HOW TO COMPUTE AMOUNT OF FERTILIZER. 15 



How to Compute tbe Amount of Fertilizer in 

 a Given Formula. 



It is very important that we should be able to com - 

 pute the amount of any essential fertilizer element 

 contained in a certain formula. Unless we are able to 

 find this out, we cannot make an intelligent use of the 

 substance. Very often a high grade and a low grade 

 fertilizer can be obtained on the same market then 

 it is very essential that the relative values of these 

 shall be obtained in order that we buy intelligently. 

 It does not concern us further than the difference in 

 handling, whether we have to use a half ton or a ton 

 of fertilizer to get the requisite amount of an essential 

 element ; so, if we can get the requisite amount of a 

 certain element in low grade fertilizer for enough less 

 to pay for its handling and something over, that will 

 be the preferable kind to buy. To illustrate : Suppose 

 we have a fertilizer containing 10 per cent, available 

 phosphoric acid, 8 per cent, potash, and 6 per cent, 

 nitrogen. A ton of this gives 200 pounds (10 per cent, 

 of 2000 pounds a ton) phosphoric acid, 160 pounds 

 potash, and 120 nitrogen. The remainder is usually 

 some harmless earthy substance. Now, suppose there 

 is another fertilizer on the market that contains 6 per 

 cent, of available phosphoric acid, 6 per cent, of pot- 

 ash, and 4 per cent, of nitrogen. A ton will give us 

 120 pounds phosphoric acid, 120 pounds potash, and 

 80 pounds of nitrogen. The value of different fertil- 

 izing elements varies from year to year. We will use 

 figures that are approximately correct. If nitrogen is 

 worth 12 cents a pound, available phosphoric acid 10 

 cents, and potash 6 cents, we will have the following 

 comparison in values of the respective formulas ; 



