114 Irrigation and Drainage 



Total water retained.... I 8 ' W \ * 2 ' 4 3 ' 51 *' 4 ' 576 ' 2 5 < 831 S 

 I per cent 4.24 5.05 7.25 9.41 11.82 



Water retained after 4/gms. 3,128. 3,551.1 4,259.9 5,672. 6,659.7 



days .................. I per cent 6.25 7.238 8.785 11.66 13.5 



Water retained after 9/gms. 2,926. 3,213.5 4,094.7 5,416.2 6,452.8 

 days ................... I per cent 5.846 6.753 8.445 11.13 13.08 



fgms. 10,425.2 10,356.2 10,329.1 10,289.7 10,606.8 



'Ipercent 20.84 21.12 21.3 21.15 21.5 



Total weight of dry sand... gms. 50,050. 49,060. 48,490. 48,650. 49,340. 



A glance at this table shows how completely and how rapidly 

 water will drain away by downward percolation from the coarse 

 and fine sands when there is nothing within 8 feet of the surface 

 to prevent it. It will be seen that in four days the coarsest sand 

 had lost nearly three-quarters of all the water it could contain 

 under flooded conditions, while the finest had lost nearly one- 

 half ; and this has occurred, too, under such conditions that 

 standing water is maintained within 8 feet of the surface. Had 

 standing water been 16 feet from the surface, it is quite likely 

 that the surface 8 feet of these sands would not have retained 3 

 per cent in the coarsest sample nor 5 per cent in the finest. 



With such a rate of loss of water from sands as this, it must 

 be plain that the coarser soils, when they are long distances from 

 standing water in the ground, or are not underlaid with a more 

 impervious stratum near the surface, must lose the water which 

 falls upon them as rain so rapidly that even in very humid regions 

 they cannot maintain profitable crops without irrigation. 



It is this fact of coarse texture, coupled with the long inter- 

 vals of deficient rain, more than a lack of plant-food, which has 

 maintained in an unproductive state the extensive areas of sandy 

 lands found in Minnesota, Wisconsin, Michigan, New York, New 

 Jersey, and further south, in the United states, and throughout 

 Belgium, Holland, and the plains of northern Germany, in 

 Europe. Had the soils of these areas identically the same 

 chemical composition, but a texture as fine as that of our best 

 soils, so that water would drain from them no more rapidly, 

 profitable agriculture could be practiced upon them under the 

 rainfall conditions which exist. And it is possible to so supple- 



