EXPERIMENT STATION BULLETINS. 



599 



TABLE 12.-QUANTITIES OF FIXED CARBON DIOXIDE IN SOIL EXTRACTS IN P.ARTS PER MILLION ON 



SOILS. 



As might be expected, hydrated lime and CaCOg greatly increased 

 the quantities of fixed CO2 in the extracts. The other treatments show 

 a general tendency towards reducing this compound in the first leach- 

 ings but greatly increasing it in the second leachings. This remarkable 

 situation leads to the conclusion that some of the basic elements added 

 in the treatments may occur in the second extract as carbonates. 



Quantities in parts per million in soils of NO3 found in the extracts 

 from first leachings after the NaNOg treatment are: No. 1, 557.8; No. 

 2, 516.2; No. 3, 578.4; No. 4, 585.5. Second leachings from this treat- 

 ment gave only a trace of NO3 in the extracts. 



Residuary Effects. 



The residuary effects of the several treatments as represented by 

 analyses of the second leachings vary so much with each treatment and 

 appear to have such a marked bearing on soil fertility and management 

 that a full discussion of points not already given is thought best. It 

 is not supposed that these effects would be produced in similar soils 

 under field conditions, however, in certain respects they point to what 

 might be expected particularly in soils subjected to considerable leaching. 



K fixed in the soil from KCl gradually becomes soluble so that a 

 soil treated with this fertilizer probably gives much more K to its solu- 

 tion for several years after treatment than it did previous to the treat- 

 ment, but the acid soils did not give up K to the same extent as the 

 alkaline soils. The CI, however, will be reduced in quantity below that 

 required to combine with the K as KCl. The KCl treatment then tends 

 to leave the soil solution higher in content of K, CI, P, Na, Fixed COj, 

 SO3, and Al, but lower in SiO,, Ca, Mg, and Fe; and most of the K is 

 in combinations other than KCl. 



More soluble P was found in the acid soils than in the alkaline soils 

 as a residuary effect of the KCl treatment. The general effect of the 

 K and Na salts was to decrease the quantities of Ca in the second ex- 

 tracts below those of the checks. How soon this condition would be 

 brought about by soil leaching would probably depend upon the quan- 

 tities and combinations of the several elements in the soils. For instance, 

 providing a soil is high in Ca content, as is soil No. 1, more KCl and 

 a longer time would be required to reduce the Ca content below that 

 of a check. This action is also apparent in the case of some other treat- 

 ments. 



