264 



PLANT PHYSIOLOGY 



The law of the minimum estabUshed by Liebig has played ai 

 important role in the development of fertilizer practice and i& 

 one of the great discoveries of this scientist. But numerous 

 investigations of many scientists later on established with 

 certainty that the different fertilizers do not act independently 

 of each other, as was stated by Liebig and his followers, but 

 that complicated interrelations may be observed in their activity. 

 The plant is not indifferent to the relative proportions in which 

 it obtains the necessary elements. It is known, for instance, 

 that an increase in the amount of nitrogen augments the require- 

 ments of the plant for phospliorus and potassium and that the 

 requirements of plants for mineral elements are greatly influenced 

 by climatic conditions, in particular by moisture conditions, etc. 



61. Consumption of Mineral Elements by Different Plants. 

 The Accumulation of Mineral Elements by Plants at Different 

 Stages of Growth. Relation of Plants to the Content of Calcium 

 Salts in the Soil. — The chemical composition of the ash of plants 

 is variable, depending largely on the environmental conditions 

 under which the plants are grown, their general properties, and 

 their age. It has already been noted that the dryer the climate 

 and the greater the amount of salts in the soil, the higher will be 



The Composition of Ash of Some AcxRIcultural Plants 



Plants 



Seeds: 



Wheat 



Corn 



Clover 



Flax ... 



Beans 



Stems and 



leaves : 



Wheat 



Corn 



Clover 



Flax 



Buckwheat. 

 Tubers and 



roots : 

 Potatoes. . . 

 Sugar beets . 

 Turnips. . . . 



CI 



0.9 

 1.2 



1.8 



3.4 



4.8 

 5.0 



