28 SCTENTTFTC REPORTS OF THE AGRICULTURAL "RESEARCH 



bination occurs, of such intensity that the absence of any 

 large quantity of these gases from the atmosphere in paddy 

 soils is accounted for. Incidentally distinct evidence has 

 been obtained to show that marsh gas can be produced by 

 a combination of these two gases under biological in- 

 fluences. 



This phenomenon offers a reasonable explanation to 

 account for the accumulation of nitrogen gas in these soils 

 without the necessity of putting forward the theory of the 

 presence of peculiar types of fermentation, and it also has 

 a considerable bearing on the question of lime conservation. 

 The important fact has also been obtained that this reaction 

 between carbon dioxide and hydrogen is not peculiar to 

 paddy soils, but that it can be induced in dry soils with the 

 utmost ease when the conditions are approximately anae- 

 robic in character. 



This investigation is practically completed and the 

 results are being prepared for publication. 



(b) "Bara" Soils. At the instance of the late Dr. 

 Barnes, a series of pot-culture experiments were instituted 

 with the object of testing the growth which could be 

 induced in these sterile soils by washing out the salts 

 present with ordinary water. The water used in this 

 instance was the ordinary well water of Pusa with the 

 result that germination was practically entirely inhibited. 



The washed soils were, therefore, subjected to a careful 

 examination, and it became evident that the bicarbonate 

 of lime in the water had brought about a reaction leading 

 to the production of alkaline carbonate in the soil. The 

 soil experimented with originally contained a comparative- 

 ly small amount of alkaline carbonate and a considerable 

 proportion of sulphates and chlorides, whereas, after the 

 washing process, the sulphates and chlorides were reduced 

 in amount but the carbonate content had considerably 

 increased, so that the effect had been to change the original 

 condition of white alkali into one of black alkali. 



The danger of black alkali forming in calcareous soils 

 has recently been the subject of investigation in America, 



