1910.] Experiments with Calcium Cvanamide. 



135 



to the presence of this substance in the cyanamide. In the 

 experiments at Rothamsted (Journal, March, 1910, p. 1006), 

 on the other hand, the lime gave it no advantage. 



These conclusions are confirmed by the experiments carried 

 out in Scotland by Mr. James Hendrick * under ordinary 

 farming conditions over the four years 1905-8 on fields which 

 were being cropped with cereals in the ordinary way. 



The plan adopted was to have a series of plots manured 

 with equal amounts of nitrogen, but one plot got the nitrogen 

 in the form of nitrate of soda, another in the form of sulphate 

 of ammonia, another as nitrate of lime, and others as cyan- 

 amide. All the plots received equally a dressing of a phos- 

 phatic and of a potassic manure, to ensure that the crops 

 on none of the plots suffered from any deficiency of these 

 two essential manurial constituents. There were two other 

 plots in every case, one of which received no manure while 

 the other received a dressing of the phosphatic and potassic 

 manures only. The first of these served to show the capacity 

 of the soil without any manure and the other its capacity 

 without any nitrogenous manure but with a liberal supply of 

 phosphatic and potassic manure. 



The manures used were all analysed, and the amounts of 

 the different nitrogenous manures applied were calculated 

 from the analysis so as to supply an equal dressing of nitrogen 

 per acre to each plot. The quantity was approximately equal 

 to 1 cwt. of sulphate of ammonia. The percentages of 

 nitrogen were as follows : — 



Percentage of nitrogen. 





1905. 



1906. 



1907. 



Nitrate of Soda 



16 12 



16*14 



i5'54 



Sulphate of Ammonia 



2028 



20 '4 1 



20-35 



Calcium Cyanamide... 



26-50 



1 8 -20 



1977 



Nitrate of Lime 





9 60 



12-14 



1908. 



The general average of thirteen experiments carried out in 

 three different seasons shows how little grain crops are 

 increased by a supply of phosphates and potash alone. Plot 2 

 only gave an average increase of 64 lb. of grain and ij cwt. 

 of straw and chaff as compared with Plot 1, On the other 

 hand, the addition of any of the four nitrogenous manures 

 used gave a large increase in both grain and straw. The 



* Aberdeen and North of Scotland College of Agric, Bulletin, No. 13. 



