26 



2. Texture of Fine-earth. 



As the most satisfactory method of ascertaining the similarit)' in 

 texture of the fine-earth of the samples used in this study the determi- 

 nation of the moisture equivalent (7) was selected. The relation of 

 this to the mechanical composition and other physical constants has 

 been discussed by various authors as mentioned above. 



The moisture ecjuivalents of the samples in the two sets from 

 each field were determined (Tables 15 to 18). The data in Table 15. 

 the first part of table 16 and those for Field T in the first part of table 

 17, are the means of duplicate determinations, the others being derived 

 from single determinations. The concordance of duplicate determina- 

 tions may be illustrated by the results from the 136 samples mentioned, 

 only two showing a difl:'erence greater than unity. Another illustration 

 is afforded by the data in table 19. 



Carrington Silt Loam. On the Kansan Drift this type showed 

 (Table 15) very little variation from set to set within the same field 

 and but a slightly greater one from field to field, the latter being the 

 most marked in the two sections from the surface foot where there was 

 also the greatest variation in the percentage of organic matter (6, p. 

 18). The highest value, ZZ.S, was found in the surface section, and 

 the lowest, 22.1, in the third foot. 



On the Late Wisconsin the variation from field to field was no 

 greater than on the Kansan, but in Field III the first set averaged only 

 20.5 and the second 26.7, compared with 34.8 for Set 2 from Field I. 

 The latter field differs markedly from the four others on this drift and 

 shows the highest value of all the fields sampled on this type, those for 

 the four sections ranging only from ZZ.Z to 2>?.?^: The averages for the 

 five fields on the two drifts are very similar. 



Fargo Silt Loam. (")n the Kansan (Table 16) this type shows little 

 variation either within the same field or from field to field, but on the 

 Late Wisconsin there is a somewhat wider variation in both. The 

 range is from 23.1, found in the subsoil to 52.5 in the surface. The 

 averages for the surface 6-inch sections on the two drifts show a 

 marked difference, that for the Kansan being 45.9 compared with 35.9 

 on the other. This, in all probability, is due to the larger amount of 

 organic material in the fonner (6, p. 18) as indicated by the per- 

 centages of organic carbon (Table 53), nitrogen (Table 57) and vola- 

 tile matter (Table 52). On the Kansan the organic carbon rises to 

 9.47 per cent compared w ith 5.71 on the Late W^isconsin. 



