MANURIiXG EXrr.RIMENTS WITH PADDY RICE. 



b\- US, rice plants can assimilate 50 % of potash from its soluble 

 salt ; hence the supply from the natural sources would be 

 equal to the following quantities of potash having the same 

 manurial value as that of the soluble salt. 



l)er frame. per tan. 



in 1889 9.18 grms. no kilogrms. 



1890 7.34 ,, 8.8 



1891 5.78 6.9 



1892 6.02 7.2 



1893 4.80 5.8 



1894 7.30 ,, 8.8 



Thus the annual supi)l\- of assimilable potash amounted on the 

 average of the results of the last five years' experiments, to 7.5 

 kilogrms. per tan. This quantity is sufficient for the production of 

 5.70 kilogrms. of unhulled grain. ^'^ 



By the method explained above we can easily calculate, as O. 

 Kellner^^^ has proposed, the figures which give reliable informations 

 on the requirement of fertilizer by the soil. Thus according to the 

 experiments hitherto made we have found that for the production of 

 100 kilogrms. of unhulled rice grain, 2.53 kilogrms. of nitrogen in the 

 form of ammonium salt, 1.42 kilogrms. of phosphoric acid as super- 

 phosphate and 1. 3 1 kilogrms. of potash as a salt arc required. 

 Now we found that after six experimental years there were still 

 present in the soil 1.17 kilogrms. of nitrogen, 5.84 kilogrms. of 

 [)hosphoric acid and 8.8 kilogrms. of potash. Hence for the pro- 

 duction of 500 kilogrms. of unhulled grain there must be supplied 

 the following quantities of the nutriments : 



The quantities of the nutri- Xitiogcn. fhosphoric acid. Potash, 

 ments necessary for the pro- 

 duction of 500 kilogrms. of 



unhulled grain 12.7 kilogrs. 7.1 kilogrs. 6.6kilogrs. 



The quantities of the nutri- 

 ments present in the soil ... 1 1 .7 5.8 8.8 



The minimum quantities of 

 the nutriments to be applied 



as manure i.o 1.3 — 



(1) For the production of 100 kilotjrms. of unhulled grain a supply of 1.31 kilogrms. of 

 the assimilable potash is necessary. In this calculation, the results of the experiments of the 

 first year have been omitted, since in that year there was a liberal supply of soil potash, in 

 consequence of which rice plants might have consumed this nutriment over and above what 

 was absolutely necessary for the production of organic matter. 



(2) Die landwirthschaflliche \'^ersuclisstationc-ii 1892, p. 302. 



