WINTER MEETING. 437 



growth, and thus controls indirectly the markets of the world. Upon the 

 presence of these three substances the value of all commercial fertilizers 

 depends. The least important of these three is potassium. Its value depends 

 largely upon the quality of the soil and of the crop to be produced. AVhile 

 in heavy soils there is generally a sufficient amount of potassium present for 

 the use of most crops, in light soils the quantity is nearly always deficient. 

 If you have a good, heavy clay soil and can add plaster and work it thoroughly, 

 or if you have plenty of good wood ashes to use, and if you are careful not to con- 

 tinue to crop with plants that use up a large amount of potassium, you might 

 thus far starve out the best fertilizer company in the world. In regard to 

 settling the question of growth with most crops, the business portions of the 

 triumvirate firm are phosphorus and nitrogen, but they form a diumvirate 

 that stands ready to make a corner on every spear of grass or grain, every 

 stalk of corn and even every pumpkin vine that the farmer attempts to raise. 



Phosphorus is one of the most important elements of plant food and one 

 which is generally present in the soil in a comparatively small amount, hence 

 in a good fertilizer there should always be present quite a large per cent of 

 phosphorus, yet the amount of phosphorus present does not determine its 

 value, but the proportion of this amount that is in such a form that the plant 

 can use it. Fine bone meal and guano supply this element in such a form, 

 but coarse bones and mineral phosphates must first be treated with acid, 

 which converts them to their soluble form and the fertilizer is then called a 

 sii'perplioi^'phate. When the fertilizer has stood for a time, or after it is 

 applied to the soil, some of the soluble phosphoric acid becomes insoluble in 

 water or changes to a form that is called reverted phosphoric acid. When 

 the treatment with sulphuric acid has not been thorough, there is some in- 

 soluble phosphoric acid left. We then have in every fertilizer three forms of 

 phosphoric acid. The soluble, the insoluble, and the reverted. The soluble 

 and reverted are of about equal value and are together called available phos- 

 phoric acid. 



Last but not least is the nitrogen, the most valuable element of plant food 

 and the one generally soonest exhausted in the soil. Although the air is 4-5 

 nitrogen, yet the total supply of this element to the plant must come either 

 from the ammonia or the nitric acid, or the organic nitrogen found in the 

 soil. The ammonia and the nitric acid are the active forms, while the activ- 

 ity of the organic nitrogen varies greatly, depending on the combination of 

 the elements present. The ammonia and organic nitrogen are the forms in 

 which the nitrogen is found in the commercial fertilizer. 



Thus far we have noted the chemical value of commercial fertilizers as 

 plai.t food. Let us now notice briefly the intrinsic or actual money value of 

 the fertilizer. It is a popular and wide-spread idea that a commercial ferti- 

 lizer is an extremely doubtful mixture of all those substances that could be 

 used for no other purposes in the world, and it is not doubted that there is 

 possibly present in the mixture a little guano, a dead horse or two, a small 

 quantity of very short cigar stubs, a few pounds of waste leather, greasy rags, 

 oyster shells and an exceedingly large amount of sand, and that the whole 

 process is a mine of wealth for the manufacturers. There may have been 

 foundation for such an idea in the fertilizers of the past, but a company that 

 should attempt to maimfacture a fertilizer of that description to-day would be 

 exceedingly short-lived. The legislatures of nearly every State, gaining wis- 

 dom from past experiences, have passed laws relative to the manufacture, 

 composition and sale of commercial fertilizers. 



