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3 G. Dalktiliara and T. Imaseki. 



those manures. These conditions being favorable for denitrificatlon might 

 lead to much loss, if nitrate were applied as a part of the nitrogen manure. 

 Until recently however no experiments with plants cultivated in swamps 

 have been made. It was Prof. M. Nagaoka^^ who first carried out a number 

 of careful experiments with plants cultivated by Japanese farmers in swamps 

 as viz. rice, arrowhead {Sag-itiaria sagittaefolia) and Jiincus cffusiis. 

 Sagittaria bulbs are used as food and Jiincus is used for the manufacture of 

 rugs. The Plants manured with nitrate remained pale i:i color and small in 

 size. With rice the yield of the nitrate plants was only in one case a little 

 above that of the control plants, in most cases, however, far below ; in 

 one case, where the soil received no lime and the ratio of 150 Kg N 

 p. ha., the yield of the nitrate plants fell to about 2^ of that of ammonia 

 plants. 



With Juncus the yield of the nitrate plants varied from 4,7-665^ ot the 

 ammonia plants provided with equal doses of nitrogen. For Sagittaria the 

 result was still more unfavorable. It is very remarkable that with Juncus 

 the harvest of the nitrate phnts diminished gradually with the increased 

 applications of the nitrate. 



Some experiments^^ carried out by one of us (Daikuhara) with rice 

 plants in sand culture showed that the availability of nitrate is 42% of that of 

 ammonia nitrogen. The average ratio for the manurial value of ammonia 

 nitrogen to that of nitrate nitrogen calculated from different results of 

 experiments carried out in our central and branch Stations during the last 

 few years is 100 : 47. 



As to the reason why the paddy plants cannot utilize nitrate nitrogen 

 so well as ammonia nitrogen, Nagaoka^* has proposed the two following 

 factors : 



i). Bull. College of Agric, Imp. University, Tokyo, Vol. VI., No. 3. 



2). This Bulletin Vol. I., No. r. 



3). Nagaoka has also ascribed the pale yellowish color of the nitrate p'ants to the physiological 

 influence of accumulated nitrate, but according to our observations the pale yellowish color appears 

 in the first period of growth, 2-3 weeks after the application of nitrate, and recovers afterwards. 

 It is very probable, therefore, due to the poisonous action of nitrite formed by the reducing action 

 of certain bicteria. 



