1 Fes., 1902.] QUEENSLAND AGRICULTURAL JOURNAL. 79 
13rH Lesson. 
SECOND STAGE. 
Sometimes on farms, where a large number of horses and dairy cows and 
pigs is kept, a quantity of farmyard manure accumulates, and perhaps the 
farmer has so much other work on hand that he has not time to cart it on to 
the field. Whatis he todo? The stables and cow houses and piggeries have 
to be regularly cleaned out, and if he piles it up in an open yard you know he 
will lose more than half of its value as a manure. So, if he is a sensibleman, 
he will have large pits dug. These pits must be made water-tight by lining 
them with concrete. This will prevent the drainings from the manure which 
is stacked in and above them from soaking into the soil. Then, a little way 
off, there should be underground tanks into which all the drainings are led, and 
these are occasionally pumped up into the manure heap, through which they 
again pass, collecting the valuable constituents of the urine as well as many of 
the soluble solids. The manure heap should be as solid as possible, and should 
_ always be kept moist. In the pit, fermentation will soon set in. 
FERMENTATION is a term used by chemists, and is derived from the Latin 
word fervere, to boil, and it is used to indicate the changes which compound 
organic substances undergo under certain conditions. You would not at 
resent be able to comprehend the exact nature of the various changes to which 
ermentation renders complex organic bodies liable. It is enough for you to 
know that it is caused by the action of the oxygen of the air on the manure. 
Tf no air were admitted to the heap there would be no fermentation, because 
the oxygen is necessary to produce it. The oxygen acts on the component 
parts of the manure, and these soon begin to heat. If you put your hand into 
a heap of manure which has been lately stacked you will find it is very warm, 
and, if the fermentation goes on rapidly, much heat will be developed. Now, 
what does this prove? It proves that the more air which can get into the 
mass of manure the more rapid will be the fermentation, but if the mass is 
trampled down solidly, either by the hoof of cattle or by any other means, the 
air cannot readily reach the interior of the heap, and so the fermentation will 
go on less rapidly. 
During the fermentation, the manure is always losing portions of its 
elements. Much of the non-nitrogenous organic matter passes off in the shape 
of carbonic acid and water. Other constituents also pass away by drainage (as 
ou have already learnt) and by evaporation. But the mineral matters—potash, 
ime, silica, soda, &c.—remain behind, provided that the manure heap is covered 
over, so as to prevent the rain soaking into it, and so dissolving some of these 
substances and carrying them away in the shape of drainage. I have now told 
you all that you need know at present about farmyard manure, but, before 
passing to xatural and artificial manures, I may tell you this : That whilst farm- 
yard manure possesses all the advantages described, still there are many reasons 
why, in certain cases, the natural or artificial manures would be preferable. It 
is all very well to apply stable manure to the land, but a large quantity is 
required, varying, of course, with the nature of the soil and of the crops it is 
intended to grow. But I will suppose, in order to give you some idea of the 
quantities required, that a turnip crop is to be sown ona sandy clay; 10 or 
12 tons or even 15 tons of farmyard manure are required per acre. See what a 
uantity would be required for a 20-acre field—from 200 to 300 tons; and even 
then a careful farmer would add to this about 400 ewt. of artificial manure per 
acre. 
Now, as two-thirds of farmyard manure is composed only of water, just 
consider what great quantities of a substance are carted on to the field which are 
practically useless, the fertilising matter bearing such a small proportion 
(one-third) to the bulk of the manure. Sometimes manure is scarce, 
at others plentiful. In the first place, it will be found to be too dear to use 
to any extent, because the resulting crop would probably not pay for 
the increased cost of fertilising it. So modern farmers have found it to their 
