THE ORGANIC MATTER OF THE SOIL 



119 



the percentage of nitrogen in the soil is multiplied by 20, a 

 rough idea of the amount of organic matter may be obtained 

 (N X 20 = organic matter). The following data from Rost 

 and Alway x illustrate not only the variations in organic 

 matter and nitrogen that may be expected in the surface and 

 subsurface of different soils, but the correlation between the 

 organic matter and nitrogen just mentioned: 



Table XXIV 



AVERAGE PERCENTAGE OF ORGANIC MATTER (C X 1.724) AND 



NITROGEN IN THIRTY REPRESENTATIVE MINNESOTA TILL SOILS 



FROM THREE SERIES. THE FIGURES FOR EACH OF THE 



THREE SOIL TYPES ARE AVERAGES OF TEN ANALYSES. 



The following tentative classification of mineral soils on the 

 basis of their percentages of organic matter and nitrogen is 

 offered for generalized field use : 



Table XXV 



Description 



Percentage of 

 Organic Matter 



Percentage op 

 Nitrogen 



Low 



Medium . 



High 



Very high 



.0— 3.0 



3.0— 6.0 



6.0—10.0 



above 10.0 



.00— .10 



.10— .25 



.25— .40 



above .40 



1 Eost, C. O., and Alway, F. J., Minnesota Glacial Soil Studies: I. A 

 Comparison of the Soils of the Late Wisconsin and the lowan Drifts; 

 Soil Sci., Vol. XI, No. 3, pp. 161-200, Mar., 1921. 



