420 QUEENSLAND AGRICULTURAL JOURNAL. {1 Jone, 1899.- 
in the soil. The sourness is due chiefly to acids secreted by the roots of plants 
or produced by the decay of organic matter, and these are neutralised by lime, 
This is generally understood; but the way in which the oxidation of organic 
matter is effected by means of lime has only recently been fully discovered. It 
was formerly supposed that the oxidation of organic matter was simply a direct 
union of it with the oxygen of the air; but it is now known that the action is 
brought about through the instrumentality of minute fungi, which increase by 
subdivision. These vegetable bacteria live upon the organic matter in the soil, 
oxidising it, and converting it into acid products, which, in excess, injure the 
vitality of the bacteria, and may even destroy them, In order that they may 
flourish, some base must be present to neutralise these acids, and lime supplies 
the want. Similarly, lime is of great value to the nitrifying organisms, which 
perform a vastly important function in the soil, neutralising the acids which 
they form. In excess, however, lime kills these useful bacteria, and this explains 
the ill effects of the too liberal or frequent application of the alkali. Again, 
lime is valuable to the organisms, which account for the assimilation of 
atmospheric nitrogen in connection with leguminous crops, for neutralising 
inorganic acids in the soil, for improving the physical condition of clay, and for 
liberating potash held in combination with silica. Some soils, however, contain 
an abundance of lime, and farmers have to be guided by certain signs as 
indicating the need of it in other soils, such as the growth of mosses and sour 
grasses in pasture. An ordinary analysis is not always a sure guide as to 
whether a soil needs lime or not, as it is beneficial in some soils which show no 
lack of this material; but Dr. Aitken calls attention to a method of roughly 
ascertaining the proportion of available lime in a soil, discovered by Dr. 
Holleman, which can be applied by chemists to whom samples of soils are 
submitted. 
ANIMAL EXCRETA. 
THEIR MANURIAL VALUE. 
Cow-pune is the most abundant and the least valuable in its composition of 
the animal manures. In Johnston Cameron’s “Elements of Agricultural 
Chemistry,” it is stated that it decomposes slowly, giving out but little heat ; 
hence it is said to be a cold manure. This is quite correct, for manures such ag 
horse-dung, which decompose rapidly in the soil, warm the latter. Decomposi- 
tion in such cases is really a slow combustion. 
Horse-dung is more valuable than cow-dung. It contains less water, is not 
so coherent, and does not form during its decomposition an unctuous mass such 
as cow-dung does. Horse-dung decomposes rapidly, and is therefore a hot 
manure. It is a useful addition to cow-dung, as it renders the latter more 
friable, whereby it can be more equabl y distributed throughout the soil. 
Sheep-dung decomposes more rapidly than cow-dung, and not so quickly as 
horse-dung. It is richer in solid matters than the former. 
Pig-dung.—The pig being almost an omniyerous animal, its excrements 
vary in composition according to the nature of its foods. Its dung is soft and 
compact, and it decomposes slowly. It is one of the richest kinds of animal 
manure; but it is alleged that, when used alone as a manure, it gives a dis- 
agreeable flavour to roots. On the Continent, pig-dung is largely applied to 
the hemp crop. 
: COMPOSITION OF ANIMAL FACES, 
One hundred parts of each contain— 
Pig. Cow. Sheep. Horse. 
Water ex xt eaalisieles 82°45 5647 77°25 
Solid matters eee aay PRBS 17°55 43°53 2275 
—_—_—_. 
10000 =100:00 =100:00 ~—-100-00 
Ass cr ee 850 GY BBY B04 
