«4 



Ci. Dtikuliaia an<1 T. Iinaseki. 



solution of the following composition and kept at room temperature 

 (20-3 2°C) with occasional testing for nitrite and nitrate : 



NaNOg 2.C0 g'\ 



K,HPO, 0.20 gP°'"^^ '" 



MgSO, + 7H.O coagj ^5° cc. H.O. 



After 24 hours a stronger nitrite reaction was observed in (i) than in 

 (2) (0,05% resp. 0,005^ nitrite as KNO^,). The maximum amount of 

 nitrite was attained after 3 days with (r) and af:er 5 days with (2) but after 

 4 resp. 7 weeks all the nitrate was reduced. Thus we see that fresh rape 

 •cake favors denitrification much more than glycerine. 



(b). Some rape cake and soy been cake were left to putref)' in a warm 

 place with a moderate supply of water and after 2 months rottening, samples 

 were dried and finely pulverized. Two g of each, fresh cakes and the same 

 amount of dry matter of the rotten cakes were mixed respectively with 

 100 g of air dry soil and 150 cc. of the foUo'.ving nitrate solution, and kept 

 at 25°C. 



NaNOo 1.75 g) 



^, ^^ f dissolved in 



K2HPO4 0.50 gV 



,, „_ I 150 cc. of HvO. 



MgSO^ + yHvO 0.05 g) ^ 



The tests showed that with fresh rape cake all the nitrate' was reduced 

 after 2 weeks, but with rotten cake much nitrate was still present even 

 after 10 weeks. With soy been cake which is poorer in carbohydrates 

 and richer in protein the difference was much smaller and the nitrate was 

 reduced entirely in the case of fresh and rotten cake after 10 and 12 days 

 respectively. 



Thus we see that the fresh rape cakes favor denitrification much more 

 than the rotten. 



LABORATORY EXPERIMENT. IV. 



To see the effect of inoculation of denitrifying organisms, pure cultured, 

 into the soil in the paddy state, the following 3 organisms were selected : 



