QUESTIONS 383 



3. Legume that grows well only on good soils : Alfalfa. 



Lime Requirements of Legumes. Certain of our most im- 

 portant legumes require a good supply of lime in the soil, notably 

 alfalfa and red clover. Many are indifferent to lime and others 

 prefer an acid soil. The matter has never been clearly worked out, 

 and available data are conflicting, but the common legumes may be 

 roughly grouped : 



1. High in lime requirements: Alfalfa, red clover, sweet clover. 



2. Low in lime or slightly deficient in lime: Field beans, soy 

 beans, vetches, peas, white clover, alsike clover. 



3. Soil may be very deficient: Cow peas, lespedeza or Japan 

 clover, burr clover. 



4. Prefer acid soils : Florida beggar weed and velvet bean. 



It is not intended to mean that the plants actually prefer the con- 

 ditions indicated in each group, but will do fairly well in such con- 

 dition. For example, alsike clover responds to lime and prefers a 

 limestone soil (Fig. 167), but yet will grow fairly well on soil lacking 

 in lime, where red clover will fail. 



QUESTIONS 



1. State the important facts about the legume family. 

 2. How is the pea family separated from the rest? 



3. From what does it derive its name, legume? 



4. Describe the clover family. 



5. The alfalfa family. 



6. How many important families of legumes are grown for forage? 



7. Name as many as you can. 



8. Compare legumes and grasses in depth and amount of root. 



9. What per cent of root in the surface six or eight inches? 



10. Compare the root system of timothy and red clover. 



11. What proportion of the plant is root? 



12. Compare legumes and grasses in chemical composition. 



13. Compare legumes and grasses with grain crops as to effect on produc- 



tivity of soil. 



14. Compare legumes and grasses as to effect on soil exhaustion. 



15. Compare legumes and grasses as to time of harvesting for maximum 



yield for best quality. 



16. How long has the value of legumes been known? 



17. Early theories as to why they were valuable. 



18. When was the secret of their value discovered? 



19. By what means do they acquire nitrogen from the air? 



20. Do all legumes have the same bacteria? 



21. Tell how to inoculate with soil. With artificial culture. 



22. What is natural inoculation? 



23. Is inoculation equally important for all legumes? 



24. State the variation of legumes as to soil requirements; as to lime re- 



quirements. 



