SOILS, ETC. 131 



knowledge of the fact that all varieties of our indigenous 

 forest trees will grow thriftily upon all varieties of our soil; 

 even those whose most congenial habitat is upon the alluvial 

 soil of our river valleys, or upon the rugged slopes of the 

 valley -sides. 



This fact is now well understood by every farmer in the 

 State, and they also know that it requires positive exertion 

 on their part to prevent the natural encroachment of forest 

 growth upon their prairie farms as soon as the bordering 

 wood-land is protected from the annual prairie fires. This 

 encroachment of forest growth is equally marked upon the 

 alluvial or bottom prairies, the ordinary drift prairies, and 

 those in western Iowa whose soil is composed entirely of that 

 fine silt-like material before described under the head of Bluff 

 Deposit. 



The rapidity with which all kinds of our forest trees will 

 grow upon all varieties of our soil is quite astonishing, for 

 the superiority of these soils is as strikingly shown in the 

 growth of trees as it is in the production of the staple crops 

 of corn and wheat. So rapid indeed is the growth of trees, 

 both by natural and artificial propagation, that not only 

 is there a gradually increasing area occupied by them, but 

 there seems to be sufficient evidence that there is more wood- 

 fuel now existing in Iowa than there was at the time of its 

 first settlement, notwithstanding the constant consumption of 

 it by the inhabitants since then. 



In many parts of the State the supplies of fuel are derived 

 almost exclusively from trees that have grown from the seed 

 since its settlement. Not only has the new growth reached 

 a size that will answer for fuel, but hundreds of farms 

 have been re-fenced with rails that grew in adjoining wood- 

 land since they were first cultivated. 



These facts are certainly sufficient to show that there is 

 no unfitness of any of the soil of Iowa for the growth of 

 its forest trees, and their original healthful growth, in all 

 parts of the State, even in the smallest numbers, is sufficient 

 evidence that their absence upon the remainder of the surface 



