Depths at Which Plants Absorb Water and Nutrients. 115 



blossom (19 days later) it had removed 286 and 135 parts per million of the 

 nitrates from similar levels, and 168 parts per million from the 2 to 2.5 foot 

 level. At maturity it had removed 186 parts per milUon from the 2.5 to 3 

 foot level. Potatoes used the nitrates in smaller amounts. When beginning 

 to blossom (74 days old) they had removed 143 and 70 parts per million of 

 nitrates from the 1 to 1.5 and 1.5 to 2 foot layers respectively, and when 

 beginning to ripen (100 days old) 228 parts per million had been removed 

 at a depth of 1.5 to 2 feet, and 76 to 165 parts per million at the 2 to 2.5 foot 

 level. Agropyrum and Andropogon used nitrates from the second and third 

 foot in large amounts (124 to 378 part per million), while corn removed 203, 

 140, and 118 parts per milhon at depths of 3, 4, and 5 feet respectively. 



Under greenhouse conditions both tops and roots of barley developed so 

 poorly that Httle value is attached to such experiments when apphed to field 

 conditions. However, the absorption of water and nitrates to 2.5 feet (the 

 maximum depth of root extent) correlated nicely with root position and 

 development. 



In every case where roots came in contact with a fertilized layer they not 

 only developed much more abundantly and branched more profusely, but such 

 a layer apparently retarded normal penetration into the soil below. Thus it 

 seems that the depth at which the fertilizer is placed in field practice would 

 considerably affect root position and development. Fertilizing the surface 

 layers of soil in regions where these have very httle or no available water 

 during periods of drought would appear to be distinctly detrimental to normal 

 crop production. Finally, since the roots of crop plants are found to penetrate 

 just as deep, or even deeper, under field conditions as in the containers used 

 in these experiments, and since their development in every respect has been 

 found to be identical, we must conclude that the deeper soils are not only suited 

 to plant-Hfe, but that they play an exceedingly important part in the hfe of 

 the plant and deserve careful consideration in a study of crop production. 



