da 1.30
Chloride of sodium 0.54
Sulphuric acid 1.49
Carbonic acid and loss 15.11
------
100.00

Nitrogen, phosphoric acid, and potash, are the most valuable ingredients
in manure. It will be seen that a ton of fresh barn-yard manure, of
probably good average quality, contains:

Nitrogen 12-3/4 lbs.
Phosphoric acid 6-1/2 "
Potash 13-1/2 "

I do not say that these are the only ingredients of any value in a ton
of manure. Nearly all the other ingredients are indispensable to the
growth of plants, and if we should use manures containing nothing but
nitrogen, phosphoric acid, and potash, the time would come when the
crops would fail, from lack of a sufficient quantity of, perhaps,
magnesia, or lime, sulphuric acid, or soluble silica, or iron. But it is
not necessary to make provision for such a contingency. It would be a
very exceptional case. Farmers who depend mainly on barn-yard manure, or
on plowing under green crops for keeping up the fertility of the land,
may safely calculate that the value of the manure is in proportion to
the amount of nitrogen, phosphoric acid, and potash, it contains.

We draw out a ton of fresh manure and spread it on the land, therefore,
in order to furnish the growing crops with 12-3/4 lbs. of nitrogen,
6-1/2 lbs. of phosphoric acid, and 13-1/2 lbs. of potash. Less than
33 lbs. in all!

We cannot dispense with farm-yard manure. We can seldom buy nitrogen,
phosphoric acid, and potash, as cheaply as we can get them in home-made
manures. But we should clearly understand the fact that we draw out
2,000 lbs. of matter in order to get 33 lbs. of these fertilizing
ingredients. We should _try to make richer manure_. A ton of manure
containing 60 lbs. of nitrogen, phosphoric acid, and potash, costs no
more to draw out and spread, than a ton containing only 30 lbs., and it
would be worth nearly or quite double the money.

How to make richer manure we will not discuss at this time. It is a
question of food. But it is worth while to enquire if we can not take
such manure as we have, and reduce its weight and bulk without losing
any of its nitrogen, phosphoric acid, and potash.

CHAPTER XIV.

FERMENTING MANURE.

Dr. Voelcker placed 2,838 lbs. of f