31 

 B. LIME SUPPLY. 



1. Carbonates. 



The carbon dioxide in the field samples is reported in tables 21 to 

 23. Only one determination was made for each sample, but a check on 

 the accuracy of these is furnished by the determination of the amount 

 in the "drift samples," prepared by compositine: equal weights of the 

 five field samples. The full agreement of these may be seen from the 

 last two columns in the tables. 



Carrington Silt Loam. The amount of carbonates on the Kansan 

 is practically negligible and varies but little from field to field, the 

 average of the carbon dioxide in the three foot section of the different 

 fields falling between 0.051 and 0.062 per cent, with an average for all 

 fiveof 0.057 (Table 21). 



On the Late Wisconsin two of the fields, 1 and IV, show a similar 

 low content, but two, II and III, show an appreciable amount in the 

 second and third foot-sections, and the fifth, V, the third foot only. 

 The maximum, 3.14 per cent, is found in the third foot of Field III. 



It is evident that the carbonate on the Kansan has been leached 

 out to a depth greater than three feet and that the same is true in the 

 case of two of the fields on the Late Wisconsin, but in general the leach- 

 ing on the latter has not progressed nearly so far. 



Fargo Silt Loam. On this type (Table 22) the carbonate content 

 on the Kansan varies considerably from field to field, in two, I and IV, 

 there being no more than in the Carrington silt loam on the same drift, 

 while in the three others an appreciable amount was found in the third 

 foot-section. In all four sections in Field V the content is compara 

 tively high. 



