REFERENCES 435 



QUESTIONS ON THE TEXT 



1. Show that the food supply problem is a dual problem. 



2. State the Malthusian ideas concerning poverty and poor relief. State the 



Malthusian theory of population (increases and checks). 



3. What, according to Malthus, is the most powerful check on population 



in Europe? 



4. Give Malthus's statement concerning United States population. 



5. Criticize this statement of Malthus. 



6. Is or is not the Malthusian theory of population correct? 



7. What are the unknown factors to-day in population increases? 



8. How many years have the fields of Japan and China been cultivated? 



9. How is soil fertility maintained in these older regions? 



10. State briefly the impending danger of a world wheat shortage, as announced 



by Sir William Crookes. 



11. What is meant by soil fertility? 



12. What are the three chief plant foods subtracted from the soil by cropping? 



13. The average acre of soil in America contains how many pounds of each 



of these three? 



14. An average wheat crop removes how many pounds of each of these three 



per acre? 



15. State briefly the claims made by Liebig as to the meaning and danger 



of soil exhaustion. 



16. How did the critics, especially Conrad, answer Liebig? 



17. Where, according to Conrad, does agriculture reach its greatest perfection? 



18. Summarize the conclusions on the soil exhaustion 'question. 



19. What is meant by the Soil Destruction question? How are soils destroyed? 



20. How serious is the question of soil destruction in the United States? 



21. Which is the more fundamental problem, the soil or the man on the soil? 



Why? 



22. Give an account of the English farm, showing how increasing returns 



were secured. 



23. Give an account of the Martin farm, showing how the soil fertility prob- 



lem was solved. Account for the increasing returns on this farm. 



24. Summarize final conclusions as to soil exhaustion problem. 



QUESTIONS SUGGESTED BY THE TEXT 



1. Give the "Trench System" of restoring soil fertility as practised at 



Allahabad, India. 



2. Describe the methods in use in Japan, Korea, and China for maintaining 



soil fertility. 



3. Give the principal sources of commercial nitrogen; phosphorus; potash. 



4. What is the outlook for the future supply of these three forms of plant food? 



5. Cite examples that have come to your notice of "worn-out" land being 



restored to fertile condition by scientific farming. 



6. Cite examples of fertile lands that have been reduced to "waste lands" 



by bad methods of treatment. 



REFERENCES 



1. MALTHUS, REV. T. R.: "An Essay on the Principle of Population," 

 7th edition. London, 1872. 



2. KING, F. H.: "Physics of Agriculture." 

 3. : "The Soil." 



4. : "Farmers of Forty Centuries." Madison, Wisconsin, 1911. 



5. ROBERTS, I. P.: "The Fertility of the Land." 1898. 



6. LIPMAN, J. G.: "Bacteriology in Relation to Country Life." 1908. 



