IRRIGATION OF CEREALS 263 



Atlantic States, the alluvial lands along the Mississippi, 

 and in southwest Louisiana and southeast Texas. Upland 

 rice may be grown wherever corn does well, and by 

 methods similar to those used in the culture of summer 

 oats. 



Rice fields are divided by field levees into tracts of 

 varying sizes, depending on the slope of the land and the 

 depth of water to be applied. When the water is to stand 

 over the field from 6 to 12 inches deep, the levees are 

 made from 12 to 18 inches high; they should, hi fact, be 

 just high enough to retain the water at the depth decided 

 on. If the levees are too large, the resulting vegetation on 

 them is a source of annoyance. The method of irrigation 

 is necessarily the method of checks. 



Immediately after seeding, the land is flooded for a 

 few days. When the plants are 6 to 10 niches high, they 

 receive the first irrigation. From that time the water is 

 made to stand on the land to a depth of 3 to 6 niches until 

 the grain is in the dough, or about two weeks before har- 

 vest, when the water is drained off and the crop left to 

 ripen. The irrigation water is nearly always pumped from 

 lower levels into the checks, and the ground water is 

 very near the surface, so that it is not a difficult matter 

 to keep water standing on the soil for any desired length 

 of time. The length of the irrigation season varies from 

 two to three months, with an average of about seventy 

 days. 



It might be supposed, from the fact that rice fields are 

 thus covered with standing water, that large quantities of 

 water are necessary for rice-production. The careful 

 investigations of the Office of Experiment Stations show 

 that only from 12 to 18 inches of water above the rainfall 

 are really used by the plant. In one series of experiments, 



