VALUATION OF FERTILIZERS 121 



sources, or from any two or perhaps be furnished from all of 

 these sources. The potash may be as sulphate, or as chloride, 

 or as carbonate, or as a mixture of any two or three of these 

 forms in any proportion. 



Here is still another statement. 



Chemical An.\lysis, No. 4. 



Per cent. 



Nitrogen 4.00 



Available phosphoric acid 10.00 



Potash 9.00 



This analysis besides not furnishing the amounts of the forms 

 of nitrogen and potash does not give the forms of phosphoric 

 acid. Of this 10 per cent, available phosphoric acid all of it 

 may be as soluble, or as reverted. It may contain both soluble 

 and reverted phosphoric acid but in just what amounts we do 

 not know. 



The chemical analysis, when the different forms of plant food 

 are reported, may often prove of value to those farmers who can 

 interpret them and who understand the influence of the plant food 

 forms on profitable crop production. 



Agricultural Values. — The agricultural value of a fertilizer 

 is represented by the crop produced. The price that is paid for 

 a fertilizer has no bearing on its agricultural value. The agri- 

 cultural value will vary with the season, the amount of fertilizer 

 used, the nature of the soil, kind of crop, care of the crop, locality, 

 insect damage, plant diseases, and many other conditions. It 

 cannot be estimated and is often beyond the control of man. 

 However, the nature of the materials that make up a fertilizer 

 may influence its agricultural value. Market garden crops will 

 no doubt do better with fertilizers containing plant food in 

 available and soluble forms. For example, available phosphoric 

 acid will give quicker returns than insoluble phosphoric acid. 

 Nitrogen in a soluble form will be taken up more readily than 

 nitrogen in an organic form and some organic forms of nitrogen 

 will be more quickly available than others. In other words 

 fertilizers that give up their i)lant food slowly will not have a 

 high agricultural value for ([uick growing crops. 



