23 
(9) A rotation of crops, including the plowing under of a legume, 
is recommended. It is believed a system can be worked out whereby 
a legume can be grown between crops and then plowed under, thus 
gaining the benefits of the rotation and at the same time permitting 
the growing of two crops of rice annually. 
(10) Rice soils should not be plowed and then allowed to lie fallow 
between crops. Nitrification sets in immediately after aerated con- 
ditions are produced and the nitrates thus formed become converted 
into poisonous nitrites upon resubmergence. or are lost through 
leaching. When no rotation is practiced it is better to leave the land 
unplowed until just before planting the next crop. 
ADDITIONAL COPIES of this publication 
l may be procured from the Superintend- 
ent of Documents, Government Printing 
Office, Washington, D. C, at 5 cents per copy 
