8 MASS. EXPERIMENT STATION BULLETIN 324 



The soils represented by these samples show wide variations in texture when 

 the}' are separated into the different grades of soil grains. High potash in the 

 whole soil accompanies the larger proportions of clay, whether it be surface soil 

 or the lowest levels. All of these soils were deposited from water coming from the 

 melting glaciers. Excavations reveal very irregular distribution of clay, sand, 

 and gravel; but the deposits represent long periods of alternate summers and 

 winters, with the accompanying thawing and freezing, floods, and ice. The 

 extremes in texture and potash are shown by the Campus Trench near Draper 

 Hall and the Forage Crop Plots, yet they are less than 30 rods apart and practically 

 in the same field. 



The loss in weight which occurs when a dry soil is heated to red heat is com- 

 monly calculated to be organic matter; but this is not accurate because the clay 

 does not part with all its water in the drying oven but does lose it at the higher 

 heat. Lime carbonate also loses weight on heating to redness and is changed to 

 quicklime. Frost's results on the soils in this investigation are of interest because 

 in all cases except clay and limestone soils the loss at red heat was less than 1 

 percent in the samples from the 3rd and 4th foot, while in the surface soil it ran 

 as high as 12 percent. Such results agree with those reported for organic carbon 

 at the Wachusett Reservoir and confirm Latimer's statement about the depth 

 of weathering of glacial drift from which the soils are formed. 



During the existence of the experiment station many samples of soil have been 

 analyzed, which have been sent from all parts of the State. In the Annual Report 

 of January 1911 there were published detailed results on 148 samples. From these 

 pages it was found that the potash dissolved in strong acid fell below .25 percent 

 in 88 samples; was between .25 and .45 percent in 39 samples; and amounted to 

 .45 percent and upward to 1.02 percent in 21 samples. Little can be learned from 

 these results beyond the. facts that many of the low results were from sandy and 

 sandy loam soils, while several of the highest results were obtained from garden 

 soils. Hilgard, in his book "Soils," makes the statement from long experience 

 that soils with less than .25 percent of acid-soluble potash will need potash fertiliz- 

 ers, while those with .45 percent or more seldom show any benefit from such 

 fertilizer. One fourth of the samples were between these two extreme groups and 

 should require some thoughtful observation of results of fertilizers. 



At the International Congress of Soil Science at Washington, D. C, in 1927, 

 the consensus of opinion held the strong hydrochloric acid solution of soils to be 

 an excellent index of the extent to which the soil minerals had been changed by 

 weathering. The relation of the soil minerals to the underlying drift and rocks 

 is better shown, however, by determining the total percentages by other methods 

 such as fusion with some chemical. 



In the soil surveys of Massachusetts only two chemical analyses of typical soils 

 have been reported. These soils were Gloucester stony fine sandy loam and 

 Becket loam, the complete analyses of which were published in the Soil Survey 

 of Franklin County (p. 35). Both of these soils are derived from granite, gneiss, 

 and related rocks. The deep subsoil of Becket series is compact and fine, while 

 Gloucester soils are underlaid by looser and coarser material. In these analyses 

 the soils were not dissolved in acid but changed to soluble compounds by fusion 

 with alkalies in order to recover all the plant food. The data for total potash are 

 given here. 



