12 («■ Daikuhara and T. Iinaaekl. 



flasks, especially with the sandy soil, somewhat less so with the clayey soil 

 and still weaker in the humus soil. With the humus and sandy soils a 

 little sodium acetate was added to accelerate the bacterial action, after the 

 nitrite reaction had disappeared. Thus again a gradual increase of the 

 nitrite was observed and finally it reached a concentration of 0,1% resp. 

 £),o$% nitrite 12 days after that addition, much foam being developed. No 

 -ammonia was observed in this case. 



Further to ascertain whether the reduction of nitrate wis due to 

 bacteria, the mixture of soil and the nitrate solution mentioned above, was 

 sterilized with steam, with chloroform and with mercuric chloride. Oc- 

 •casional testing for nitrite showed the absense of nitrite even after several 

 weeks. This proves clearly that the reduction of nitrate in soils in the 

 ipaddy state certainly is due to the action of denitrifying organisms. 



LABORATORY EXPERIMENT. II. 



Since in Japan much organic manure is commonly used in the paddy 

 field, it is of vital importance to observe the influence of organic matter 

 upon the reduction of nitrate in the paddy state. 150 cc. of the following 

 nitrate solution was mixed with 100 g of air dry soil and kept at a 

 temperature of 30-3 2°C. It was found that all the nitrate was reduced 

 •entirely after 48 hours. 



Na-acetate (or glycerine) 0.5 % 



NaNOs 0.2 % 



K2HPO4 0.2 % 



MgS04 + 7H20 .' ... 0.02% 



On April 15, 1905, 100 g of the three different soils above mentioned 

 were mixed with the same nitrate solution containing glycerine and kept at 

 'room temperature (r3-26''C). The occasional tests for nitrite and ammonia 

 ^ave the following results : 



