TIIIC I-ERriLITV Ol- THE SOIL 



17 



One Element Cannot Replace Another. — It must be understood 

 that no one of these essential elements can take the place of 

 another, as each has its particular functions to perform which 

 are different for each element. Therefore should a soil be de- 

 ficient in any of these essential elements, the addition of those 

 that are lacking will tend to produce good crops, provided other 

 conditions are favorable. Let us illustrate this by supposing we 



I-'ig- 2.— I, Unfertilized; 2. Potash, phos. acid, nitrogen; 3, phos. acid, nitrogen. 

 Courtesy German Kali Works. 



wish to plant a field of corn. We have perhaps plenty of avail- 

 able phosphoric acid, potash and lime for the needs of the corn 

 and the land is in good condition, but the available supply of 

 nitrogen is deficient in the soil. We cannot grow a profitable 

 crop of corn under such conditions because the phosphoric acid, 

 potash and the lime are unable to take the place of the nitrogen, 

 no matter how abundant they may be. Should nitrogen be sup- 

 plied in sufficient amount the crop would be satisfied and should 

 prove profitable, other conditions being right. 



