MANURING EXPERIMENTS WITH PADDY RICE. 



377 



m;ittcr. According t>o the researches previousl}' made by us, rice 

 plants consume 62 % of nitrogen from ammonium sulphate ; hence 

 its supjily from the natural sources (soil atmosphere and the water 

 of irrigation) would, on the same assumption, be represented by 

 the following figures : 



per plot. per tan. 



in 1889 11.56 grms. 13.9 kilogrms. 



1890 9.13 ,, ll.O 



1891 9/2 1 1.7 



189- 7-7' 9-3 



1893 8.00 9.6 



1894 9.76 ,, 1 1.7 



Thus the annual supply of nitrogen from the natural sources 

 was nearly constant and amounted on the average of the last five 

 years to 10.6 kilograms of ammoniacal nitrogen per tan, and would 

 suffice in round number for the production of 420 kilograms of 

 unhulled grains. 



Of the nitrogen applied as ammonium sulphate to the plots with 

 complete manure the following pro2:)ortions were absorbed b}- the 

 plants (in grms. per plot). 





1887 



1890 



1891 



1892 



1893 



1894 





13-37 



12.46 



11-93 



9.69 



9-63 



10.10 



In the crop grown w ithout 

















7-57 



743 



6.39 



5.09 



5-32 



6.27 



Taken up from the manure. 



5-83 



5 -03 



5-54 



4.60 



431 



383 





9.18 



9.18 



8-33 



8-33 



8.33 



8.33 



Absorbed percentage of the 

















63.0 



54.8 



66.5 



55-2 



51-7 



46.0 



Thus on the average of the six years' experiments performed 

 on the same plots, we find the assimilation factor for ammoniacal 

 nitrogen to be 56.2. 



(I) For the pro'luctioii of loo kilogniis. of imliullcd grain a supply of 2.53 kilogrms. of 

 aninioniacal nitrogen is rcquirL-rl, assxnniiig that tin.- soil is conipk-tclv free from nitrogen. 



