106 SOILS. 



impracticable. In actual practice it is frequently possible to 

 improve such soils by properly distributing upon them the 

 washings of the adjacent hills, which will always carry sands 

 of many grades; and when it is intended to improve garden 

 land by hauling sand it is important to choose the latter so as to 

 complement the deficient grain-sizes of the soil. The sand of 

 wind drifts or dunes is generally well adapted to such improve- 

 ment, being, as Udden x has shown, of a fairly definite com- 

 position of sufficiently wide range of grain-sizes for the pur- 

 pose. 



The effects of humus in modifying soil texture are discussed 

 farther on. 



1 The Mechanical Composition of Wind Deposits, Bull. No. i, Augustana Library 

 Publications; 1898. 



