114 TEANSACTIONS OF THE ILLINOIS 



per cent. o£ water. Such soil (the ordinary prairie loam) may be 

 said to hold, in spite of thorough drainage, half its weight of water, 

 or enough to make a surface layer fifteen inches deep — three times 

 the amount required by vegetation during the summer! 



The practical question is, therefore: Can anything be done 

 towards husbanding this supply? It has already been pointed out 

 that naked, uncultivated soil loses by evaporation vastly more water 

 to the hungry summer air than is exhaled by the foliage of trees 

 and crops. In Mr. Hunt's tests, twenty eight non-selected samples 

 from cultivated land (mostly corn) gave an average of 12 per cent., 

 while the same number from uncultivated land (mostly stubble and 

 pasture) gave 10.3 per cent. It is instructive to note that in the 

 second foot in these cases, the difference in favor of the cultivated 

 soil is even more pronounced — 15 and 12.8 respectively. That is, 

 the cultivation of the surface causes the deeper layers — below the 

 plow — to retain more moisture. This is easily explained, but we 

 defer the matter for the present. 



But these differences came from soil as ordinarily left in com- 

 mon farming. Will more thorough pulverization of the surface 

 have proportionally better results? A remarkable case is given in 

 the series of tests, from the orchard of Mr. Hammond, compared 

 with specimens taken from an adjoining meadow with same soil and 

 altitude. The specimens were taken only fifteen rods apart. The 

 meadow had been mowed a month before; the orchard for two suc- 

 cessive years had been seeded with rye, which was plowed uuder each 

 year about the first of June. Subsequently this last season the land 

 had been once plowed and afterward harrowed several times, keep- 

 ing the surface in an exceedingly fine state of tilth. The orchard 

 soil proved to have 24.6, while that of the meadow had 12.1 percent, 

 of water! This is a most remarkable and instructive result. Can 

 we sufficiently appreciate the importance of surface tilth to make us 

 increase our energy in the practical affairs of the orchards and fields? 

 The proportion, 24 to 12, does not tell the whole story. We have 

 seen that crops suffer much when there is an an average of 13 per 

 cent, of moisture in the soil. Neither orchard trees nor ordinary 

 field crops can take all the water from any soil. We may say that 

 at least 10 per cent, will be thus beyond the reach of the roots' ab- 

 sorptive powers. Taking this amount from both samples, we have 

 14 and 2 as the proportional available water in the two cases. 



We should not leave this most instructive matter without quot- 

 ing further from the tests made in Hancock county. A potato field 

 and a wheat stubble was compared, and yielded 8 and 9 per cent, of 

 water — both very low! Evidently the peculiarity is in the potato 

 patch, not in the stubble. Now this soil had not been stirred since 

 the potatoes were dug, about the first of June- It had been deeply 

 turned up and left rough — just in condition for thorough evapora- 

 tion. 



