34 THE ESSENTIALS OF AGRICULTURE 



growing season by a twenty-acre field of oats? What relation does this 

 bear to your annual rainfall? 



10. In what ways might a layer of leaf hairs affect the amount of water 

 within a plant ? 



11. What is the effect of a growth of weeds upon soil water? 



12. Why is starch rather than sugar a more advantageous form for 

 stored food? 



13. What is the importance of protein foods? Where is most of the 

 protein of plants stored? 



REFERENCES 



BERGEN and CALDWELL. Practical Botany, chap. ii. Ginn and Company. 

 BRIGGS and SHANTZ. The Water Requirements of Plants, Bulletin 284. 



and Bulletin 285, Bureau of Plant Industry, United States Department 



of Agriculture. 

 DUGGAR, B. M. The Physiology of Plant Production. The Macmillan 



Company. 

 The Weed Factor in the Cultivation of Corn, Bulletin 257, Bureau of 



Plant Industry, United States Department of Agriculture. 



