The Pl<mt. 81 



The activity of this organ in this connection is shown by the 

 following figures quoted from King. The table expresses the 

 pounds of water required to produce 1 pound of dry substance in 

 the plant. 



Pounds of Water Required to Produce One Pound of Dry Substance. 



Kind of Plant Pounds of Water 



Dent Corn 309 .8 



Barley . 392.9 



Oats 522.4 



Red Clover 452.8 



Field Peas 477.4 



Potatoes 422.7 



When we consider that field crops require an amount of water 

 from three hundred to five hundred times as great as their own 

 dry weight, and that all of their nitrogen (except in the case of 

 leguminous plants) and all of their ash constituents are derived 

 from the soil with this supply of water, the great importance of 



Showing the power of the rutabaga to obtain its phosphorus from insol- 

 uble phosphates. 



Box. 1. Soluble phosphoric acid. 

 Box 2. Insoluble phosphoric acid Florida rock. 

 Box 3. Insoluble phosphates of iron and aluminum. 

 Box 4. No phosphate added. 



