102 SOILS: PB0PJSRTIE8 AND MANAGEMENT 



silts, and clays than the representatives of the other 

 soil provinces; this is true also of the glacial soils, but 

 to a less degree. Under such conditions of weathering 

 the sands have not as yet been depleted of their stores 

 of essential elements. Average data compiled from a 

 number of soil analyses by Hall/ presented below, tend 

 to corroborate the data already noted and that obtained 

 by Loughridge ^ of California : — 



Composition of Sou. Separates 





'SiOz 



AI2O3 



FeaOa 



CaO 



.4 



MgO 



K2O 



P2O5 



Coarse sand (1-.2 mm.) . 



93.9 



1.6 



1.2 



.5 



.8 



.05 



Pine sand (.2--.04 mm,) 



94.0 



2.0 



1.2 



.5 



.1 



1.5 



.1 



Silt (.04-.01 mm.) . . . 



89.4 



5.1 



1.5 



.8 



.3 



2.3 



.1 



Fine silt (.01~.002 mm.) . 



74.2 



13.2 



5.1 



1.6 



.3 



4.2 



.2 



Clay (Below .002 mm.) . 



53.2 



21.5 



13.2 



1.6 



1.0 



4.9 



.4 



76. Value of a mechanical analysis. — It is now evi- 

 dent that the proper interpretation of a mechanical 

 analysis throws considerable light on the probable physical 

 and chemical properties of a soil. To the trained ob- 

 server the preponderance of sand or clay signifies certain 

 physical properties which may affect the plant not only 

 mechanically, but physiologically as well, through varia- 



1 Hall, A. D., and Russell, E. J. Soil Surveys and Soil 

 Analyses. Jour. Agr. Science, Vol. IV, Part 2, p. 199. 1911. 

 Also a Report of the Agriculture and Soils 'of Kent, Surrey, and 

 Sussex. Board of Agriculture and Pislieries. 1911. 



2 Loughridge, R. H. On the Distribution of Soil Ingredi- 

 ents among Sediments Obtained in Silt Analyses. Amer. 

 Jour. Sei., Vol. VII, p. 17. 1874. 



In this connection see also Puehner, Dr. Uber die Ver- 

 tielung von Nahrstoffen in den Versehieden Feinen Bestandteilen 

 des Boden. Landw. Ver. Stat., Band 66, Seite 463-470. 1907. 



