Gypsum as a Cane Fertiliser. 143 
matters, such as natural guano, oil-cake, fish, flesh, and 
blood meal, are employed to furnish nitrogen. Ammo- 
nium salts (sulphate and chloride) undergo the change 
to nitric acid without development of alkali, and, in 
their case, the aid of gypsum is not required. 
Some six or seven years ago, I pointed out most of the 
above facts to the Hon. Wm. Russell who, thereupon, 
with his usual enterprise, commenced experiments with 
gypsum upon his estates. He frequently expressed 
approval of the results to me, and, no doubt, to others, for 
the use of gypsum rapidly extended, and it now forms 
one of the regular imports of the colony. A knowledge 
of the functions of gypsum is, however, not possessed by 
many who employ it ; and expectations of largely in- 
creased yields of cane derived from its use have by no 
means been realised. As already explained, the manures 
usually employed contain sulphuric acid, so that gypsum 
used in addition to them is shorn of one of its chief 
advantages — that of supplying sulphur; also, when 
ammonium salts furnish the nitrogen required by the 
cane, the aid gypsum affords to nitrification is of no avail. 
Under such conditions, its only remaining property of 
importance, as far as at present known, is that of in- 
creasing the solvent action of water on clay, and this 
may be of limited utility. To give gypsum a fair chance, 
it should be tried with nitrogenous organic matter and 
insoluble phosphates, against the soluble manures now 
employed. Gypsum is the cheapest sulphate known, 
and if, by its aid, the usual manures could be supplanted 
by natural phosphates and nitrogenous matters, the 
saving to planters would be very great. 
