Loess Soils of the Transition Region 



33 



colorimetrically the Hilgard solutions ran much higher than did 

 the Rather sohitions, this probably being due to the fact that the 

 small amount of extremely fine clay which is carried through the 

 filter in the Hilgard method renders the solution less transparent 

 in the colorimeter. The following table is self-explanatory. 



Table XIX. Comparison of the Results of Different Methods of 

 Extracting Humus 



CONCLUSIONS 



1. The Rather method for the determination of humus is the 

 most practical of all gravimetric methods tried, and seems to be 

 the most accurate method for determining humus in the first and 

 second feet of Nebraska loess soils. 



2. Below the first and second feet, the colorimetric method is 

 the most practical method. 



3. For the determination of humus-nitrogen, the Alway-Bishop 

 method seems to be the most satisfactory method as it combines 

 accuracy with economy of time. 



4. The humus content of the first two feet of the eastern loess 

 soils in Nebraska is approximately twice that of the first two 

 feet of the western loess soils. 



5. On the other hand, the humus content of the fifth and sixth 

 feet of the western soils is two or three times that of the eastern 

 loess soils of the same depth. 



6. The decrease of humus content with ^the depth of soil is 

 therefore much more gradual in the case of the western loess 

 soils than it is in the case of the eastern soils. 



7. The humus-nitrogen ratio is slightly higher in the east than 



143 



