THE SOILS OF FLORIDA. 
41 
CHEMICAL ELEMENTS ESSENTIAL TO PLANT GROWTH. 
Of the eighty known elements only about ten are believed to be 
essential to the growth of plants. These are: Carbon, calcium, 
hydrogen, iron, magnesium, nitrogen, oxygen, phosphorus, potassi¬ 
um, and sulphur. Five other elements although probably not essen¬ 
tial, are commonly present in plants. These are: Aluminum, chlo¬ 
rine, manganese, silicon, and sodium. Aluminum and silicon make 
up a part of all clay minerals, and hence are indirectly essential to 
plants, constituting a part of the soils in which plants find anchor¬ 
age and grow. Flourine is sometimes recognizable in the ash from 
plants, and iodine seems to be normal to sea weeds and sometimes 
occurs in traces in land plants. 
RELATIVE ABUNDANCE OF THE ESSENTIAL PLANT ELEMENTS. 
The following table gives the amount of each of the ten essential 
elements in the earth’s crust, the ocean, and the atmosphere. The 
five non-essential elements commonly present in plants are also 
included. 
Table showing the amount of the essential plant elements in the earth’s 
crust, the ocean, the atmosphere, and in the kernel of corn. 
1 
NAME. 
1 
1 
In the 
Earth’s 
Crust 
(percent) 
1 ■ 1 
1 
In the 1 
Ocean 
(percent) 1 
1 1 
1 1 in the 1 
r Ai? e Kernel NOTES. 
(percent) I (percent)' 
I I A l 
1 
Calcium . 
3.44 
4.43 
2.40 
trace 
.11 
2.46 
.11 
.05 
.022 
.008 
.125 
1.760 
.300 
.340 
.004 
Derived by plants from 
the soil. (Nitrogen is 
derived chiefly al¬ 
though not entirely 
from the soil). 
Iron . 
Magnesium .... 
Nitrogen . 
.14 
75.50 
Phosphorus .... 
Potassium . 
Sulphur .. 
.04 
.09 
Hydrogen . 
.22 
.20 
47.07 
10.67 
6.400 
45.000 
46.000 
Derived by plants from 
sources other than the 
soil. From the water 
and the air. 
Carbon . 
.01 
23.00 
Oxygen . 
85.79 
Aluminum . 
Chlorine . 
7.90 
.07 
.07 
28.06 
2.43 
Commonly present in 
plant structure although 
regarded as non-essen¬ 
tial. 
2.07 
.013 
Manganese .... 
Silicon 
.014 
.013 
Sodium 
1.14 
The table is adapted from Professor C. G. Hopk'ns’ text on 
“Soil Fertility and Permanent Agriculture,” page 13. The estimate 
of the amount of each element present in the ocean and in the earth’s 
crust is that made by Professor F. W. Clarke as given in the preced¬ 
ing table. The estimated composition of the air is that of Sir Wil- 
