THE RARER ELEMENTS IN SOILS AND PLANTS. 15 
ment station, where the soil contains less than 1 per cent lime, the amount 
in the sisal ash was but 7 per cent. 
White* found considerable variation of the lime content of clover 
grown in soils of different reaction. The figures are as follows: 
Alkaline, 3.02 per cent Ca; neutral, 2.68 per cent Ca; and acid; 2.67 
per cent Ca. 
The attention of the bureau has frequently been called to instances 
of clovers and alfalfas growing on acid soils. In one such case at 
Carrollton, Mo., samples of alfalfa were submitted that had been 
growing luxuriantly on an apparently acid soil for eight years. The 
growth exceeded that of some alfalfa fields where the soil reaction 
was apparently more favorable. Mr. J. G. Smith, of this bureau, 
found the lime requirement of this soil to be 3 tons of CaO to the 
acre. He also found that the total lime and magnesium in the soil 
was much higher than the average. An examination of the tables — 
shows that this alfalfa, No. 3, contains somewhat less lime, but more 
magnesium than the eastern alfalfas. It appears that in this case 
the alfalfa had extracted the amount of lime and magnesia neces- 
sary for normal growth from the calcium and magnesium silicates 
in the soil and therefore that compounds of these elements are neces- 
sary for the elaboration of plant tissue, rather than to give an alka- 
line reaction to the soil. 
There are wide variations in the composition of the same kind of 
plants, and from the data here presented it can not be stated whether 
these are due to difference in the stage of growth or to a difference 
in the composition of the soil. All things considered, however, it 
would seem that the most profound influence the composition of the 
soil has on the plant is not on the composition of the plant but on 
the occurrence of that plant on the soil. To be concrete, it seems 
that a plant will not grow naturally, seeding itself year after year, 
on a soil where it can extract only a part of the normal amount 
of any element necessary for its growth. Diligent search failed to 
show any legumes, which are high in lime, growing on York silt 
loam in Bethany, S. C. This soil contains only 0.08 per cent total 
CaO. . 
It may be a mere coincidence, but in the majority of cases where 
_ the plant contains a comparatively large amount of rare alkalies, 
there is also an abnormal amount of manganese present. The chlorine 
of plants that have been cultivated is high, particularly those that 
are usually fertilized with commercial fertilizer. Such large amounts 
of chlorine may not be necessary for the elaboration of plant tissue, 
but it seems that chlorine and sulphuric acid act as necessary vehi- 
cles to carry the alkalies from the soil to the plant. In the cotton 
1 Ann. Rept. Pa. State College Agr. Expt. Sta., 1913-14, p. 46. 
