324 SOIL PHYSICS AND MANAGEMENT 



33. Give conclusions from table on page 322. 



34. What effect did cropping have on drainage? 



35. What is fallowing? 



36. Why should there be such a large loss of nitrates from the fallowed 



land? 



37. What is denitrification ? 



38. Under what conditions does it occur? 



REFERENCES 



1 Brown, P. E., Research Bulletin 8, Iowa Station, Bacteria at Different 

 Depths in Some Typical Iowa Soils, p. 280. 



* Schldsing, Compt. Kend. Academy of Science, Paris, vol. Ixxvii, pp. 

 203-253. 



*Deherain, Compt. Rend. Academy of Science, Paris, vol. cvi, 1893, pp. 

 1091-97. 



4 Chester, Frederick E., Bulletin 98, Department of Agriculture, Penn- 

 sylvania, 1902, p. 25. 



"Dumont, Compt. Rend. Academy of Science, Paris, vol. cxxv, 1897, pp. 

 469-72. 



Deherain, Noted by Hall, A. D., The Soil, 1912, p. 228. 



