POTASH IN MASSACHUSETTS SOILS 11 



Excavations have shown that the two fields probably possess distinctly different 

 underlying drift. The Forage Plots included in Frost's work are immediately 

 adjacent to the North Soil Test and were positively coarser in their lower levels. 

 On the other hand, a deep trench recently dug across the end of the original Field 

 G showed heavy clay in those levels. Field G contained more potash in fine 

 particles to be acted on by water, and also an underlying unweathered drift of 

 great capacity to retain water. Hence a liberal supply of soil-potash was available. 



Potash in Sand, Silt and Clay of Different Soil Series 



Samples of soil representing different soil series have been analyzed with the 

 object of comparing the percentages of total potash in the two groups of soil 

 particles, sands and silt-clay. Some of the samples were from series of wide dis- 

 tribution. Others were from series with distinctive rocks predominating in the 

 drift from which the soils were weathered. The samples were taken at locations 

 which appeared to be distinctive of the particular series, shown by rock frag- 

 ments, color of soil, and other characteristics. They were essentially random 

 samples of Massachusetts soils, because there are numerous variables influencing 

 the chemical composition of any particular soil series. 



Glacial action has been stated by Latimer as reducing rocks to sand and rock 

 flour. The softer minerals like feldspar would be more finely ground than the 

 harder quartz. Therefore, the rock flour might contain more feldspar and the sand 

 more quartz. Mica, which splits into thin, paper-like sheets, would slip and 

 slide and instead of being pulverized to flour might remain as fine scales in the 

 sands. Mica crystals contain 9 percent of potash, while potash feldspar contains 

 16 percent. Rock flour has been subjected to the dissolving effect of water through- 

 out its formation and subsequent weathering, which must modify the percentage 

 of potash originally present in the feldspar much more than the percentage of 

 that element in the mica scales. 



Among the different soils in the table, Brookfield, Cheshire, Dover, Gloucester, 

 and Merrimac soils have been mentioned as influenced respectively by schist, 

 sandstone, limestone, and granite in the glacial drift from which they have been 

 weathered. The Gloucester and Merrimac soils are both granitic but differ in 

 the form of the drift: the Gloucester drift was deposited directly from the ice 

 as it melted, while the Merrimac drift was washed away in the streams of water 

 from the melting ice and deposited at some distance. Becket soils were weathered 

 from drift containing more gneiss than granite, which produced a finer grained, 

 more compact drift than that underlying Gloucester soils. Becket soils are com- 

 mon on the hills west of the Connecticut River. Charlton soils form an important 

 series in Worcester County and were weathered from drift containing both schist 

 and granite, which is compact and retentive of moisture. Holyoke soils are 

 limited to the vicinity of the Holyoke Mountain Range, and are of interest 

 because the distinctive rock which characterizes them is trap rock or diabase, 

 and diabase contains little if any potash. Lenox soils are underlaid by drift in 

 which limestone and schist are mingled together. The sample was taken in the 

 vicinity of a mica schist outcrop and its coarse sand contained numerous grains 

 of limestone, which were identified by the action of weak acid on them. 



Three samples of soils were taken near outcrops of ledges where the soil was 

 not more than a foot in depth above the underlying rock. It is uncertain how 

 much of the soil was weathered from the rock and how much from thin glacial 

 drift. Diorite rocks are not mentioned by Latimer in connection with any series 

 of soils. They are mentioned by Emerson in "Geology of Massachusetts" as 



