40 KANSAS ACADEMY OF SCIENCE. 



come before experiments determine what system of cultivation and variety 

 of crops are best adapted to the wants of that particular section of the State. 



In passing over the State from east to west, we find that a gradual change 

 in the soil takes place — that of eastern Kansas being as distinct from the 

 soil of the western counties, as is found in the climate of these respective 

 localities ; while in central Kansas we find the soil to be a compromise be- 

 tween the two extremes. 



The soil of eastern Kansas is a black loam, resting on a clay formation; 

 that of central Kansas a dark, sandy loam, resting on a porous marl clay 

 formation ; while that of western Kansas has a still more sandy surface soil 

 and more porous subsoil. This is the general subdivision, subject to occa- 

 sional variations. As a rule, the surface soil grows deeper and the subsoil 

 more porous, as we pass from the east towards the west. 



The rainfall is graduated from east to west across the State, with as much 

 regularity as the soil, the precipitation being about one-third greater in east- 

 ern Kansas than in western, and about one-fifth greater than in central Kan- 

 sas. But here a law of compensation enters in to modify this difference, the 

 moisture-absorbing and retaining qualities of the soil being much greater in 

 central and western Kansas than that of the eastern portion of the State. 

 As an illustration of this point, let us take a tract of cultivated land with a 

 black-loam surface soil one foot deep, resting on a clayey subsoil. On this 

 tract of land two inches of rain falls. One-half is sufficient to thoroughly 

 saturate the surface soil down to the clay ; the balance is rejected for want 

 of capacity in the soil to store it, and in consequene this surplus flows off' 

 into the stream. 



Let us now take another tract of sandy loam, two feet deep, resting on a 

 porous subsoil, on which two inches of rain falls. This soil, having double 

 the storing capacity of the tract first named, receives all the rain, and in- 

 stead of wasting half, stores the full amount for future use. 



The natural deduction from this would be, that the soil two feet deep, 

 storing a double quantity of moisture, will be more than twice as long in 

 parting with it; not only because it holds more of it, but because it is stored 

 further from the surface and from the influences of the sun's heat, drying 

 winds, and consequent evaporation. 



The experience of Eastern farmers who have carefully noted the effects of 

 drainage on their soil is, that a tract of land on which the surface soil has 

 been deepened by drainage will produce crops on one-half the rainfall that 

 was necessary prior to drainage ; or in other words, by doubling the capacity 

 of the reservoir for storing and retaining the moisture in the soil, a much 

 less quantity of rainfall is now necessary to produce like results. 



It would seem to follow from this, that the amount of rainfall sufficient to 

 raise crops in one locality may be either too much or too little for some other 

 localities having a more or less absorptive soil. 



For instance, if thirty-five inches be the amount of annual rainfall neces- 



