Gypsum as a Cane Fertiliser. 137 
probably carbonate, so that admixture with gypsum 
would facilitate their nitrification. WARINGTON, in his 
paper on the subject, states that " The action of gypsum 
in these few experiments is quite in accordance with the 
observations of others. Thus, PlCHARD, (Ann. Agro- 
nomy 1884, p. 302), experimenting on the nitrifica- 
tion of earth-nut cake mixed with sand, found that by 
far the largest amount of nitric acid was produced when 
gypsum was added to the mixture ; he supposes, how- 
ever, that the sulphate of calcium had acted simply as 
an oxidising agent, and that its effect was due ' a sa 
facilite d'etre deoxyde au contacl des matieres organ- 
ique et reoxyde au contact de I'airJ JOULIE, also, in 
his experiments on the loss of nitrogen during the fer- 
mentation of farm-yard manure {ibid, p. 289), found a 
formation of nitric acid only in those cases in which 
gypsum had been added to the mixture." WARINGTON 
concludes by saying that : " In agriculture, the activity 
of dressings of farm-yard manure would probably be 
increased by the addition of gypsum to the soil."* 
Gypsum therefore is a many-sided fertiliser, and its 
functions as at present ascertained may be summarised 
as follows : — 
I. It acts as a plant-food per se by supplying lime or 
sulphuric acid or both. 
II. It is capable of absorbing and fixing ammonium 
carbonate from the air or rain, although its action in this 
respect is probably superfluous. 
III. It renders the plant constituents of soil more 
soluble in water. 
IV. It promotes nitrification. 
* Journ. Chem. Soc. Trans. 1885, 758. 
S 
