n | 0.297 | 0.149 |
| Equal to ammonia | 0.360 | 0.180 |
| Containing nitrogen | 0.309 | 0.613 |
| Equal to ammonia | 0.375 | 0.744 |
| Total nitrogen | 0.606 | 0.762 |
| Equal to ammonia | 0.735 | 0.924 |
+-------------------------------+-------------+-------------+

On examining and comparing these analyses, it appears that the
differences are by no means great, although, on the whole, they tend to
show that, weight for weight, well-rotten dung is superior to fresh,
provided it has been properly treated. Not only is the quantity of
valuable matters existing in the soluble state materially increased,
whereby the dung is enabled to act with greater rapidity, but, owing to
evaporation and the escape of carbonic acid, produced by the
decomposition of the organic substances, the proportion of those
constituents which are most important to the plant is increased. This is
particularly to be noticed, in regard to the nitrogen, which has
distinctly increased in all cases in which the dung has been kept for
some time; and the practical importance of this observation is very
great, because it has been commonly supposed that, during the process of
fermentation, ammonia is liable to escape into the air. It would appear,
however, that there is but little risk of loss in this way, so long as
the dung-heap is left undisturbed; and it is only when it is turned that
any appreciable quantity of ammonia volatilizes. It is different,
however, with the action of rain, which soon removes, by solution, a
considerable quantity of the nitrogen contained in farm-yard manure; and
the deterioration must necessarily be most conspicuous in rotten dung,
which sometimes contains nearly half of its nitrogen in a soluble
condition. The effect produced in this way is conspicuously seen, by the
results of weighings and analyses of small experimental dung-heaps, made
by Dr. Voelcker at different periods. The subjoined table shows the
composition of the heap, lying against a wall, and exposed to the
weather at different periods:--

+--------------------------+-------------------------------------------+
| | WHEN PUT UP. |
| +---------+------------+---------+----------+
| | Nov 3d | April 30th | Aug 23d | Nov