tting in and
harvesting a crop of chicken-feed and weeds. Artificial manures give us
a grand chance to make our crops more uniform."

"You are certainly right there," said the Doctor, "but let us examine
the Rothamsted experiments on barley."

You will find the results in the following tables. The manures used,
are in many respects the same as were adopted in the wheat experiments
already given. The mineral or ash constituents were supplied as follows:

_Potash_--as sulphate of potash.
_Soda_--as sulphate of soda.
_Magnesia_--as sulphate of magnesia.
_Lime_--as sulphate, phosphate, and superphosphate.
_Phosphoric acid_--as bone-ash, mixed with sufficient sulphuric
acid to convert most of the insoluble earthy phosphate of
lime into sulphate and soluble superphosphate of lime.
_Sulphuric acid_--in the phosphatic mixture just mentioned; in
sulphates of potash, soda, and magnesia; in sulphate of ammonia,
etc.
_Chlorine_--in muriate of ammonia.
_Silica_--as artificial silicate of soda.

Other constituents were supplied as under:

_Nitrogen_--as sulphate and muriate of ammonia; as nitrate of
soda; in farm-yard manure; in rape-cake.
_Non-nitrogenous organic matter, yielding by decomposition, carbonic
acid, and other products_--in yard manure, in rape-cake.

The artificial manure or mixture for each plot was ground up, or
otherwise mixed, with a sufficient quantity of soil and turf-ashes to
make it up to a convenient measure for equal distribution over the land.
The mixtures so prepared were, with proper precautions, sown broadcast
by hand; as it has been found that the application of an exact amount of
manure, to a limited area of land, can be best accomplished in that way.

The same manures were used on the same plot each year. Any exceptions to
this rule are mentioned in foot-notes.

Experiments on the Growth of Barley, Year After Year, on the Same
Land, Without Manure, and With Different Descriptions of Manure, Hoos
Field, Rothamsted, England.

Table I.--Showing, _taken together with the foot-notes,_ the
description and quantities of the manures applied per acre on each
plot, in each year of the twenty, 1852-1871 inclusive.

[N.B. This table has reference to all the succeeding Tables].

---------+------------------------------------------------------
|Manures per Acre, per Annum (unless otherwise
Plots | stated in the f