INSTITUTE, PUSA, FOR 1917-18 27 



carbon dioxide, (d) a somewhat indefinite phase consisting 

 of saturated solutions of calcium citrate with increasing 

 concentrations of calcium bicarbonate, and (e) a final phase 

 of a saturated solution of calcium citrate and calcium 

 bicarbonate. Extractions of the soil in the absence of 

 calcium carbonate with solutions approximating in com- 

 position to the phases denned above yielded values commen- 

 surate with those obtained from the corresponding mixture 

 of carbonate of lime and soil. Consequently the applica- 

 tion of Dyer's method to calcareous soils is in effect an 

 extraction with a series of .dissimilar solutions the com- 

 position of which mainly depends upon the calcium 

 carbonate content, and this being the case, the values 

 obtained in the case of calcareous soils of varying lime 

 content can bear no very definite relationship one with the 

 other and much less with non-calcareous soils. In the case 

 of non-calcareous soils the value of Dyer's method is entirely 

 due to a rigorous correlation of the analytical data with 

 the known manurial reaction of specific soils, but such 

 rigorous correlation is almost entirely lacking in regard to 

 highly calcareous soils. The interpretation to be placed 

 on the values obtained is very indefinite, and so long as this 

 condition obtains the method must remain of dubious value. 

 Incidentally during the course of this investigation, it 

 was discovered that the presence of calcium carbonate 

 seriously interfered with the estimation of citrate-soluble 

 phosphoric acid by the standard method under standard 

 conditions. This is caused by the phosphate present 

 in the ammonium citrate solution reacting with the calcium 

 carbonate to produce insoluble calcium phosphate. 



VI. Soils and Soil Conditions. 



(a) Paddy Soils. The study of the relationship of the 

 gaseous products of decomposition to these soils has been 

 continued, and particularly that of carbon dioxide and 

 hydrogen. It has been shown that carbon dioxide when 

 present alone can persist as such, but that in admixture 

 with hydrogen, and under biological influences, a recom- 



