122 CONSERVATION AND IMPROVEMENT OF SOIL 



confuse the ordinary buyer. For example, the following is a 

 common statement of analysis : 



Analysis 



Per cent 



Nitrogen 0.85 to 1.10 



Equal to ammonia 1.03 to 2.00 



Soluble phosphoric acid . . . 6.50 to 7.50 



Reverted 2.00 to 3.00 



Available 8.50 to 10.50 



Insoluble 1.50 to 3.00 



Total 9.00 to 13.00 



Potash (actual) 1.00 to 1.50 



Equal to sulfate of potash 2.00 to 3.00 



The minimum or first column only is guaranteed by the seller 

 under the law. As there are only three ingredients in the table 

 which are to be used by plants, the other six lines are superfluous. 

 The buyer should be interested only in the following three facts: 



Nitrogen 0.85 



Available phosphoric acid 8.50 



Potash 1.00 



This shows the need of eliminating from the analysis all but 

 the essentials. The insoluble portions of the phosphoric acid 

 should not be considered. Two thousand pounds or one ton of 

 this fertilizer would contain only seventeen pounds of nitrogen, 

 one hundred and seventy pounds of phosphoric acid and twenty 

 pounds of potash. This would be called a very low grade of 

 fertilizer, and contains much material which should not be handled 

 in an effort to fertilize the soil. Freight has to be paid upon it 

 and much hauling is required for material which is valueless. 

 When ready-mixed fertilizers are purchased those containing much 

 valuable plant food should be used. After eliminating the non- 

 essentials in the analysis the actual valuation may be determined 

 by multiplying the number of pounds of nitrogen in the ton by 

 twenty (cents); the number of pounds of phosphoric acid by six 

 (cents) and the number of pounds of potash by six (cents). 

 Adding these three values will give the real value of a ton of 

 the fertilizer. In the above example the nitrogen is worth 

 $3.40; the phosphoric acid $10.20 and the potash $1.20, giving a 

 total value for the ton of $14.80. As prices fluctuate the pound 

 values for these ingredients may be changed, but fertilizers of 

 different grades should always be compared on an equal basis. 



Fertilizer formulas are often indicated on tags and fertilizer 

 bags. They express the ingredients in the sample, expressed in 



