IO4 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



roots in place. When the plaster hardens the dirt is washed away 



by a stream of water. 



Sanborn 1 drove an iron frame into the soil, removed the soil in 



layers of one inch to the depth of a foot, and washed out the 



roots. The roots were dried and weighed in order to ascertain 



their distribution in the soil layers. 



At the Arkansas Experiment Station, 2 plants were grown in 



boxes 10 by 12 inches and 4 feet deep, and the quantity of roots 



in different layers of the soil was determined. These conditions 



are somewhat artificial, and the roots would probably penetrate 



deeper than in a natural soil. 



The results of the preceding experiments are summarized in 



the following table : 



Barley 96 per cent, of roots in first 7 inches (Utah) 



Corn 90 " " 7 



Corn 93 " " " 7 



Clover 4 years old -. 94 " "7 



Clover Evenly distributed between the first 2 feet 



(Arkansas). 



Millet 80 per cent, in the first 12 inches (Arkansas) 



Oats 96 " " 7 " (Utah) 



Orchard grass 90 " 20 (Arkansas) 



Peas Mostly in 12 to 18 inches of soil 



Potatoes 70 per cent, in 7th to i3th inch (Utah) 



Timothy 87 " in first 7 inches (Utah) 



Timothy 95 ' " 6 " (Arkansas) 



Wheat 92 " " 7 " (Utah) 



It appears that barley, corn, oats, timothy, and wheat developed 

 over 86 per cent, of their roots in the first seven inches of soil. 

 Most of the plant food and water which they take up must 

 necessarily be drawn from this layer. Clover, millet, peas, 

 orchard grass, and potatoes appear to send their roots deeper, but 

 these results (with the exception of the potatoes) are from the 

 Arkansas Station, where the plants were grown in boxes and not 

 in the free soil. Plants grown in boxes, as in the Arkansas 

 Experiment, would have a tendency to send their roots deeper 

 than plants grown in the natural soil, on account of the pulveriza- 



1 Utah Experiment Station, Bulletin 32. 



2 Bulletin 29. 



