Depths at Which Plants Absorb Water and Nutrients. 107 



for water-content determinations and large composite samples for nitrate 

 determinations were secured at all levels at the time the containers were filled 

 and before the nutrient was added. 



BARLEY 



BARLEY 



POTATOES 



BARLEY 



BARLEY 



BARLEY 



CONTROL 



POTATOES 



POTATOES 



BARLEY 



9 10 



BARLEY WHEAT GRASS BIG BLUESTEM 



16 



FlQ. 42. — Diagram of containers and root development of crops, 1921. Horizontal lines (6 

 inches apart, except in last two) indicate position of wax seals and double vertical 

 lines position of nutrients. 



When the containers were filled within 2 inches of the tops, two thin wooden 

 strips, about 1.5 inches in width and as long as the diameters of the containers, 

 were placed edgewise and partially sunk into the soil so as to prevent the wax 

 seal from covering the area of soil (about 1.5 inches in width) in which the crops 

 were to be planted. Finally, the wax seal was covered with 2 inches of sand. 

 Next a light-green wooden roof, with sufficient slope to cause the water to 

 run off but with an opening 1.5 inches wide and as long as the diameter of the 



