19 



Satisfactory hclcls on tlie Carrington loam were comparatively 

 easy to locate, the re(.|uired number of pro])crly distributed forested 

 areas being easily found. 



On the Marsiiall silt loam, three of the five fields sampled were 

 forested. For the other two, the sets of samples were taken, in one case 

 alone: a line fence and in the other by the side of a roadway, neither of 

 which, within the recollection of old settlers in the neighborhood, had 

 ever been plowed. Land adjacent to the last two, however, had been 

 cleared of the forest for many years and given over to mixed farming 

 and hence it is probable that they also were originally in forest. These 

 two are designated as "cleared fields." 



In the case of each tyi>e an effort was made to locate the five fields 

 so that no two would be less than a mile apart and usually this was 

 found possible. On the Marshall silt loam three of the fields were a 

 little less than this distance a])art. 



Method of Sampling. 



Five fields ( Fig. 3) on each of the types chosen on the two drifts 

 were selected and from each one of these two sets of samples were 

 taken, the samples of each set being composites from ten borings 

 made approximatel}- 10 yards apart and to a depth of 3 feet. The sur- 

 face foot was taken in two 6-inch sections so that samples from 4 dif- 

 ferent depths were obtained, viz., 1-6, 7-12. 13-24 and 25-36 inches. 

 Two augers, one 2.0 and the other 1.5 inches in diameter, were used in 

 the work, the larger being employed to take the surface section and to 

 enlarge the hole preparatory to taking the lower sections with the 

 smaller. Care was taken to prevent the samples from the lower sec- 

 tions becoming contaminated with the soil from the upper part of the 

 hole as the auger was withdrawn. The composites of ten borings are 

 designated "Set 1 samples'' and "Set 2 samples." while the composites 

 made up in turn from these, and so representing twenty borings, are 

 referred to as the "field samples." The so-called "drift samples" for 

 each type were secured by combining equal weights of the "field sam- 

 ples,'' and so are composites from 100 borings scattered over a consid- 

 erable territorv. 



