IIG TKANSACTIONS OF THE ILLINOIS 



great economy would result in supplying the water by means of tile 

 laid just below the plow. This has been practiced in the flower-beds 

 at the State University for some years, and found very satisfactory. 



Turning now to another series of comparisons, we see from Mr. 

 Hunt's tests, something of the effect of tile drainage upon the soil 

 during drouth. Forty samples gave an average for tiled of 14.1, 

 and 13.2 per cent, of water for untiled soil. Bat the fairest tests 

 wei'e in oat stubble in one case, and broom-corn field in another. 

 The first gave 14.2 and 13.4 respectively, for the tiled and the 

 untiled land ; the second 10.4 and 14.7 per cent, in same order. In 

 these cases there was no other perceptible difference in the plats 

 tried than that caused by the drajns. The land was the same in 

 quality and exposure ; the same in altitude and surface drainage ; 

 but there was a uniform difference in favor of the tiled soil. This 

 was upon level prairie land. As the quality of the soil has much to 

 do with the retention of water, it is probable that upon clayey soil, 

 inclined to " bake," the effect of tiling would be still more pro- 

 nounced in its favor. Surely there is no just cause for alarm in the 

 use of tile to carry off the surplus and injurious water of springtime 

 and wet seasons, on account of ill effects during drouth. 



Let us now endeavor to understand the reasons underlying the 

 foregoing results of tillage and drainage. It is quite commonly 

 asserted that one of the advantages of tile drains is that they pro- 

 mote the condensation of moisture from the air during drouth. The 

 opinion probably grew out of some one's thinking, rather than from 

 actual experiment ; for there are no facts recorded, so far as 1 am 

 able to ascertain, to sustain it, while there is much to disprove it. 

 It is in the same way supposed that thoroughly pulverized soil gains 

 water by absorption, especially during dewy nights. Investigations 

 carried on at the Houghton experimental farm in New York, those 

 of Professor Sanborn in Missouri, and others, show that soil ordina- 

 arily loses water at night as well as during the day. Dew itself con- 

 sists in good part of water escaped from the soil during the night, 

 and condensed upon the colder herbage. Road-dust sometimes 

 shows by its color that it is somewhat damp in the morning ; but 

 the water comes from the deeper parts of the earth, not from the 

 air. It gains moisture at night simply because evaporation is not so 

 great then as in the daytime. 



The idea of dew absorption by soil ought to be recognized as 

 hypothetical when we remember that the temperature of the earth 

 during a summer night is always higher than that of the air above 

 it. A warmer body cannot condense water from colder air. As a 

 general statement we may say that soil constantly loses water and 

 never gains it by absorption from the air during rainless weather. 



Again, it is thoroughly demonstrated that plants do not absorb 

 water from the air by their leaves. They too constantly exhale 

 the moisture of the soil gathered by the roots. If wilted plants 



