55 



XLIV. G. A. CowiE. " Decomposition of Cyanamide and 

 Dicyanodianiide in the 6'oi7. " Journal of Agricul- 

 tural Science, 1919. Vol. IX. pp. 113-136. 



In field practice calcium cyanamide, commonly known in this 

 country as nitrolim, has varied considerably in effectiveness. On 

 the a\erag-e of all field trials in the United Kingdom, when the 

 effect of nitrate of soda is taken as 100, that of sulphate of 

 ammonia is 97 and of cyanamide 90. But the cyanamide results 

 fall as low as 26 and rise as high as 238. It is now shown that 

 cyanamide under certain conditions contains another substance, 

 dicyanodiamide, which is poisonous not only to plants but to the 

 nitrifying organisms also. It is less toxic towards other bacteria, 

 however, and has little effect on the numbers developing en 

 gelatine plates, or on the rate and extent of the decomposition of 

 dried blood. Nor does it reduce the rate of production of ammonia 

 from c}anamide. In its presence ammonia accumulates in the 

 soil, and the normal oxidation to nitrate does not take place. 



Dicyanodiamide, therefore, not only injures the plant but cuts 

 oft' the supply of nitrate, substituting instead ammonia, which in 

 most cases is less useful, and in some cases directly harmful to the 

 crop. The conditions under which it is formed are known and, 

 fortunately, it can be avoided. 



XLV. E. j. Russell. " Faynixard Manure : its Making 

 and its Use." Journal of the Farmers' Club, 1920. 

 89-106 ; also in Journal of the Ministry of Agricul- 

 ture, 1920. Vol. XXVII. pp. 444-449. 



A summary specially prepared for farmers of the results of 

 the recent Rothamsted experiments with farmyard manure (see 

 Report 1915-17 for details). 



XLV I. E, J. Russell. " The hifluence of Farmyard 

 Manure on the Clover Crop." Journal of the Board 

 of Agriculture, 1919. Vol. XXVI. pp. 124-130. 



Remarkably few field experiments have been made with the 

 clover crop, but a series recently begun at Rothamsted indicate an 

 unexpected effect on farmyard manure in increasing the yield. 

 Where artificials had been applied to the preceding crops the yield 

 was 19J cwt. per acre, but where farmyard manure was used it was 

 32-35 cwt. No explanation can be offered with certainty, but the 

 problem is under investigation in the laboratory. 



XLVIl. E. J. Russell. " The Agricultural Value of 

 Organic Manures." Journal of the Board of Agri- 

 culture, 1919. Vol. XXVI. pp. 228-247. 

 When Peruvian guano, rape cake and shoddy are compared 

 on the basis of equal amounts of nitrogen per acre : — 



Peruvian guano proved the most effective, especially in the 

 year of application. 



Rape cake came next. 



Shoddy by a small margin came last in its year of application. 



Numerically, the values were : — 



l^eruvian guano . , .100 



Rape cake . . . .91 

 Shoddy . . . . 88 . 



