32 FARM AND SCHOOL PROBLEMS. 



21. How should the outlet of a drainage system be protected? 



22. Why is sand very soft and yielding under water and why is 

 it immediately hard after the water is withdrawn? (Observe results on 

 the beach or shore of a body of water). 



23. Why is sand soft and yielding when dry and why is clay that 

 has lost in moisture very hard and firm? 



24. How do growing crops help the tile drains to dry the soil? 



25. How do growing crops expand the growing surface of the soil? 



26. What is the relation of tillage to tilage? 



27. What is Dry Farming? 



28. What is a reservoir? Describe different uses. 



29. What .becomes of the rain that falls on the farm? 



30. In what 3 forms does water exist in the soil? Which form is 

 most useful to plants? 



81. What is capillary water? Hygroscopic water? 



32. What kind of soil holds the most capillary moisture? The 

 least? 



33. What effect on conservation of moisture does rolling have on 

 loose soils? 



34. What is a dust mulch? Its effect? How made? 



35. W'hat should distance between tile drains depend upon? 



36. How do you determine the depth at which soil should be 

 drained? 



37. What is stagnant water, and the cause of alkali lands? 



38. Why should the fall for a tile drain be uniform and if pos- 

 sible not less than 2 inches per 100 feet? 



39. Explain how irrigation, surface culture and drainage may effect 

 the climate of a region. 



40. How does drainage effect vegetation, as to forestry? as to field 

 crops? as to weeds? 



41. Will all the water run out of a level drain? 



Reference for Collateral Reading. 

 BOOKS. 



1. Irrigation & Drainae King*, 8-12 Macmillan Co., $1.50. 



2. Irrigation Institutions Mead, 8-12 Macmillan Co., $1.25. 



3. The Conquest of Arid America Smythe, 8-12 Macmillan Co., $1..V\ 



4. Practical Farm Drainage Elliott, 8-12 John Wiley and Sons, $1.50. 



5. Physics of Agriculture King, 8-12 F. H. King, Madison, Wis., $1.50. 



6. Farm Drainage French. 



7. Drainage for Profit Waring. 



*F;^ures 8-12 indicate grades to which book is adapted. 



