IRRIGATION 277 



15. How much water should bo applied to a crop? 



10. Study carefully the proportionate increase of yield for increased appli- 

 cation of water in the table on page 2t>4. 



17. Compare the yield per acre where 7.5 inches were applied with that for 



30 inches. Did the large application pay? 



18. How is water lost from the irrigation canals? 



19. What is the significance of this loss? 



20. How i's this loss prevented ? 



21. How is the water measured? 



22. What are the advantages and objections to surface sprinkling? 



23. What is check-flooding? 



24. Give advantages of furrow irrigation. 



25. Why should the irrigated land lie cultivated soon after irrigation? 



26. Under what conditions is irrigation in humid climates profitable? 



REFERENCES 



1 Widtsoe, J. A., Principles of Irrigation Practice, 1911, p. !)G. 



2 Forbes, K. H., Bulletin 44, Arizona Station, The Kivcr Irrigating Waters 



of Arizona, 1902, p. 100. 



3 Widtsoe, J. A., Bulletin 110, Utah Station, The Production of Dry Matter 



with Different Quantities of Irrigation Water, 1912. Widtsoe. J. A., 

 and Merrill, L. A., Bulletin 117, Utah Station, The Yields of Crops 

 with Different Quantities of Irrigation Water, 1912. 

 'Bulletin 117, Utah, Op. Cit., p. 115. 



5 Widtsoe, J. A., Principles of Irrigation Practice, 1911, p. 337. 



6 Widtsoe, J. A., Principles of Irrigation Practice. 1911. p. 331. 



7 Mosier, .F. (',., and (iustafson, A. F.. Bulletin 181, Illinois Station, Soil 



Moisture and Tillage for Corn, 1915. 



General References. Fortier, Samuel, Yearlwok U. S. D. A.. Methods 

 of Applying Water, 1909, p. 293. McLaughlin, W. W., Farmers' Bulletin 

 399, I'. S. I). A., Irrigation of (Jrain, 1910. Welsh, J. S.. Bulletin 74. Idaho 

 Station, Irrigation Practice, 1914. Hoed ing, F. W.. Farmer*' Bulletin 392. 

 U. S. 1). A., Irrigation of Sugar Beets, 1910. Newell, F. H., Irrigation, 

 1906. 



