DIVISION OF CHEMISTRY 



251 



SESSIONAL PAPER No. 16 



the soil's potash, it performs a U3eful function in increasing the amount of this 

 constituent in a form available for crop use. It is this property that has made 

 it specially beneficial as a top dressing for clover, a crop that particularly responds 

 i i available potash. 



The application of land plaster is usually from 300 to 500 pounds per acre, 

 but larger dressings are sometimes found of benefit to heavy soils. 



Gypsum possesses the property of 'fixing' ammonia, and for this reason is largely 

 ed in stables and cow barns. Thus employed, the sprinkling or dusting of the 

 finely-ground material in the stalls servos to retain the nitrogen of the very readily 

 decomposable urine and incidentally to keep the atmosphere of the building clean 

 and sweet. It is this use of land plaster that we specially recommend, for by this 

 means the value of the resulting manure is enhanced without any hindrance to the 

 exercise of the other useful functions of this amendment subsequently in the soil. 



By reason of its property of flocculating clay, its application to heavy loams may 

 pi'ove of very considerable benefit in rendering them plastic and more open and friable. 



Similarly, an application of gypsum is valuable to lands affected by ' Black alkali.' 

 The sodium carbonate (sal. soda) which such soils contain not only acts directly as 

 a corrosive chemical, cutting into and eating away the plant tissues (especially at the 

 immediate surface of the soil, but its acts most injuriously on the physical condition 

 of the soil. All kinds of alkali have a tendency to destroy good tilth, but this is par- 

 ticularly marked in the case of black alkali. Soil, so affected, readily puddles, 

 becomes impervious to water and air and dries into hard, refractory masses. The 

 addition of land plaster converts the carbonate of soda into sulphate of soda — the 

 chief constituent of ' white alkali,' a milder form of alkali as regards vegetable life 

 and one with less effect on the physical condition of the soil. 



Commercial gypsum is somewhat variable in composition; poor samples may not 

 contain more than 65 per cent sulphate of lime, while high grades will reach 90 to 95 

 per cent. Analysis of some samples recently examined are as follows: — 



Analysis of Gypsum. 



Samples A, B, and C are from the Tobique River district, N.B., where gypsum 

 is largely quarried, and D is from Hants county, N.S. In addition to the vast 

 deposits found in Nova Scotia and New Brunswick, gypsum occurs in several locali- 

 ties in Ontario, and more particularly in the vicinity of Paris along the Grand river, 

 associated with dolomite rocks. 



WOOD ASHES. 



No. 12852. — This sample was taken from a heap of leached ashes from an old 

 potash works at Carleton Place, Ont. 



Analysis showed that the ashes had been very thoroughly leached, the percentage 

 of potash being only -022. While the fertilizing value of this residue must be very 

 small, its application would no doubt improve certain soils, so that, if cheaply 

 obtained, it might be found useful as an amendment. 



