98 Development and Activities of Roots of Crop Plants. 



On June 28, when the plants had an average height of about 10 inches, 

 containers 5 and 6 were removed (fig. 40). A glance at table 32 shows that 

 the seals in the check container were preventing appreciable water-loss, while 

 any intake in the surface 6 inches had apparently been balanced by evapora- 

 tion. During the interval of 13 days since the last examination of container 

 5, 4 per cent of water had been lost from the surface 8 inches, but this was 

 less than half the absorption from the 8 to 16 inch level, while 15 per cent 

 had been absorbed from the 1.3 to 2 foot depth. Clearly, the roots at this 

 stage of development were more active in the deeper soil. Unfortunately 

 the 2 to 2.5 foot samples were lost in drying. The roots of the 20 plants in 

 this container extended to the 2.5 foot-level and were very abundant at a 

 depth of 2 feet. These data indicate that the surface roots were much less 

 actively absorbing than the deeper, younger portions. The loss in the top 

 8-inch layer may be accounted for in part by new roots from the tillers, as 

 well as from the parent plant. Considerable water was still available at all 

 depths, since the hygroscopic coefficient is rather uniformly about 10 per 

 cent (c/. table 10). 



On July 16, containers 9, 10, and 11 were excavated, opened, and examined. 

 The plants were about 2.3 feet tall, had tillered extensively, and were in the 

 early milk stage. The roots were uniformly distributed throughout the soil, 

 except that they were less abundant at depths of 2.8 to 3.5 feet, i. e., below 

 the working level (fig. 40). An examination of table 33 (sixth column) shows 



Table 33. — Water-content of soil at several intervals to July 16. 



1 Eleven plants, mostly with 3 to 7 tillers; 2.3 feet tall and in the milk stage. 



2 Twelve plants, mostly with 3 to 5 tillers each, some with 7; about 2.3 feet tall and in milk 

 stage. Roots uniformly distributed, except not so abundant in last 6 to 9 inches. 



* No plants. 



