INSTITUTE, PISA, FOR 1910-17 105 



would have to be modified by cultivation, growth of green 

 manures, and addition of lime, before inoculation of the 

 soils could be attended with success. Defective nitrifi- 

 cation was found especially marked in certain soils from 

 Ranchi. 



Soil I did not form any nitrate at all either with 

 ammonium sulphate or cake, even on addition of lime. 

 Inoculation with Pusa soil produced nitrification of 75 per 

 cent, of ammonium sulphate and 90 per cent, of cake 

 nitrogen in six weeks' time. 



Soil II. This soil failed to produce any nitrate from 

 ammonium sulphate in six weeks, but nitrified 50 per cent, 

 of added cake nitrogen in this time, probably owing to the 

 introduction of nitrifiers with the cake. Inoculation with 

 Fusa soil resulted in complete nitrification of the ammonium 

 sulphate in six weeks and of the cake in four weeks. In 

 this soil addition of lime increased the rate of nitrification. 



Soil III. This soil nitrified 25 per cent, of added 

 ammonium sulphate nitrogen in four weeks; inoculation 

 produced complete nitrification (100 per cent.) in the same 

 time. 



Soil IV. 15 per cent, ammonium sulphate was nitrified 

 in six weeks; inoculation produced complete nitrification 

 in the same period. 



The addition of lime alone produced increased nitrifi- 

 cation in the soils II, III and IV, but had no effect on soil 

 I, nor was the addition of lime only in any case as effica- 

 cious as inoculation. 



Barley and maize germinated and grew well in these 

 soils for one week, after which growth stopped, the seed- 

 lings lost colour and all died after three weeks. 



The effect of toxins produced by bacterial action upon 

 nitrification was further studied. It was found that soil 

 plus organic matter incubated under semi -anaerobic condi- 

 tions gave a water extract which considerably lowered the 

 rate of nitrification when added to another soil. This 

 extract, on being made alkaline with caustic soda, gave 

 a white precipitate, containing more than 5 per cent. 



