iJJCB 223 



203. Irrigation. — No extensive rice industry has de- 

 veloped in the United States except where irrigation was 

 possible. Irrigation is necessary to large yields and to 

 the most economical production. Lands must be chosen 

 that can easily be irrigated. For this purpose the main 

 quaUties desired are sUght, if any, slope of the surface, and 

 a retentive subsoil. The latter is important so that irriga- 

 tion water may not be lost too rapidly through the soil, and 

 also because such soils, after being drained, best permit the 

 use of heavy machinery in the planting and harvesting of 

 the crop. 



Water for irrigation is supplied in the Louisiana and 

 Texas rice districts by pumping, the source being either 

 adjacent bayous and rivers or an underground supply, 

 found in southwest Louisiana, at no great depth. In the 

 new Arkansas rice-growing region, water is secured from 

 bored wells. In South Carolina, irrigation is accomplished 

 by admitting the water of the rivers when the fresh water 

 is raised by the high tide, while the drainage of rice fields 

 is accomplished at periods of low tide. 



After a supply of water has been provided and brought 

 to the highest part of the fields by a system of canals, low 

 levees must be constructed, chiefly with the plow, so as to 

 maintain the water at almost a uniform depth through- 

 out a given section of the field. This should range 

 between 3 and 6 inches on any one section of the field 

 (Fig. 113). Variations in the depth of irrigation water 

 cause unevenness in the time of maturing and hence injury 

 to the quality of the product. 



204. Irrigation practice. — In Louisiana, the drained 

 fields having been sown by the use of a grain drill, the 



