T. D. MosscROP 181 



Pot ex'periments. 



Numerous pot experiments were also undertaken with the object 

 of demonstrating further that ammonia is the injurious substance 

 produced and of ascertaining what length of time must elapse before 

 the manure could be considered absolutely safe. Calcium cyanamide 

 was used in amounts considerably higher than would be adopted in 

 ordinary farm practice in order that the points aimed at might be more 

 clearly demonstrated. A mixture of (NH4)2 SO4 and CaO was used at 

 the same time to imitate as closely as possible the ammonia-producing 

 properties of calcium cyanamide. Since granular nitrolim has now 

 superseded the old powder form it is hardly worth while to give the 

 figures, but it may be remarked that the mixture of sulphate of ammonia 

 and quick-lime gave results which agreed remarkably with those from 

 calcium cyanamide and that the injurious action had disappeared eight 

 days after the manure had been applied to a moist soil. 



It would therefore appear probable that any injurious effect on 

 germination when calcium cyanamide is used is due to the formation 

 of free ammonia produced at first more rapidly than it can be adsorbed 

 by the soil. 



Any danger to non-oily seeds or those with a thin testa can be 

 avoided by applying the calcium cyanamide a week before sowing the 

 seeds. 



The author wishes to express his gratitude to Mr C. W. H. Greaves, 

 B.Sc, for his kindly help. 



{Received July 22nd, 1916.) 



