EFFECT OF LIME UPON AVAILABILITY OF SOIL CONSTITUENTS. 65 



eight months in a dry state. The soil was well mixed and 

 a weighed portion shaken for a few minutes with nitrogen 

 free water in the proportion of 1 gram, of soil in 2 cc. water. 

 The extract having been filtered through porcelain under 

 pressure, 2 grammes purified "vegetable black" were added 

 to about 250 cc. and stirred for 20 minutes. The whole 

 was filtered again through a Pasteur candle, the filtrate 

 being then as a rule completely decolorised. In two cases 

 however the treatment with "black" had to be repeated 

 before a perfectly colourless solution was obtainable. 



The carbon used for this purpose was the ordinary 

 "vegetable black" of commerce, containing large quanti- 

 ties of paraffin oils. It was purified by heating to redness 

 in a covered crucible, and when cool lixiviating three times 

 with hot nitrogen free water. For the determination of 

 ammonium salts, portion of the filtrate from the soil after 

 decolorisation was nesslerised direct. The nitric nitrogen 

 was determined by the phenolsulphonic acid method and 

 the nitrous by the starch method. The results are given 

 below : — 



Nitrite nitrogen in parts per million of soil. 





Unlimed. 



Limed. 



Increase or Decrease * 



Clay ... 



... '4 



3*6 



... 



+ 3'2 



Loam... 



... -1 



2'0 



... 



+ 1-9 



Sand ... 



... nil 



•7 



... 



+ '7 





Nitrate nitrogen. 







Clay ... 



... 8*0 



5-0 



... 



- 3-0 



Loam... 



... 4*5 



4*5 



... 



... 



Sand ... 



... *2 



•4 



... 



+ '2 



The interesting point about the above figures is the large 

 increase in the proportion of nitrite nitrogen in the limed 

 soils. The total nitrogen as nitrite and nitrate has increased 

 in all cases, and the nitrate nitrogen has remained almost 

 stationary, except in the clay soil. It would not therefore 



E— Aug. 7, 1907. 



