348 The Application of the Manure of the Farm. 
separate condition, farther comment is necessary. We have 
been gradually brought to the conclusion, that although liquid- 
manure does possess valuable fertilising powers, yet these gener- 
ally exist in such a diffused state that the cost of application 
exceeds its value, and hence it is a very generally accepted rule 
that the distribution must be accomplished by its own power of 
gravitation, or under some cheap pressure. When liquid-manure 
can be distributed over the land in an inexpensive manner, it 
becomes important to consider the influence exerted by its 
dilution. In the general practice of irrigation we observe the 
fertilising influence of the ingredients, thus added to the land, 
very much increased in consequence of their being presented to 
the roots of the herbage in a very diluted form — a condition in 
which it is especially favourable for the requirements of the 
plant. Nor are we without evidence that the action of any 
given quantity of liquid-manure may in like manner be in- 
creased by a similar dilution ; but in the practical application 
of this experience we have first to consider the cost of distribu- 
tion, and then increase the dilution in proportion to the porosity 
of the land. 
This addition of water simply effects a mechanical change 
in the liquid-manure, but there are chemical changes which 
alter its composition, and which must not be overlooked. A 
somewhat similar fermentation takes place in liquid-manure 
to what we observe in farmyard-dung, whereby we have am- 
moniacal salts formed in it. It has been doubted whether 
this change should be allowed to take place before or after 
its application to the land. If the liquid-manure is to be 
applied to a light soil, it will be desirable for this change to 
take place before it is used, because we cannot have it too well 
prepared for at once promoting vegetable growth. It may not 
be as necessary when applied to soils containing an admixture 
of clay ; for, although we are not at present in a position to say 
that the same production of ammonia will take place in the soil, 
still we have reason to believe that no direct loss will ensue. 
Hitherto the evidence of experience has been strongly in favour 
of keeping the liquid-manure in the tank until it has fermented, 
l)ut this experience, it must be added, has been chiefly derived 
from trials on light soils. It is possible that future trials may 
show, that upon stronger and more adhesive soils, the manure 
may be used fresh with greater advantage ; but at present the fer- 
mentation before distribution is generally accepted as the best plan. 
We have next to notice the crops upon which its employment 
has been successful. Here we have conclusive evidence that 
upon our natural and artificial grasses its use has been most 
beneficial. The Italian rye-grass has produced under its stimu- 
