20 



the turms used and know tlie commercial value of the diiferent plant food 

 constituents. 



Statement of Guakantee. 



The statement of a guarantee should be as simple as possible. All that 

 is required is the per cent, of nitrogen, potash and available phosphoric acid. 

 The amount of insoluble phosphoric acid miay also be given, but as little value is 

 placed on this part of the material it is not important. Sometimes, however, the 

 per cent, of nitrogen is given and its equivalent of ammonia. This is simply two 

 ways of stating the same fact. Again, phosphoric acid may be quoted in terms of 

 'Vater soluble," "citrate soluble," "available," "insoluble," and "total." Out of 

 all of these statements the only one that is required is the "available," or, if we 

 want to know the amount of other forms of phosphoric acid, the "insoluble" may 

 be included. The potash is also very often stated in two ways, as "potash" and 

 as "equal to sulphate of potash." This again is a statement of the amount in 

 two ways. In rare instances the fuller statement may be of interest to a purchaser. 

 Unfortunately, the Act does not limit the number of times and ways the manu- 

 facturer may state the same thing in the guarantee, and consequently he is within 

 his rights in multiplying the number. The purchaser, however, will do well 

 to remember that no matter kow complex the guarantee may be the valuation 

 should be made on the three itemis: (1) "nitrogen," (2) "available phosphoric 

 acid," and (3) "potash." This fact is recognized in the concise statement used in 

 speaking of a fertili^^er as being a 3-6-10. The meaning is that it contains 3 per 

 cent, of nitrogen, fi per cent, of phosphoric acid, and 10 per cent, of potash. 



Teade Names. 



The need of a guarantee is emphasized by the great number of different brands 

 of fertilizers on the market. The trade name given a particular brand is usually 

 an indication of the crop to which it should be applied, as " Potato Manure," 

 "Grape and Small Fruit Special," " Orchard Special," " Tobacco Grower," etc. 

 Doubtless these preparations are well adapted to the requirements of the plants, 

 but it is impossible to make any one mixture that will give the best results with 

 all kinds and conditions of soils. The trade named substances are useful and are 

 an attempt to furnish a fertilizer that is properly balanced for the particular crop 

 named. This, however, does not mean that any fertilizer named for a particular 

 crop will under all conditions give the best results. 



To use fertilizers intelligently it is absolutely necessary that a study be made 

 of the fertilizers themselves and the crop and soil requirements. The first can only 

 be got by studying the literature on the subject and by observation. The second 

 can be best got by reading and experimenting. 



CALCULATION OF THE VALUE OF FERTILIZERS. 



The true money value of fertilizers cannot be estimated. This would be 

 measured by the increased crop produced and it is manifestly impossible to fix 

 a value to any fertilizer which would be correct under the varying conditions of 

 climate, soil, crop, season, and method of use. It is important, however, for 



