e phosphate, the mixture ought to be
made just previous to application.

_Manurial Ingredients should be applied separately._

The question of applying manure in mixtures is one on which considerable
difference of opinion may exist. For many reasons manures are often
better applied in the unmixed condition. For example, a mixture of a
quickly acting nitrogenous manure with a slowly acting phosphatic manure
is not suitable. In such a case either the nitrogenous manure will be
applied too long before it is required by the plant, and thus suffer
from risk of loss, or the phosphatic manure will not be applied long
enough before it is likely to be used. By applying manures in an unmixed
condition the chances are that a more economical use of them is made
than would otherwise be the case. On the other hand, while the
application of the separate constituents may be desirable from the
scientific point of view, it involves a considerable amount of extra
trouble. Of course a further consideration is the desirability in many
cases of having a complete manure. The above hints, therefore, on the
risks of loss which exist in mixing manures, may be of service to the
agricultural student.

FOOTNOTES:

[247] See p. 389.

CHAPTER XXV.

ON THE VALUATION AND ANALYSIS OF MANURES.

_Value of Chemical Analysis._

The value of a manure to the farmer depends on the proportion of
_nitrogen_, _phosphoric acid_, and _potash_ it contains, as well as--and
this is hardly less important--the condition in which the ingredients
are present. Since these facts can alone be determined by a chemical
analysis, it is obvious that manures should always be purchased with a
chemical analysis. It is unfortunate, however, that very often a
chemical analysis, even when procured, is unintelligible. It may be of
advantage, therefore, to say a word or two on the correct interpretation
of the significance of the data furnished in the ordinary chemical
analysis of manures.

_Interpretation of Chemical Analysis._

The first thing that the farmer ought to look for in the analysis of a
manure is the amount of nitrogen, phosphoric acid, and potash which the
manure contains.

_Nitrogen._

The percentage of nitrogen in a manure is generally stated as equal to
its equivalent percentage of ammonia. Very often, indeed, in the older
analyses, its equivalent of ammonia was alone stated. Now this statement
does not necessarily imply that the nitroge