38 DRY FARMING 



determined by the texture of the soil. The soil must 

 furnish the mineral plant food elements and nitrogen. It 

 absorbs and retains the rainfall to be given up to the 

 plants as needed. It absorbs and transmits heat upon 

 which plant life is dependent. These factors we can in 

 a large measure control by our farm practices. In order 

 to know the best practices to pursue, it is essential that 

 we know why and how the soil responds to different 

 treatment. 



HISTORY AND PHYSICAL PROPERTIES. 



28. Origin. Geologists tell us that the earth was at 

 one time a molten mass cast off with its whirling motion 

 from the sun. Through many centuries this mass slowly 

 cooled, the molten materials forming a crust of solid rock 

 and the vapors condensing to water to form lakes and 

 oceans. The rock was broken down to a disintegrated 

 mass by the grinding action of the glaciers and the 

 slower process of weathering. Part of this disintegrated 

 material was carried away and redeposited by the wind 

 or water, becoming again cemented in stratified form 

 into rock. Part of it remained in place and formed the 

 beginning of the soil, accumulating slowly through the 

 ages by Nature's processes. 



The forces of disintegration and transportation have 

 been at work during all time. The power of freezing 

 and thawing in crumbling down rock is familiar to all. 

 The deep crevices in granite rock w r ith the pile of 

 crumbled-off material at the base tells the story of 

 Nature's work. The effects of water with its driving 

 force as rain, and its dissolving and wearing action in 

 flowing over rock surface are well evidenced in the 



