1 1 6 Decoinposition of Cyanainide and Dici/anodiamide 



average results of the field trials in Great Britain, which show that, 

 when ammonium sulphate is expressed as 100, nitrolim is equal to 

 94-4. These results include some cases in which nitrolim delayed 

 germination, or caused a temporary check to the crop, where applied 

 wrongly as a top dressing. 



The pot experiments, on the other hand, demonstrated conclusively 

 the harmful effect of dicyanodiamide. Even in the maximum dressing, 

 however, it did not affect germination. Its toxicity was first revealed a 

 few days after germination by the white tips or margins of the cotyledons. 

 The other leaves became similarly affected in turn. With small amounts 

 the injury was confined to the extreme tips of the leaves and the plants 

 showed more or less normal growth. The larger dressings, however, 

 caused a progressive withering of the leaves from the tips downwards 

 and subsequently depressed the growth below that of the controls, or 

 finally, in sufficient quantity, killed the plants. The toxic effect was 

 slightly more pronounced in the light Woburn than in the heavy 

 Rothamsted soil. 



In combination with cyanamide the greater the proportion of 

 dicyanodiamide nitrogen, the lower the yield. Where a mixture of 

 cyanamide and dicyanodiamide was used in the proportion of one part 

 cyanamide and three parts dicyanodiamide, the depressing effect of 

 the dicyanodiamide more than counterbalanced the beneficial effect of 

 the cyanamide. 



Similar results were obtained in the field trials (p. 133). 



The pot experimental results with mustard and barley were : 



It is interesting to note the high percentages of nitrogen recovered 

 in the mustard crop from the ammonium sulphate and pure cyanamide 

 dressings, considering that the roots were not included in the analvsis. 



