it should be clearly understood. In the words of the late
Dr Voelcker: "Direct experiments have shown that 100 cwt. of fresh
farmyard manure are reduced to 80 cwt. if allowed to lie till the straw
is half rotten; 100 cwt. of fresh farmyard manure are reduced to 60 cwt.
if allowed to ferment till it becomes 'fat or cheesy'; 100 cwt. of fresh
farmyard manure are reduced to 40-50 cwt. if completely decomposed. This
loss not only affects the water and other less valuable constituents of
farmyard manure, but also its most fertilising ingredients. Chemical
analysis has shown that 100 cwt. of common farmyard manure contain about
40 lb. of nitrogen, and that during fermentation in the first period 5
lb. of nitrogen are dissipated in the form of volatile ammonia; in the
second, 10 lb.; in the third, 20 lb. Completely decomposed common manure
has thus lost about one-half of its most valuable constituent."[167]
While, of course, a very great amount of absolute loss of the valuable
constituents--the nitrogen and ash-constituents--of farmyard manure may
take place through volatilisation and drainage, by taking requisite
precautions this loss may be very much minimised. As regards the total
loss, this, in two or three months' time, should only amount to 16 to 20
per cent--or one-sixth to one-fifth of the weight.[168] The use of
fixers, to which reference has already been made, will greatly minimise
this loss. The application of fixers is best made to the manure when
still in the stall or byre. The health of the animal benefits by so
doing, while the manure is at once guarded against loss from this
source.

As to the relative merits of covered and uncovered manure-heaps, much
difference of opinion exists. It is one of those questions which does
not admit of final decision one way or another, as it depends so largely
on the individual circumstances of each case. That manure produced under
cover is more valuable than manure made in the open is readily granted.
The question, however, is as to whether the increase in its value is
sufficiently great to warrant the extra expense involved in building
covered courts. This depends on the individual circumstances of each
case, and cannot be decided in a general way. For experiments on the
relative value of manure made under cover and in the open, see
Appendix.[169]

The method of applying farmyard manure to the field is a question which
belongs more to the practical farmer than, to the scient