66 Elementary Principles of Agriculture 



99. Absorptive Power of Soils. Soils have the power 

 of absorbing many substances, particularly some that 

 are valuable plant foods. Prepare two lamp chimneys as 

 described in ]j 95b ; and fill with good field or garden soil. 

 Into one pour several ounces of water made deep blue 

 with laundry blueing. Note the color of the water when it 

 comes through the cloth below. Into the second chimney 

 pour foul water made by leaching compost. Coloring 

 matters or soluble salts like fertilizers, absorbed in this 

 way (physical absorption), are merely held more firmly 

 to the surface of the soil particles, so that they are not 

 readily leached out by percolating waters. Mineral 

 plant foods held in the soil in this way are available 

 for absorption by the roots of plants. 



Wood ashes contain the salts left from the plant 

 when the air-derived substances have been driven off 

 by burning. It represents the valuable salts absorbed 

 from the soil. Take some home-made lye and taste a 

 drop on the end of a broom straw. Allow to filter through 

 the soil as above and try the taste of the drippings. 

 Has the soil absorbed any of the salts? 



QUESTIONS 







1. What are the ends to be worked for in soil management? 

 2. What is meant by "soil?" How does a geologist classify soils? 

 4. What is the farmer's classification of the layers of soils? 5. Name 

 the four chief components of soils. 6. What are the advantages 

 and disadvantages of a sandy soil? 7. Of a clay soil? 8. Of a limy 

 soil? 9. Of humus in soils? 10. What is the importance of the size 

 of soil particles? 11. What do you understand by soil particles, and 

 soil granules? 12. What does the farmer mean by heavy and light 

 soils? ,13. What kind of soil warms up most quickly? 14. Why does 

 the farmer harrow or plow up 'the crust formed by rains? 15. What 

 is meant by dry-land farming? What is its advantage? Explain. 



