42 



CHEMICAL COMPOSITION OF THE SOIL 



Below is a diagram showing roughly the distributions of elements 

 in the earth's crust. Of the last 4 %, 1.3 % is magnesium, 1 % is 

 sodium, 1 % is potassium, and all the remaining elements do not 

 quite equal 1 % of the earth's crust. 



OXYGEN 

 50 



QUESTIONS AND EXERCISES 



1. Name the two great classes of elements that enter into the soil. 



2. Name the metallic elements. 



3. Describe (a) aluminum, (6) calcium. 



4. Discuss (a) magnesium, (6) potassium. 



5. Describe (a) sodium, (6) iron, (c) manganese. 



6. Name some of the non-metallic elements of the soil. 



7. Discuss (a) oxygen, (6) silicon, (c) carbon. 



8. Describe (a) sulphur, (6) hydrogen, (c) chlorine. 



9. Discuss (a) phosphorus, (6) nitrogen. 

 10. Describe (a) fluorine, (6) boron. 



REFERENCES 



Chemistry of the Farm, Warrington. 



First Principles of Soil Fertility, Vivian. 



Soil Physics Laboratory Guide, Stevenson and Schwab. 



