RICE 359 



the quality inferior to that of irrigated rice. Upland 

 rice is usually planted in rather close drills and culti- 

 vated. These so-called upland varieties succeed better 

 when irrigated. 



442. Climatic adaptations. Rice is a tropical plant 

 but thrives also in semi-tropical regions. It is more re- 

 sistant to extreme heat than wheat, being quite similar 

 to cotton in its climate range. Roughly speaking, the 

 world's rice crop is produced within the area lying between 

 latitude 40 degrees north and south of the equator in both 

 hemispheres. However, its best development is possible 

 only within those regions having a very moist, insular 

 climate. The bulk of the world's rice crop is produced 

 throughout the warmer parts of China, Japan, India, and 

 the Philippine Islands in Asia, Italy and Spain in Europe, 

 the southern United States in North America, Honduras 

 in Central America, and Brazil, British Guiana and Peru 

 in South America. 



443. Irrigation. The most economical production 

 of high-grade rice is possible only in regions where the crop 

 can be flooded with three to six inches of water during 

 most of the growing period. Lands selected for irrigated 

 rice must, therefore, have slight, if any slope, and must 

 be retentive of water. The fields must be laid off in such 

 a manner that the entire surface of each contour or" sub- 

 field will be at practically the same level, otherwise the 

 irrigation water will vary in depth in different parts of 

 the field, and the crop will ripen ununiformly. Where 

 the slope of the land is considerable only small contours 

 are possible. In the level prairie sections each contour 

 often comprises as much as 20 or 30 acres. 



Irrigation water is supplied from rivers, bayous, or wells. 

 Usually large canals are constructed from the water source 



