EXERCISE 14 (Continued) 



5. Study the structure of the soil grains, that is, whether they consist of single particles or a 

 number of soil particles. If single, they will appear transparent under the microscope. The black or 

 dark particles unless covered with organic matter are compound. Compute the percentage of single 

 and of compound particles. 



Questions. Where are the most friable or crumbly soils located, — on the table land, slope, or bottom, 

 and why ? How does structure affect the' value of soils ? What are the principal factors determining the 

 structure of soils? 



References. Waters, H. J. Essentials of Agriculture, pp. 58-64. Ginn and Company. Burkett, C. W. 

 Soils, pp. 34-40. Orange Judd Company. King, F. H. Physics of Agriculture, pp. 51-53. Mrs. F. H. King. 

 Hilgard, E. W. Soils, pp. 83-107. The Ma cmillan Company. King, F. H. Physics of Agriculture, p. 51. 

 Merrill, G. P. Rocks, Rock Weathering, and Soils, p. 287. Hilgard. Soils, pp. 83-107. 



MICROSCOPIC EXAMINATION OF SOIL PARTICLES 



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