1889.] 



PUBLIC DOCUMENT — No. 4. 



31 



Later, the same liquor was prepared with sulphuric acid, 

 giving sulphate of ammonia, which, to-day, is one of the 

 sources of nitrogen used in good fertilizers. The best 

 quality of this salt contains twenty per cent of nitrogen ; 

 dried blood contains fifteen per cent ; fish scraps, seven and 

 one-half per cent ; guano, fifteen per cent. 



How SHALL WE USE THESE MATERIALS? 



The most natural answer is : Buy some one of the multi- 

 tude of prepared fertilizers {^commercial fertilizers) . I do 

 not advocate this, however, for several reasons. 



1. The fertilizers found on our market are constructed 

 upon a wrong foundation, and are consequently, in my 

 opinion, poorly adapted to the wants of our crops. Let me 

 make this point clear. Take any ten fertilizers found on 

 our market and average their percentage of plant food, and 

 you will find about the following : — 



Phosphoric acid (total), . . . .12 per cent. 



Potash, 3 per cent. 



Nitrogen, 2 per cent. 



This is approximately the average composition. Now the 

 practical question is this : Does this ratio, or this combina- 

 tion, meet the requirements of our crops ? I answer, No ! I 

 have here a chart which shows you the nitrogen, phosphoric 

 acid and potash taken from the soil by the following crops, 

 per acre : — 



Now, you will see that these five crops took from the soil 

 173.4 pounds of phosphoric acid and 457.4 pounds of potash ; 



