44 EXPERIMENT STATION. [Jan. 



the water soluble salines present. The soluble matter in the 

 three normal soils was very much less than in the soils which 

 had given trouble, although the normal soils had been used for 

 the continuous growing of tobacco for as long a term of years, 

 and had been as liberally fertilized, as the soils giving poor 

 results. 



It is impossible to say just how large an accumulation of 

 soluble constituents may take place before the plants will be 

 injuriously affected. The data at hand, however, would indi- 

 cate that a relatively wide latitude may be allowed on at least 

 some of the constituents. It is believed that the combined 

 effect of the total soJiihle mineral constituents in the soil is 

 responsible for the injurious effect on the growing plants 

 rather than an accumulation of any one of the soluble ele- 

 ments. It is probable, also, that the rainfall has an important 

 influence in this connection, plenty of rain having a tendency 

 to keep the soluble matter well below the surface, while the 

 absence of a normal rainfall would tend to draw the soluble 

 salts to the surface. 



It will be seen from Table 8, giving the average composi- 

 tion of the two types of soil, that nearly twice the amount of 

 solulde salines was found in the abnormal solids as was present 

 in the normal ones. A tobacco soil examined but not re- 

 ported here has shown as high as .18 per cent, water soluble 

 salines (equivalent to 5,448 pounds per acre), ai-id yet has 

 produced a fair crop of tobacco. On the other hand, serious 

 injury to the crop has been noted on soil which tested only 

 .14 per cent, soluble salines (equivalent to 4,152 pounds per 

 acre). Another fact should not be lost sight of, namely, that 

 the abnormal soils in all cases were underlaid with an imper- 

 vious or hardpan subsoil which prevented the free circulation 

 of the soil water. It seems probable, therefore, that the trouble 

 is due to, or is most likely to occur on, soils underlaid with 

 hardpan and in the absence of a normal rainfall, the accumu- 

 lated soluble saline matter being brought to the surface. 



The investigation brings out one fact of unusual interest, 

 namely, the large amount of water soluble potash as compared 

 with the total potash content of the abnormal soil. The 



