EXPERIMENT STATION BULLETINS. 519 



EXPLANATION OF TABLES. 



The results of analysis showTi in the following tables are arranged by man- 

 ufacturers, in alphabetical order. Those found below guarantee are printed 

 in bold face type. 



Nitrogen—It will be noted that the results under this heading are divided 

 into four columns. The column headed "As Soluble" shows the amount 

 of nitrogen that is soluble in water. This would include all nitrogen present 

 as nitrate of soda, sulfate of ammonia, cj'animid, etc. This i^ortion of the 

 nitrogen is considered to be immediately available. 



The second and third columns together represent the nitrogen that is 

 insoluble in water. This insoluble nitrogen is separated into ' 'active' ' and 

 ' 'inactive' ' nitrogen depending upon its reaction with an alkaline solution of 

 potassium permanganate. When the amount shown "as active insolul^le 

 organic" is greater than that shown "as inactive insoluble organic" the 

 whole insoluble nitrogen is considered to be of good quality. In other w^ords, 

 it has been derived from some high grade material possessing a high rate 

 of availability or the material used has been treated in such manner as to 

 render it largely available. If, on the other hand, the amount of nitrogen 

 shown in the ' 'inactive' ' column is greater than that showTi in the ' 'active' ' 

 column then the insoluble nitrogen is considered to be low grade wth a low 

 rate of availability. When the insoluble nitrogen constitutes a small per- 

 centage of the total, its rate of availability would, of course, be of small 

 consequence. But, where the ' 'insoluble nitrogen' ' constitutes a considerable 

 portion of the total, as is very often the case, then its rate of availability 

 is an important factor. 



Since nitrogen is, by far, the most expensive plant food ingrecUent in fer- 

 tilizers, more attention should be given to the results printed in the follow- 

 ing pages under this heading and when purchasing nitrogenous fertilizers 

 preference should be given those companies that show the insoluble nitrogen 

 nitrogen in their mixtures to be derived from high grade materials. 



The fourth column shows, the total amount of nitrogen in the sample. 

 It is equal to the sum of the first three columns. 



Phosphoric Acid — Three divisions are included under this heading, desig- 

 nated as "total", "insoluble" and "available." The "total" phosphoric 

 acid includBs all of this ingredient in the sample. The ' 'insoluble' ' phosphoric 

 acid respresents that portion that is unavailable and the "available" phos- 

 phoric acid, is, as the name implies, readily available. The available phos- 

 phoric acid represents the difference between the total and insoluble phos- 

 phoric acid. 



Potash — The results shown under this heading are those soluble in water 

 as required by the law. Water soluble potash is, of course, readily available. 



