20 REPORT OF THE AGRICULTURAL RESEARCH INSTITUTE 



gas were being produced from organic matters or if it were 

 being assimilated by a plant, its ratio to the rarer elements 

 would be altered. The estimation of the proportion of 

 argon in soil gases offered a probable solution of some of the 

 above indicated questions. Argon takes no part in animal 

 or vegetable economy, and except for very slight possible 

 alterations due to diffusion, its ratio to oxygen and nitrogen 

 in the soil would be the same as that in the air. unless these 

 latter gases were absorbed or liberated during biochemical 

 change. The atmosphere contains only 0-93 per cent. 

 A against about 79 per cent. N, and since the accuracy of 

 the estimation of the one depends on that of the other, the 

 probable error in the ratio is not inconsiderable, but 

 nevertheless as an aid to the examination of soil gases, the 

 argon determination has proved of great use. 



Mr. Harrison very kindly sent me samples of the gases 

 obtained from paddy lands and the result of the analyses 

 was to show quite conclusively that nitrogen gas is liberated 

 in these lands from the organic matters. The N : A ratio 

 in atmospheric air is 83, whilst those found in the paddy 

 land gas varied from 92 to 98. Moreover it has to be 

 realized that the outside air is so perfectly excluded that, 

 apart from any nitrogen evolution in the soil, the nitrogen 

 and argon in these gases are largely derived from the 

 dissolved gases in the water, in which the N : A ratio is 33. 

 Hence the conclusion was admissible that a high propor- 

 tion of the nitrogen in these gases is derived from the 

 decomposition of the organic matters. 



In other cases the N : A ratio has not proved so service- 

 able as was at first hoped. The assimilation of nitrogen 

 gas by Papilionacece is a case in point. It is usually 

 assumed that the assimilation, by these plants of a part of 

 their nitrogen is effected indirectly by the agency of the 

 bacterium, Bac. radicicola in the root nodules, but the 

 assumption lacks direct experimental proof. Allowing the 

 truth of the assumption, then the N : A ratio would fall in 

 the gases present in the neighbourhood of the roots of such 

 plants. As a matter of fact nearly all the N : A ratios 



