AND COLLEGE, PUSA, FOR 1914-15. 21 



found for samples of such gases were low, but unfortun 

 ately it is not possible to determine this ratio very pre- 

 cisely, and the difference actually found had to be referred 

 to probable error. In addition, subsequent considerations 

 of the quantities of nitrogen involved indicated that it is 

 doubtful if the question of the assimilation of this element 

 by the roots of Papilionacece can be solved by the N : A 

 ratio. 



Another question naturally arises, namely, whether other 

 gases than carbon dioxide or nitrogen are produced in 

 soils ? The gases of swamp rice-land include much hydro- 

 gen and methane, but the conditions are anaerobic and the 

 general opinion has been that in ordinary dry-land soils 

 such gases would not be produced. For example recent 

 samples of gases from Rothamsted soils 1 were found to be 

 free, or substantially free, from hydrogen and hydrocar- 

 bons. In some of the Pusa soil gases small, though well 

 defined, amounts of hydrogen were present. This was the 

 case particularly in the neighbourhood of the roots of crops, 

 san hemp, indigo, maize, and must be referred to bacterial 

 activity. In the same situations very large proportions, 

 16 to 20 per cent., of carbon dioxide, and low proportions — 

 2 to 4 per cent. — of oxygen were found. Such propor- 

 tions of these gases have not been met with elsewhere in the 

 neighbourhood of crops, but it is to be recollected that the 

 subject is one which has been hardly investigated hitherto 

 and indicates a very intensive activity of lower organisms 

 at least during the monsoon in India. 



The conditions during a period of rapid nitrate forma- 

 tion are again very interesting. When discussing the 

 drainage of rain water through soils, 2 evidence was adduc- 

 ed showing that intensive nitrification in the first few 

 inches of soil followed immediately after the first heavy 

 rain of the monsoon, in 1910; this occurred similarly in 

 1911 and 1914. During this process considerable amounts 

 of oxygen are required, and calculation showed that this 



1 Jour. Agric. Sci., VII, 4. 



a Mem. Dcpt. Agric. Ind., Chemical Series, vol. II, no. 2. 



