ortions of the field not covered by
the manure-heaps are thus manured with washed-out farmyard manure,
bereft of its most valuable constituents. The result is, that while
certain portions of the field are too strongly manured, other portions
are too weakly manured.

3. The proper fermentation of the manure is apt to be interfered with by
the loss of that which is its most important agent--viz., the soluble
nitrogenous matter--and also by the drying action of the wind.

The same objections hold good to a large extent with regard to the
setting out in the fields of the manure in large heaps. The risks of
loss, in one respect, may be said to be less, owing to the smaller
surface presented. On the other hand, they may be greater, owing to
fermentation taking place more quickly. Agricultural practice, however,
often renders this custom necessary; and if precautions are taken not to
let the heap lie too long, and to cover it over with earth, the risk of
serious loss may be rendered inconsiderable.

With regard to the second method of procedure--viz., the spreading of
the manure broadcast over the field, and allowing it thus to lie--Dr
Heiden is of opinion that this should only be done when the field is
level. In the case of uneven ground the risks are, of course, obvious.
It has been affirmed that, by allowing farmyard manure thus to lie
exposed for some time, an important loss of volatile ammonia--carbonate
of ammonia--is apt to take place. This could only take place where the
former treatment of the farmyard manure had been bad. Hellriegel has
shown that in the case of properly prepared farmyard manure there is no
danger of loss in this way. The absorptive power of the soil for
ammonia, it must be remembered, is very great, and the amount of
volatile ammonia in farmyard manure is relatively so small that it is
scarcely possible that any could escape in this way. Hellriegel's
experiments have demonstrated this in a very striking way. He has found
that in the case of a chalky soil, and during the summer and autumn
months, practically no loss of ammonia takes place. The following
considerations may be further urged in support of this method of
application, as against immediately ploughing in the manure, viz.:--

1. That fermentation takes place more quickly.

2. That it results in a more equable distribution of the manurial
constituents in the dung, by gradually and thoroughly incorporating the
liquid portion of the manur