1 Jan., 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 63 
as nitrate of soda, sulphate of ammonia, blood meal, chopped grass, cow-urine, 
horse-dung, cow-dung, various farm-yard manures; the results obtained were 
again similar, and all proved that dung possesses the peculiar action of not 
only preventing the organic nitrogen contained, for instance, in green manure, 
from becoming nitrified, and made available, but even to make the nitrogen 
already in a directly available form, as, for instance, nitrate of soda or sulphate 
of ammonia, partially useless. 
Wagner experimented also in pots containing soil without plants, and 
found that this actual loss of nitrogen was not due to its sinking lower into 
the soil or subsoil, but that the nitrogen really disappeared entirely from the 
pots. In all cases he proved that an addition of dung to soils containing 
nitrate of soda caused a partial disappearance of nitrogen, which loss was 
inereased by applying heavy dressings of dung. 
Numerous experiments made by Wagner, Maercker, Stutzer, Pfeiffer, 
Dietzel, and others proved that nitrogen was dissipated in its free form, and 
escaped into the air, and that this action is caused by the presence of certain 
bacteria found in dung. Dung sterilised with bisulphide of carbon only showed 
a slight start of denitrification after the lapse of four days, by which time all 
the nitrogen in soils containing unsterilised dung was destroyed. 
Maercker also made experiments substituting wheat straw for dung; and 
Wagner used rye straw, adding these finely chopped up to soils; and they found 
that both these substances, by their action on nitrate of soda, showed that they 
contain denitrifying organisms, or else produce very favourable conditions for 
the development of these bacteria. 
The next step of investigation was to find out how this denitrifying action 
of dung or farmyard manure, which acts quite similarly to dung alone, could 
be prevented. Both investigators showed that age and frequent turning of the 
heaps somewhat diminished the power of denitrification. Fresh dung in all 
cases acted much more vigorously than old dung; well-rotted farmyard manure 
possessed very little denitrifying power. 
These remarkable results obtained so far explain the failure of a large 
number of manuring field experiments made in England and elsewhere. It has 
frequently been found that addition of artificial manure to farmyard manure 
not only failed to produce an increase of the crop but very often resulted in 
a depression of the yield. Different explanations in such cases were given, but 
the experiments of Wagner and Maercker leave no doubt of the actual cause, 
and will prevent further waste of valuable nitrogenous manures by adding them 
to dung or farmyard manure. 
Further experiments also showed that an addition of superphosphates and 
of kainit to dung increases the denitrifying action considerably, and also 
counteracts the action of age and of the turning of the manure heaps. 
W. Somerville, in his article on the experiments of denitrification men- 
tioned above, shows that these last experiments seem to explain the failure of 
manuring experiments in Northumberland, where in 1893, when applying 12 
tons of dung per acre, the average yield of crops of swedes of nine farms was 
2ewt. per acre heavier, with 2% cwt. of superpkosphate, than when they applied 
5 ewt. of superphosphate to the same quantity of dung. 
In similar cases in nine farms in Cumberland, Durham, Northumberland, 
in 1895, where superphosphate or dissolved bones were used in conjunction 
with dressings of farmyard manure, the farms supplied with the largest quan- 
tities of phosphates gave the lightest crops. This increase of the denitrifying 
action might be attributed to a better development of the denitrifying bacteria 
in presence of an abundance of food containing phosphates and potash. 
The results so far obtained are of the greatest importance, and all 
agriculturists will await the publication of further experiments with the 
greatest interest. The experiments will no doubt be repeated by other 
investigators, and it will also be interesting to find out how our climate in 
Queensland will act on the denitrifying bacteria found in farmyard manure. 
