1912.] PUBLIC DOCUMENT — No. 31. 45 



average total acid soluble potash present in the three abnormal 

 soils was .1-11) per cent., of which .020.") per cent, (or nearly 14 

 per cent, of the total amount) was present in water soluble 

 form. The writer is aware that these facts are not in accord- 

 ance with the usual teachings, it being generally held that 

 potash does not remain in solution for any great length of time, 

 but is soon fixed as basic compounds in the soil, only to be 

 liberated gradually by chemical action. It does not seem im- 

 j)robable that the concentration of the soluble salines may in 

 a measure be responsible for the large proportion of soluble 

 potash present, and possibly even tends to dissolve greater 

 quantities of the fixed potash. The proportion of water solu- 

 ble potash in the normal tobacco soils bears out this theory, 

 as out of a total of .1731 per cent., only .0122 per cent, (about 

 7 per cent, of the total amount) was present in water soluble 

 form. 



The results in Table 8 are of interest in connection with the 

 question of the proper concentration of soil solutions most favor- 

 able to plant development. ISTumerous investigators have dem- 

 onstrated that one part of mineral matter in 1,000 parts of 

 water furnishes the best conditions.^ The average analysis 

 of the five normal soils shows the presence of 1.04 parts per 

 1,000, whereas in the abnormal soils nearly twice this amount 

 was present. It is well known that some plants stand a greater 

 concentration of soil solutions than others ; for instance, corn 

 and grass showed a wonderful development on soils wdiich were 

 so unfavorable for tobacco. Onions, on the other hand, seem 

 to be quite as susceptible to injury as is tobacco. The same 

 difference has been noticed in connection with the accumulation 

 of soluble mineral constituents in greenhouse soils. Soil solu- 

 tions too concentrated for cucumbers seem to he quite favor- 

 able for tomatoes. Little data is available in connection with 

 this whole subject of the concentration of soil solutions, and 

 further study with different plants is needed before any sweep- 

 ing conclusions can be drawn. It is not improbable that if the 

 amounts of the various soluble constituents in the soil are 

 present in certain proportions the plant may be able to with- 



1 Pfeffer, Vol. 1, p. 420; Stockbridge, Rocks and Soil?, p. 206. 



