FERTILIZERS 



169 



difference in the purity of the salts will show in the results 

 of certain experiments. The soil grown check plants had a 

 dry weight equivalent to the full nutrient plants in these 

 experiments. It is of interest to note that the plants grew 

 appreciably better with tap water than with distilled. This 

 shows the unusual dilution, as found in tap water, from which 

 salts can be absorbed. 



A TABULATION OF THE CHIEF FUNCTIONS AND GENERAL SYMPTOMS 



OF DEFICIENCIES OF THE ELEMENTS TAKEN 



FROM THE SOIL 



Element 



Functions in the Plant 



Symptoms of a Deficiency 



Nitrogen 



Phosphorus 



Potassium 



Calcium 



Magnesium 



Iron 



Sulphur 



Manganese 



Boron 



Zinc 



Copper 



Constituent of protein, protoplasm, 

 and chlorophyll molecules. Excess 

 produces large plants. 



Constituent of nuclear protein. Im- 

 proves root growth and seed for- 

 mation. Aids in enzyme actions. 



Essential for photosynthesis and 

 sugar translocation. Improves 

 quality of fruit. 



Aids in absorption of other elements 

 and in root growth. 



Constituent of chlorophyll. Neces- 

 sary for formation and use of oils. 



Essential for synthesis of chloro- 

 phyll. 



Constituent of protein. Aids nodule 

 formation in clovers. 



Used in oxidation process and 

 chlorophyll synthesis. 



Necessary for cell division. 



Not clear. 

 Not clear. 



Small plant, 

 of leaves. 



Yellow-green color 



Poor root growth. Bluish-green 

 leaf color. Shorter internodes. 



Stunted growth. Premature death. 

 Small chlorotic leaf spots. 



Poor root growth. Buds and 



young stems stunted. 

 Chlorotic rusty spotting of older 



leaves. 

 Lack of chlorophyll and poor root 



growth. 

 Poor root system and vigor. Re- 

 sembles plants low in nitrogen. 

 Chlorotic leaves and death of the 



youngest ones. 

 Young buds and leaves become 



brittle and break off easily. 

 May cause "little leaf" and "white 



bud" diseases. 

 At least some plants fail to grow 



seed. 



Fertilizers are usually purchased with a guaranteed per- 

 centage analysis of available nitrogen, phosphorus, and po- 

 tassium. These three elements together are called a com- 

 plete fertilizer, and are expressed as a 4-12^ fertilizer, when 



