26 BOARD OF AGRICULTURE. [Jan. 



ficial ; but the cases are rare. These little bottles that I 

 have here show you the exact amount of each of these con- 

 stituents that was in the single stalk of corn, and of the six, 

 four may, in most cases, be disregarded ; the other two, 

 namely, phosphoric acid and potash, are needed and must 

 be provided for in old soils. 



The phosphoric acid, that is always spoken of in fertilizer 

 analyses, is this white powder which I have in this bottle ; 

 so that an analysis showing twelve per cent of phosphoric 

 acid, means that in one hundred pounds of the fertilizer 

 there are twelve pounds of this white substance. 



Now, what have we shown thus far? 



1. That a crop of twenty tons of ensilage corn is made 

 up of various substances, some of which come from the soil, 

 others from the air. We have seen that 39,490 pounds oiit 

 of the total forty thousand comes from the air, either as water 

 or carbonic acid. Also, that 263 pounds of the ash is nearly 

 always over-abundant in the soil ; leaving 177 pounds of ash 

 to be provided, either wholly or in part, and seventy pounds 

 of nitrogen, a part of which, at least, must be supplied. 



Potash is very essential, for not a grain of starch can be 

 formed in its absence ; and as starch or some similar sub- 

 stance is the foundation of all the other parts of a plant, 

 it follows that a plant cannot grow without potash. Phos- 

 phoric acid has some direct influence in the production or 

 transfer of the albuminoids, and is especially valuable in 

 those crops that contain a large amount of the latter. 



How has it been sliown that Nitrogen, Phosphoric Acid and 

 Potash are needed hy Crops? 



The whole science of fertilizers dates back to the acci- 

 dental discovery that bone produced favorable results when 

 used in place of animal manures. This discovery was made 

 by a farmer in England, as long ago as 1750. It is true that 

 lime, plaster and nitrate of soda were used previous to this, 

 but no attempt was made to ask why they gave increased 

 yields. 



In 1750, or about that time, an English farmer made use 

 of the waste bone and burnt chips and shavings which the 



