102 Development and Activities of Roots of Crop Plants. 



barley that two weeks after germination the plants in containers with sodium 

 nitrate in the first foot of soil were readily designated by a number of unin- 

 terested observers. The difference in growth on December 11 in the unfer- 

 tihzed soil of container 12 and that of container 1, where the first foot was 

 enriched with nitrates, is shown in plate 10. At this time a few of the plants 

 had begun to tiller and by December 20 many of the new shoots had three 

 leaves. The plants stood up well, although considerably attenuated because 

 of the low light intensity, while throughout the experiment the more abundant 

 foliage, broader leaves, and darker green color marked the containers with 

 nitrates added in the first and second feet. 



On December 21 container No. 5 was taken down and the root system 

 examined. The plants averaged 8.5 inches in height (maximum 14 inches), 

 but the roots were abundant in the first foot of soil only, a few having pene- 

 trated a distance of only 4 to 6 inches into the second foot. Thus, during this 

 period of 47 days, the above-ground parts had developed scarcely further 

 than plants grown in the field for only 27 days, while the root extent was not 

 much more than half as great (table 31). 



From January 18 to February 22 the crops were watered from time to time 

 through the opening in the oilcloth cover and wax seal. Water was added 

 slowly, so that it penetrated the sand between the wooden strips bordering the 

 wax seal and entered the soil below. In this manner a total of 4 Hters was 

 added to each of the larger containers and 3.1 hters to each of the smaller ones. 



Late in February, the crop, although very short, began to head, but growth 

 proceeded so slowly that by March 12 only a few heads had appeared and none 

 had blossomed. The development of the crop at this time is summarized in 

 table 36, while plate 11 illustrates the difference in growth in the fertilized 

 and unfertiHzed soils. 



Table 36 shows that in general the plants in containers with nitrates 

 added to the first or second foot (viz, Nos. 1, 2, 3, 4, 9, and 10) were taller, had 

 a greater number of leaves per plant, and that the leaves were wider and of a 

 dark-green color. Thus the nitrates stimulated vegetative growth, but did 

 not promote flower production. However, even the best developed plants 



