MOVEMENTS OF SALTS IN SOILS. 



65 



In this table it will be observed that each and every ingredi- 

 ent has been recovered from the soil in larger amounts than 

 were recovered from the soil at the start and tjhe mean differ- 

 ences are recorded in the last line of the table, where, it will be 

 seen, that the excess amounts recovered range from 1.74 parts 

 of HPO 4 per million of dry soil in a column one foot in depth 

 to 41.29 parts per million of nitric acid (NO 3 ). A portion of 

 this increase is due to sails, which were carried in 1300 c. c. of 

 tap water, added to each cylinder to secure capillary movement 

 and whose composition is given below. The water added was 

 about one-fifth the dry weight of the soil. 



Amounts of salts in water added to the soil. 



In the surface two inches of soil there has been an extremely 

 large accumulation of nitrates, sulphates and chlorides ; so, too, 

 has there been an increase of the other three ingredients deter- 

 mined and, in every probability, considerable amounts of one 

 or more of the bases which are essential plant foods. So large 

 was this capillary concentration of the most soluble salts that 

 only 30.8 per cent, of the total nitrates, in the foot of soil, 

 remained below the surface two inches; only 20.6 per cent, of 

 the chlorides and only 25.3 per cent, of the sulphates; and yet, 

 to be serviceable to a crop, it should all remain below the sur- 

 face 2 inches. The amount of water which passed by capillarity 

 through the bottom layer of these 12 inches of soil was about 

 4. 37 inches inj depth. 



It must be said that the data given in the table, p. 64, do not 

 represent the maximum concentration which occurred in the 

 surface 2 inches. It was the cylinders examined on the fourth 

 or fifth dates which showed the largest accumulation of salts 

 in the surface two inches. Later, the capillary rise had become 

 so slow, on account of the drying out of the soils, that the back- 

 ward diffusion of the very soluble sa^ts, in several cases, espe- 

 5 



