SOILS AND FERTILIZERS 399 



not be the poorest, the chances are that those which contain all forms 

 are likely to give more satisfactory results. 



It [potash] is, however, a very necessary constituent of fer- 

 tilizers, being absolutely essential for those intended for light, sandy 

 soils and for peaty meadow lands, as well as for certain potash-con- 

 suming crops, as potatoes, tobacco and roots, since these soils are 

 very deficient in this element, and the plants mentioned require it 

 in larger proportions than do others. 



Potash exists in various forms, but it differs from the other ele- 

 ments in that its chemical form or combination seems to exert but 

 relatively little influence upon the availability of the constituent. 

 For example, it may be in a form of muriate or chlorid, of a sulphate 

 or of a carbonate, and while there is a difference in the diffusibihty of 

 these different compounds that is, a difference in the rate at which 

 they will distribute in the soil before becoming fixed there seems 

 to be very little difference in the rate of the absorption of the potash 

 by the plant. Nevertheless, the form of potash must be observed, 

 because of the possible influence that the substances with which it 

 combines may exert in reducing the marketable quality of the crop 

 to which it is applied. This influence has been very distinctly ob- 

 served, particularly in the growing of tobacco, sugar beets, and po- 

 tatoes, and it has been shown that the potash in the form of a chlorid 

 (or muriate) does exert a very deleterious effect, especially on 

 tobacco. 



In the purchase of mixtures, consumers should demand that 

 they be accompanied by a guarantee, because they are unable to 

 determine the kind and proportion of the different materials enter- 

 ing into the mixture, either by its appearance, weight or smell. In 

 mixing, too, an opportunity is afforded for disguising poor forms of 

 the constituents, particularly nitrogen. That is, in a mixture of 

 nitrogenous materials, potash salts, and superphosphates, it would 

 be a difficult matter to determine, by mere physical inspection, the 

 proportion of the nitrogen which had been supplied in the form of 

 norn meal and of blood, and the statement of the manufacturer on 

 this point would be valuable in proportion to his reliability. 



An analysis may show simply the total amount of the constitu- 

 ents. This is not a sufficient guide as to the value of the mixture, 

 for while it is not possible to indicate absolutely by analysis whether 

 the organic nitrogen, for example, is derived from blood (which is 

 one of the best forms) or from horn meal (one of the poorer forms) 

 it is possible to show whether the nitrogen is derived from nitrate 

 or from ammonia, whether the phosphoric acid is derived from a 

 superphosphate or a phosphate, and whether the potash present is 

 in the form of a sulphate or of a muriate. A high-grade or a low- 

 grade fertilizer, for example, may be distinctly indicated by the 

 analysis, since it is of a high grade if the three forms of nitrogen 

 are present, if the total phosphoric acid is chiefly soluble in water, 

 and if the potash has been derived from a sulphate or from a mu- 

 riate. It is obvious, that the value of a fertilizer to the farmer de- 



