HOW BOILS LOSE NITROGEN * 109 



the water supply of soils affect the supply of nitrogen? 

 4. What three things are necessary for the formation of 

 nitrogen compounds in soils? 5. What becomes of the 

 dead leaves of trees? 6. What effect do crops have on the 

 supply of nitrogen in soils? 7. What Is denitrification? 

 8. How do dry soils lose nitrogen? 9. How do wet soils 

 lose their nitrogen? 10. Why do tobacco lands often suffer 

 a greater loss of nitrogen than wheat lands? 11. Why do 

 cotton lands suffer a loss of nitrogen? 



