88 
AMERICAN AGRICULTURIST. 
[March, 
Science Applied to Farming.—XV. 
By Prof. W. O. Atwater, Director of Connecticut 
Agricultural Experiment Station, Wesleyan 
University, Middletown, Conn. 
Interesting and Important: Experiments on 
Plant Growth —Essential Ingredients of 
Plant Pood—Potash and Starch—Practical 
Conclusions—Fertilizers. 
The accompanying Illustration is engraved from a 
photograph of one of a series of experiments per¬ 
formed by Dr. Nobbe and his assistants at the Agri¬ 
cultural Experiment Station at Tharandt in Saxony. 
They belong to a large number of similar re¬ 
searches, which have been carried on in order to dis¬ 
cover what materials are required as food by plants, 
and how the plants use them-Until quite recent¬ 
ly no one knew what constitutes the real food of 
plants, how much of the material of the plant came 
from the air and how much from the soil, what was 
needed for fertilizing crops, nor how the required 
materials could be best obtained in manures. But 
years of patient work by many investigators in the 
chemical analysis of plants, soils, and manures, and 
in the culture of plants in the greenhouse, and of 
crops in the field, have thrown a vast flood of light 
upon these dark problems. This work has been 
EXPERIMENT IN WATER-CULTURE. 
BY DR. NOBBE, AND ASSISTANTS, AT TIIE AGRICULTURAL EXPERIMENT STATION IN THARANDT, SAXONY. 
The above engraving we copy from photographs of Buckwheat Plants, grown with the roots immersed in jars containing various solutions of 
the ingredients of plant-food in water. The plants were supported by perforated corks resting on the covers of the jars, and by upright sticks. In 
jars I and 7a was a normal solution, that is, a solution containing all the essential ingredients of plant-food, including potassium as chloride. 
The plant in la. was nearly 31 feet high. The solution in II was the same as normal solution in I and la, except that potassium uas 
omitted in the jar II. The plant teas scarcely 3 inches high. The jar II 3 commenced as II, that is without potassium, but potassium chloride 
icas afterwards added. VI contained the normal solution, except that sodium was substituted for potassium. IX, X, XI, and III, same 
as I, except that IX contained no lime , X no chlorine, and XI no nitrogen, and III had nitrate instead of chloride of ptotassium. 
done, in large part, in tbe Agricultural Experiment 
Stations, and has given us definite knowledge of 
incalculable value_In order to a full understand¬ 
ing of some of the more important results of these 
investigations, let me recall to those who are not 
well versed in the science, a few 
Important Facts in Chemistry. 
Phosphoric acid combined with lime, as phosphate 
of lime, makes up most of the mineral matter of all 
bones.— Sulphuric acid, (oil of vitriol), with lime, 
forms sulphate of lime, otherwise known as “plas¬ 
ter,” or gypsum.— Silica is the chief ingredient of 
ordinary sand. It occurs nearly pure in flint and 
quartz, and, combined 
with other substances, 
in many minerals.— Ni¬ 
trogen constitutes four- 
fifths of the air, the 
other fifth being oxy¬ 
gen ; and nitrogen also 
makes up about seven- 
eighths of ammonia, the 
rest being hydrogen.— 
Charcoal and lampblack 
are nearly pure carbon. 
—By potash is to be 
understood the com¬ 
pound of potassium and 
oxygen, and by soda, 
sodium and oxygen.— 
Beaming these facts in 
mind, let me quote the 
following tersely ex¬ 
pressed statement by 
Prof. S. W. Johnson, 
of some of the substan¬ 
tial results referred to : 
“In respect to tbe 
food of plants, it has 
been settled that potash, 
lime, magnesia, iron, 
phosphoric acid, and sul¬ 
phuric acid must be 
furnished to all agricul¬ 
tural plants through 
their roots and by the 
soil, iu order to their 
growth. It has also 
been shown that soda, 
silica, and chlorine arc 
not needful forthe early 
growth of grain crops, 
but that chlorine is es¬ 
sential for the perfec¬ 
tion of the seed, and 
that silica is probably 
necessary to uniform 
blossoming and ripen¬ 
ing. It is further proved 
that water must enter 
crops through their 
roots; that carbon, 
which constitutes more 
than half their weight, 
is superabundantly fur¬ 
nished by the air; that 
air and water together 
yield the materials out 
of which fully 90 to 98 
per cent of crops is 
built up ; and that the 
soil has to give for their 
nourishment only the 2 
to 8 per cent of mineral 
matters which remain as 
ashes when they are 
burned, and the one 
and a half to two per 
cent of nitrogen which 
they also contain.” 
Essential I»S redi- 
ents of Plant-food. 
In order, then, that 
any agricultural plant 
may grow, it must have 
at its disposal, in the 
soil, besides water, a 
