576 
Supplement to the “ Tropical Agriculturist: 
[Feb. 1. 1898. 
DENITEIPICATION-THE OTHER SIDE. 
In tlie November number of the Ayricultvral 
Magazine there was ])ublislied a resume of nn 
article by Dr. Somerville on “ Denitrification." 
In the Mark Lane Express Almanac appears 
a contribulion from the iren of Dr. Bernard Dyer, 
in which that well-known authority ' critically 
examines the experimenls referred to in Dr. 
Somerville’s article. Referring to the work of the 
German investigators the waiter .<=ays : — 
“ The discovery may throw some light on the 
failure of artificials in some English Agri- 
cultural experiments to make any material or 
satisfactory addition to the produce obtained by 
dressings of dung, and there is no reasonable 
doubt that dung, under some circumstances, may 
be a wasteful instead of an economical addition 
to the soil ; nevertheless, the vast mass of 
practical experience of good effects following the 
use of dung makes it difficult to believe that 
the circum.stauces under which its action is 
baneful rather than beneficial to the farmer are 
the frequent circumstances of every day farming, 
and it is impos.sihle to avoid a hope that it 
may eventually be jiroved that the conditions 
in which these ill-effects arise r;e exceptional 
rather tlian general in piactiual field work 
German investigators are, however, thorough 
in their work, and no doubt the subject will 
continue to receive attention until its practical 
side is completely elucidated.’’ 
In 1891 Dr. Dyer and Mr. Rosling carried on 
some experiments in the manuring of cabbages. 
Dung alone gave an increa.se of 5 tons 13 cwt. 
per acre over the unmanuied crop. The yield was 
somewhat decreased where superphosphate alone 
W’as added to dung. Where nitrate of soda and 
dung were used the increase rose from 5 tons 
18 cwt. to 7 tons 6 cwt. When “ super ’’ and 
nitrate, either with or without salt, were both 
added to dung, there was a further increase 
over the dunged crop up to nearly 7 tons per 
acre. Guano when added to dung raised the 
increase from 6 tons 13 cwts. to 7 tons 
16 cwt.; two cwt. of nitrate added to dung and 
guano gave 1 5 tons more, while the addition 
of 2 cwt. more of nitrate gave still another 
ton of cabbages, the addition of salt to the 
dung, guano and nitrate making the increase 
2 tons greater, bringing it up to 12 tons 8 cwt. 
or nearly 7 tons more increase than was made 
by dung alone. 
Here then, in these experiments, the dung 
alone gave a substantial increase, which w’as 
more than doubled bj^ the judicious addition of 
artificials. It will furtlier be observed that there 
was no indication of the alleged depressing 
action of dung, nor of the intensifying of that 
action by superphosphate. Dr. Dyer gives the 
details of another series of experiments carried 
out in 1892, and concludes by saying: Here 
again we have chemical fertilizers working well 
by themselves, and dung working well by itself, 
with a largely increased advantage from the use 
of both together. 
Again, Dr. Dyer refers to an extensive series 
of experiments conducted by himself and Mr. 
Shrivell in Kent, wdiere the dung used was by 
DO means well-rotted stable manure, the result 
of which were that dung wnth phosphates and 
nitrate of soda j)roduced 1^ tons more of crop 
than the artificials without dung. 
These experiments were extended to a large 
variety of crops, and their general result was 
to ,«how that though a full dose of artificials 
produce.s better results than dung alone, yet the 
heaviest crops are most frequently grown w'here 
a moderate do.se of dung is used in addition 
to a liberal supply of artificials. It undoubtedly, 
how-ever, occasionally happens, says Dr. Dyer, 
that the plot heavily manured with artificials 
without dung beats the similarly manured plot 
to which dung also is applied, 'hut he points 
out that this is not generally the case. The 
chief ecconomical value of dung, as pointed out, 
lies in its mechanical action which, however, 
says the writer would he too de.arly purchased 
if dung has the destructive action on nitrate 
wdiich the German experiments attribute to it. 
Dr. Dyer honestly confesses that the results 
of the experiments detailed by him do not go 
to prove that dung is not destructive to nitrates 
hut that they indicate that the destruction, under 
at any rate some practical condition.s, is not 
large enough to render the addition of artificials 
to dung otherwise than advantageous and 
economical, 
With reference to the action of phosiihates 
and kainit in intensifying the denitrifying action 
of dung. Dr. Dyer points out that this is directly 
contrary to the experience of Holdefleiss of 
Proskau (given in the R. A. S. E. Journal for 
December, 1893) who found that a dung heap 
of 6 tons, left uncovered, lost in six months 
23 per cent nitrogen, and that when 6 per cent 
of kainit was introduced into a similar liea]), 
no nitrogen wuas lost. When phosphatic gypsum 
was used there was again nu loss of nitrogen, 
Holdefleiss al.«o found that the dung treated with 
potash salts produced double the increase of 
potatoes jiroduced by pure dung; while the dung 
treated with phosph.atic gypsum produced four 
times the increase. 
In an experiment with wheat, dung with 
phosphates gave an increase of grain 2| times 
as large as that given by dung alone, while 
dung with potash salts gave nearly three times 
the increase. 
Dr. Dyer thus concludes his practical article; 
Next to the great discovery of the special source 
of nitrogen in leguminous crops, the subject 
is one of the most interesting, as well as the 
most economically important, that agricultural 
chemists have attacked in modern times, and 
it is so complicated that it will probably’ hold 
the field for some time to come. Meanwhile 
vye are all indebted to Dr. Somerville for his 
timely, if somewhat disconcerting article. 
OCCASIONAL NOTES. 
The ]uize offered for the best milch cow at the 
last Horse and Cattle Show held on the Havelock 
Race-courae was aw^arded to the Government 
Dairy e “Alerry Girl. ” 
The School of Agriculture re-opened after the 
Christmas holidays on the 15th January. The 
