On the Behavior of Nitrate in Paddy Soils. 



BY 



G. DAIKUHARA AND T. IMASEKI. 



A great many manuring experiments carried out by different authors 

 prove that under certain conditions nitrate nitrogen is superior to ammonia 

 nitrogen, while under other conditions the reverse is true. It is to be 

 regretted, however, that the different conditions, as nature of soil, its 

 chemical composition and the character of the manure whether acidic or 

 alkaline or neutral, have not always been stated, since this knowledge would 

 have assisted much in recognising certain regularities. 



For those tropical and subtropical countries, in which agricultural 

 crops are raised in paddy soils or swamps, the question is also of vital 

 importarxe, which of the two sources of nitrogen would be the more favor- 

 able. The conditions in the paddy soil for nitrification and denitrification 

 are very different from those in the dry land soil. In the first place, the 

 transformation of ammonia into nitrite by the nitroso-bacterium is very much 

 depressed not only on account of less air penetrating into the soil, but also 

 on account of much organic matter, which is by no means oxidized as easily 

 as in dry land, and which according to Winograd^ky, depresses the action of 

 the nitrite-microbium ; but also for the nitrate-microbium the conditions are 

 very unfavorable, since its action is very much depressed by traces of 

 ammonia, Loehnis^^ however declared that only in the form of carbonate, 

 ammonia is injurious for the nitrate-microbium not in the form of neutral 

 salts. The paddy soil for rice culture in Japan has always been manured 

 chiefly with excrements, fish manure, oil cakes, and frequently green 

 manure ; superphosphate was applied occasionally as a mere supplement to 



i). Chem. Ztg. Repertorium 19:5, I, 5. 



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