Sudan Grass. 5 Since its introduction in 1909 Sudan grass has become known in nearly every part of the United States and is now being grown where it was at first thought to be wholly unadapted. Its short growing period permits it to thrive and make good crops of hay as far north as southern Michigan and New York. Throughout the timothy and clover region, though it may never become the leading hay grass, it will be used more and more as a catch crop in place of the millets and for summer pasture. In the Eocky Mountain region (fig. 3, region 5) the results are for the most part unfavorable except in the irrigated valleys. At the higher altitudes untimely frosts and continued low temperatures during the summer months preclude a successful growth. The upper limits of profitable hay production seem to be 6,000 to 8,000 feet in New Mexico, Arizona, and southern California; 5,000 to 6,000 feet in Colorado, Utah, Nevada, and northern California; and 4,000 to 5,000 feet north of those States.

30e., A / \ —r ! / ""/st i i 3 \ y \ O \ h'-mj ( \"\ / / : >y j J>Í* UV-\>\ g\ . 38* Y\G, 3.—Outline map showing the forage value of Sudan grass in different parts of the United States.

The altitudinal limits for seed production are at least 1,000 feet lower, respectively, than those named for hay, because under cool conditions it takes a month or more to mature seed after the crop is ready to be cut for hay.

DROUGHT RELATIONS.

That Sudan grass will grow and produce fair crops in regions of low rainfall has been demonstrated by numerous tests in the Great Plains. Its ability to endure periods of drought is equal, though not superior, to that of the best varieties of sorghum. In the South, where drought is usually combined with extreme heat, Sudan grass yields much better than millet,.but in Montana and the Dakotas millet makes a slightly larger yield.

Experiments have shown that Sudan grass requires a greater amount of water to produce a pound of dry matter than does corn,