and the sum of the results so obtained will be the retail value of the crude material used in the fertilizer. A simple method which will give very nearly the commercial valuation of a fertilizer is to multiply the percentage of ammonia by two and one-half, add the product to the percentages of available phosphoric acid

and potash, and the result will be the commercial value of a ton of the fertilizer in dollars and cents.

Example:-The fertilizer mentioned above is guaranteed to contain i per cent of ammonia, 8 per cent of available phosphoric acid and 2 per cent of potash. Multiplying 1 by 2.5 gives 2.5. To this add 8 and 2 and the result is 12.50, which means that the commercial value of the fertilizer is $12.50 a ton. In case the analysis states nitrogen instead of ammonia the nitrogen should be multiplied by 3, and added to the avaliable phosphoric acid and potash. The valuation determined in this way should be compared with the selling price of the fertilizer, and the difference should never exceed $5 a ton. It is of interest to note that the fertilizer mentioned in the example retailed for $21 a ton. This is an excess of $8.50 over the cost of the crude materials, which is just the average cost of mixing, etc., as determined by Voorhees (see page 216). In calculating the value of the fertilizer the buyer must shut his eyes to everything but the lowest guaranteed per cent of the three essential ingredients, and must not allow himself to be confused by any statements of equivalents.

Unit Basis of Purchase.—In commercial transactions most of the quotations of the crude materials used in the manufacture of fertilizers are based on the unit. A unit means i per cent on the basis of a ton, or 20 pounds. For example a unit of available phosphoric acid would be 20 pounds, and if the quotation was $1 a unit the phosphoric acid would cost 5 cents a pound. This system is applied to the sale of nitrate of soda, the potash salts, blood meal, tankage, superphosphate,

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