016 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



When cyanamide is exposed to moist air or acted upon by water in 

 the soil it is converted into calcium carbonate, and ammonia ; but this 

 change appears to go on quite slowly under ordinary conditions, and in 

 our soil it is evident that the nitrogen is only rendered available com- 

 paratively slowly. LoHNis has shown that bacteria are concerned in 

 the process of converting the nitrogen into a form available for plants, 

 and it would appear that the changes that take place are by no means 

 simple. As we have seen above, the manure is comparable in its 

 action to ammonium sulphate, and, nitrogen for nitrogen, its value is 

 about the same. As it is not immediately available, it should be added 

 to the soil some three or four weeks before it is desired that its effects 

 should be seen; and in some cases, as is pointed out below, it is 

 advisable to add the manure to the soil three weeks before seed-sowing. 



The main difficulty in dealing with nitrolim lies in the fact that it 

 is so fine that the process of sowing is rather disagreeable, for it tends 

 to hang in the air. It has been submitted to a process for remedying 

 this, and this '* hydrated calcium cyanamide " is certainly more easy 

 to deal with in this direction, but for some reason or other it proved 

 far less readily available in our soil. 



Hall* has shown that though under ordinary circumstances 

 cyanamide may take water to some extent from the air, yet 

 the loss of nitrogen due to this cause is imperceptible (amounting 

 indeed to only 0.37 per cent., even when the nitrolim had gained 67 per 

 cent, in weight by absorbing water from saturated air). It is thus 

 practically as easy to store as sulphate of ammonia, and the probability 

 of loss is much less than from nitrate of soda and nitrate of lime. 



It is also shown in the same paper f that superphosphate may be 

 mixed with the cyanamide without loss of nitrogen, for any ammonia 

 set free is at once fixed by the superphosphate. | The mixture thus 

 produced is much easier to sow — in fact, as easy as any other artificial 

 manure. 



We have not noticed any harmful effects on seed germination either 

 in the garden or in pots following the use of calcium cyanamide, but 

 owing to the possible formation, in some soils, of an alleged poisonous 

 dicyanodiamide, it is best to apply the manure about three weeks before 

 planting or seed-sowing. 



The continued use of sulphate of ammonia tends to render the soil 

 acid and infertile, but the cyanamide contains caustic lime, and is 

 therefore more suitable for use on soil poor in lime than is sulphate 

 of ammonia. 



The continued use of nitrate of soda also has a harmful effect upon 

 clay soil, deflocculating the clay and making it very sticky. This 

 appears to be due to the fact that plants leave behind the soda of the 

 compound in the soil, where it combines with carbonic acid forming the 



* Journal of the Board of Agriculture, xiv. (1908), p. 652. 

 t p. 657. 



X The temperature rises considerably as the mixture is being made and 

 steam may begin to rise, but a little water added to the heap will keep the 

 temperature from rising so high as to render loss probable. 



