594 
THE TROPICAL AGRICULTUW^/ ^: > [MAiicii 1. 1901. 
THE CHEAPEST FORM OF NITROGEN. 
One of the best autliorities on the value and 
action of sulphate of ammonia and nitrate of 
8oda on certain crops, Professor Warrington, 
writes to the quarterly Journal of the Royal 
Agricultural Society, England, as follows :— 
NITRATE BEST FOR LIMEY SOIL. 
On land containing no carbonate of calcium 
(or, in other words, lime), sulphate of ammonium 
cannot be profitably used as a manure, though 
nitrate of soda may. 
2. On land containing a large amount ot 
carbonute of calcium (lime) sulphate of ammonium 
•will seldom give its best result if applied as a 
top-dressing. On such land the proper course is 
to cover the manure with soil by the plough, 
and harrow it immediately after being distributed 
over the surface. 
3, Though sulphate of ammonium may often 
be successfully used as a top-dressing upon ordi- 
nary land, it gives its best return when it is 
ploughed or harrowed in before sowing the seed. 
It is thus specially suitable for application to 
spring corn and potatoes. 
4, Ammonium salts do not become available 
as plant food till they have become converted 
into nitrate of calcium. Thi^ nitrification will 
not take place in a dry soil, but in most arable 
soils it will speedily occur in showery weather. 
5. Nitrate of sodium, being immediately avail- 
able as plant food, and distributing itself in the 
soil more rapidly than the nitrate of calcium 
arising from the nitrification of sulphate ot 
ammonium, this manure is generally more suit- 
able for use as top-dressings to growing crops 
and for late applications. 
SULPHATE HAS MORE GRADUL EFFECT. 
The effect of sulphate of ammonium is 
6. _ - 
alvrays more gradual than that of nitrate of sodium, 
and is especially prolonged in soils containing 
little lime, and in old grass land, or when 
associated with organic m inures. This implies 
a more gradual or a longer continuance of growth 
in the crop receiving it, and results in some 
cases in a better quality of produce. 
7. The character of the climate or season 
frequently determines whether nitrate of sodium 
or sulphate of ammonium will be the more pro- 
fitable manure. In a dry season nitrate of 
sodium always gives a better return for the same 
quantity of nitrogen applied, while in a wet summer 
the advantage is frequently with the ammonium 
salt. This influence of climate is most clearly 
seen in the case of cereal crops, or on grass 
land ; it is less perceived in the case ef crops, 
like potatoes and mangels, which have a long 
period of growth. 
8. The greater crop frequently given by nitrate 
of sodium is in part due to the soda which it 
smpplies, the soda acting beneficially both in the 
soil and in the plant. 
PRODUCE YIELDED, 
9. The produce yielded by sulphate of am- 
monium is more dependent on the presence in 
the soil of an abundant supply of cinereal plant 
food than is the case when nitrate of sodium 
is employed. Kainit is an excellent addition to 
sulphate of ammonium. 
10. On an average of ten series of field ex- 
periments with cereal crops, continued throughout 
many years,' in which equal quaitjtities of nitiogen 
in the forms of niirate of sodiniii and ammonium 
salts were applied to soils - well supplied with 
potash, soda, and phosphates, the average return 
in corn was 9.S by ammonium salts for lOD by 
nitrate of sodium, and in straw 79 by ammonia 
for 100 by nitrate. The return in corn is thus 
not very different by two manures, but the re* 
aurn in straw is considerably larger when nitrate 
of sodium is used. The quality of the corn wa« 
a little better where ammonium salts had been 
employed. 
SOME FIELD EXPERIMENTS. 
11. In three series of field experiments on grass 
hay, conducted in the manner thus described, 
the average return by ammonimn salts was 85 
per cent, of that given by nitrate of sodium, 
when the first cutting of hay was alone considered. 
When the second cutting of hay was included, 
the return by ammonium salts was in two series 
of experiments 88 per cent, of that given by the 
nitrate. 
12. In the first ten yeais of the Rothamsted 
experimeuDs with potatoes, the produce by am- 
monium salts was on an average fully equal 
to th.'it yielded by nitrate of sodium. No dung 
was used, but alkali salts and superphosphate 
were applied. 
13. Tiie weight of mangel roots yielded by 
ammonium salts during seventeen years at 
Rothamsted was on an average only 76 per cent, 
of that yielded by nitrate ot sodium, but when 
the superior quality of the roots grown by am- 
monium salts is taken into account, the return 
by the ammonia is probably 82 per cent, of 
that given by the nitrate. No dung was used, 
but alkaki salts and superphosphate were applied. 
FARM EXPERIMENTS IN SCOTLAND. 
14. The farm experiments made on turnips in 
Scotland and the north of England, with small 
quantites of sulphate of ammonium and nitrate 
of sodium generally do not show any consider- 
able difference in the effect of these two manures. 
15. Sulphate of ammonium of average quality 
will contain 24J per cent, of ammonia. Nitrate 
of sodium of 95 per cetit. purity will contain 
nitrogen equivalent to 19 per cent, of ammonia ; 
19 lb. of sulphate of ammonium will thus supply 
as much nitrogen as 24| lb. of nitrate of sodium. 
16. If the nitrogen in the two manures pro- 
duced the same effect on crops, their money 
value would be determined simply by rheir con- 
tents in nitrogen. Thus when nitrate of sodium 
was £8 a ton, sulphate of ammonium would be 
worth £10 6s. Under various circumstances already 
described, ihe nitrogen in sulphate of ammonium 
is sometimes as effective as bhat in nitrate of 
sodium, and sometimes gives a smaller return. 
— Queensland Agricultural Journal. 
G. Tipping's 
impression of 
" FOXY COFFEE, 
To Editor " Planting Opinion 
Sir, — With reference to Mr, P. 
query 7'e " Foxy Coffee " in your 
the 5th instant, I think he will find the follow- 
ing information of some use. Speaking on the 
subject at the U. P. A. S. I. Me;ting in 1899, 
Mr. Graham Anderson, C.I.E., sai 1 : — " This term 
("foxy") denotes a reddy-brown appearance of 
the seed caused by the adhesion ot the silver 
skin into which the colouring matter contained 
