14 FARM AND SCHOOL PROBLEMS. 



4. Make an experiment by placing some soil of each variety in a 

 test tube, filled with water; shake well and allow the particles 

 to settle. Note results. Which kind of particles settle most 

 rapidly? 



Fertilizer Experiments By the School. 



1 . Study composition of soil humus or organic matter. Use soil 

 auger to determine color and formation of soils at different 



depths. Examine the three distinct layers the surface soil, the 

 subsurface soil and the subsoil. Examine the differences as 

 shown on the side of a deep ditch. 



2. Look along rock exposures or foundations of buildings for 

 evidences of crumbling rock. What causes this decay? What 

 term is given to the product of this decomposition? 



3. Examine the bank or sides of any freshly made excavation or 

 cut. How does the color of the material in the upper part of 

 the cut differ from that in the lower? Look for roots of trees 

 and other forms of vegetation. What work are they doing? 

 How do they aid in making soil? 



4. Examine the material just below the leaves in the woods or 

 the sod or plant refuse in the field. What is the color? De- 

 scribe the texture? What is its origin? 



5. Take samples of the soil from the upper slopes of a fairly steep 

 hill and from its base. Compare the two as to colo'r, texture 

 and composition. Which would be considered the richer soil? 

 What has caused the difference? 



6. Examine the soil of an old cultivated field and compare it with 

 the soil of a fence row or uncultivated field or new ground 

 that has never been plowed and note the difference. Why this 

 difference? 



Questions. 



1. What is the relation of geology to agriculture? 



2. What is soil? 



3. Discuss four ways by which soils are formed? 



4. How do plants and animals help to form soils? 



5. What are loamy soils? Sandy soils? Clay soils? 



6. What is a limestone soil? An alkali soil? 



7. How may subsoil differ from surface soil? 



8. When is a soil fertile and how may it become depleted of fer- 

 tility ? 



9. When is a soil poor? Barren? Arid? Arable? 



10. What is available plant food? 



11. Can a soil be rich in plant food elements and at the same time 

 be poor in available plant food? Why? 



