856 
Journal of Agricultural Research 
Vol. XXVH, No. IX 
proportion, since 56 per cent of the total phosphorus was in the grain 
and cob and 29 per cent in the leaves. Approximately 45 per cent of the 
potassium occurred in the leaves, 32 per cent in the stem and only 19 
per cent in the grain and cobs. More than 58 per cent of the calcium 
was in the leaves, while the stems and roots contained 18 and 19 per 
cent, respectively. The proportion of calcium in the ear was small and 
amounted to slightly more than 4 per cent of the total calcium in the 
plant. In contrast to the calcium, more than 39 per cent of the 
magnesium occurred in the grain and cob while the proportion of this 
element in the leaves and stem amounted to 32 and 21 per cent, 
respectively. The leaves contained 39 per cent of the sulphur, the 
stem 22 pea: cent and the grain and cob 26 per cent. Approximately 
22 per cent of the iron was found in the leaves, while the stem and grain 
each contained 15 per cent of this element. The leaves contained the 
greater part of the silicon, since over 62 per cent of the total amount of 
this element occurred in them. The ear contained about 1.5 per cent 
of the silicon and of this amount less than one-half per cent occurred in 
the grain. The leaves and the stem contained most of the chlorin; 
42 per cent of this element occurred in the former and 36 per cent in the 
latter. Approximately 44 per cent of the manganese occurred in the 
grain and cob and over 27 per cent in the leaves. The roots contained 
6.3 per cent of the nitrogen, 4.2 per cent of the phosphorus* 3.7 per cent 
of the potassium, 19.5 per cent of the calcium, 6.7 per cent of the 
magnesium, 10.6 per cent of the sulphur, 44.1 per cent of the iron, 27.5 
per cent of the silicon, 66.4 per cent of the aluminum, 5.4 per cent of the 
chlorin and 14.8 per cent of the manganese. The relatively large pro¬ 
portions of calcium, iron, silicon and aluminum in the roots was due in 
part, probably, to the minute soil particles that were partially embedded 
in the surface of the roots and were not removed in the preparation of 
the material for analyses. 
WEIGHT OE THE ELEMENTS REMOVED FROM THE AIR AND SOIE BY AN 
ACRE CROP OF CORN 
Since so many factors can influence the yield and composition of plants, 
any data concerning the amount of the various elements removed per 
acre for a given crop are applicable only for the cultural and climatic 
conditions under which the plants were grown. The recent work of 
Duley and Miller (1) concerning the effect of the supply of nutrients upon 
the character and composition of the com plant especially emphasizes 
this fact. In the experiment herein reported, the plants were grown in 
42-inch rows and the plants in the row thinned to a distance of 2 feet. 
If the stand were perfect under these conditions, there would be 6,270 
plants per acre, but in order to allow some leeway 6,200 plants were con¬ 
sidered as the stand per acre in estimating the yield of dry matter. The 
total dry matter produced by 6,200 plants, the average dry weight of 
which, including the roots, was 834.9 gm., would amount to 11,389 
pounds per acre. Since the dry matter of the roots weighed 60.5 gm. 
per plant, the dry matter produced per acre by them would amount to 
825 pounds. The total dry weight of the plants above ground would 
thus amount to 10,564 pounds per acre. The average dry weight of 
the lower foot of the stem was determined in order to ascertain the 
amount of dry matter left on the field by the stubs when the plants were 
cut at a height of 1 foot from the ground. The average weight of the 
lower foot of the stem was 28.3 gm. If 6,200 plants were considered as 
