EXPERIMENT STATION BULLETINS. 



075) 



TABLE 34.— RAINFALL AT EAST LANSING. 



CONCLUSION. 



The translocation of salts in the soil is due iiuiinly to water movements. 

 When large quantities of salt are present there is a movement to areas of 

 lower concentration even when water movements are prevented. Higher 

 water contents of the soil aid this movement. 



Since the soluble salt content of field soils is relatively low according 

 to the data presented, it is probable that plants are supplied with food 

 elements by diffusion from local areas around the roots only. 



The accumulation of soluble salts on the surface of uncropped areas 

 indicate that when water movements occur in the soil salts are carried 

 along with it. That these movements do not take place to any great 

 depth is evidenced by the results of various investigations showing but 

 little movement of water from the subsoil to the feeding zone of the 

 roots. It seems improbable that any great quantity of soluble material is 

 supplied to the plants from depths below those of root penetration. 



The quantity of soluble salts in greenhouse soils may become too great 

 for proper plant development. Moreover, plant growth may be inliibited 

 in muck soils by the accumulation of soluble substances in the upper 

 layers. 



The data presented show that plants may materially reduce the soluble 

 salt content of the soil. 



As a result of laboratory studies it appears that the constituents 

 of soil which have been cropped for a long period of years go into solution 

 at a somewhat slower rate than do tliose of the correspoilding virgin soils. 



