6 Farmers9 Bulletin 1126.

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 Rocky 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. 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, sorghum, or millet. Notwithstanding this indicated high water requirement, Sudan grass has been successfully grown as a dry-land crop since 1912, when the first wide distribution of seed took place. As an emergency hay crop and summer pasture no other crop is better suited to conditions in the southern half of the Great Plains.

On the university farm at Davis, Calif., it has been grown with good results as a dry-land crop and is recommended for use in other parts of that State where irrigation water is not available.3

SOIL REQUIREMENTS.

Sudan grass is not at all exacting in its soil requirements. It does best on a rich loam, but it has been grown successfully on almost every class of soil from a heavy clay to a light sand. Where the soil is quite sandy, however, the yield may be expected to be light. Cold, ^vet, muggy soils are particularly unsuited to Sudan grass. Before such soils will grow it, thorough drainage must be provided. Small amounts of alkali in the soil redute the yields markedly and stronger concentrations prevent profitable culture.

s Madson, B. A., and Kennedy, P. B. Calif. Agr. Exp. Sta. Bui. 277, p. 200. 1917.