Depths at Which Plants Absorb Water and Nutrients. 109 



On May 25, when the barley had reached an average height of 1.6 feet 

 (maximum height 1.7 feet) and was unfolding the sixth or seventh leaf, con- 

 tainers Nos. 1 and 2 were examined (plate 12b). The soil in these containers 

 was fertilized at the 1 to 1.5 and 1.5 to 2 feet depths respectively, wax seals 

 being inserted both above and below these levels. The position of these 

 layers, together with the root development, is shown diagramatically in figure 

 42. It may be noticed that the roots in container 1 are not so abundant below 

 the 1.5-foot level as in container 2. The presence of the fertihzed layer in the 

 first container evidently caused this phenomenon, which, in fact, was observed 

 in several other cases. Wherever the roots of any of the crops entered fer- 

 tihzed soil, the degree of branching was very much more pronounced. Table 

 39 gives a summary of the water and nitrate losses during this 55-day period. 



A study of table 39 shows that the roots absorbed almost as much water 

 from the second 6-inch layer of soil as from the first, and also that the water- 

 content below the seal in the 1 to 1.5 foot layer was considerably reduced. 

 The nitrate-content of the soil, as in the following tables, includes not only 

 the NO3 of the NaNOs added, but all NO3 present in the soil when analyzed 

 at the beginning and end of the experiment, respectively. The nitrate- 

 losses at depths of 1 to 1.5 and 1.5 to 2 feet respectively show clearly the root 

 activities at these levels. 



On June 13 the barley in containers 6, 7, and 8, and the potatoes in con- 

 tainers 3, 4, and 5 were examined. The barley had developed quite evenly 

 with that grown outside of the containers and was in the blossoming stage, 

 although a few of the older heads had begun to fill. The plants had tillered 

 well. The crop had an average height of about 2.8 feet, except that those 

 plants in container 7, which had been sHghtly damaged by frost, were only 

 about 2.5 feet tall (maximum 3.2 feet, plate 13 a). The potatoes were 1.7 

 to 2 feet tall, had developed normally as compared with those in an adjoining 

 field, and were just beginning to blossom. The position of the wax seals 

 inclosing the fertilized soil layers and the extent of the root development is 

 shown in figure 42. Here again the effect of the fertihzed soil upon limiting 

 root penetration, as well as increasing the degree of branching, is patent. 

 That the wax seal offered no obstacle to root penetration is clearly shown in 

 plate 9 c, where a portion of the seal taken at a depth of 2 feet from container 

 8 is shown. The high degree of root development in this fertihzed layer (depth 

 2 to 2.5 feet) is also shown in the same plate. Glass funnels 3 inches in 

 diameter and partly filled with coarse sand were placed inverted in the several 

 containers at depths indicated in table 40. These were connected with large 

 glass tubes which extended 2 inches above the soil-surface, where they were 

 kept corked. These furnished a means of adding water to the soil. The 

 loss of water and nitrates, together with the crop development, is given in 

 table 40. 



A survey of table 40 shows that the amount of water absorbed by the 

 potatoes, while not so great as in the case of barley, was quite uniform in 

 the several containers and corresponds well with root depth and distribution. 

 The nitrates removed at the different levels, while quite marked in amount, 

 were also less than that used by barley. Water-losses from the containers 

 with barley were greatest from the first foot (7 to 13 per cent), but large 

 quantities had also been removed from the second-foot layers (2 to 7 per cent), 



