4 Farmers' Bulletin 1126.

numerous than those of Johnson grass, giving the grass a much more favorable appearance as a hay plant. The most important difference, however, is that the aggressive underground stems, or rootstocks, with which Johnson grass is equipped, are entirely absent in Sudan grass. This striking difference is shown clearly in the accompanying figure illustrating young seedling plants of the two grasses (fig. 2). Sudan grass, like the cultivated sorghums, never develops anything but fibrous roots, therefore it can not become an obnoxious weed as the perennial Johnson grass does. Furthermore, it has shown no tendency to persist in fields as an annual weed through volunteer seedings. When it has plenty of room the grass tillers very freely. It is not uncommon to find over 100 stems arising from one crown. This decided tendency to tiller is most apparent afteï the first cutting, and usually makes the hay from the second cutting of finer texture than that from the first.

CLIMATIC REQUIREMENTS.

Sudan grass, like sorghums, does best in a warm climate. In favorable seasons, where the growing period is long, as many as four cuttings can be obtained in one year. As in the case of all other crops, in determining the regions of greatest importance, climatic and soil conditions are linked with the acuteness of the need for such a crop. The principal regions of production in the United States are shown on the map (fig. 3), as follows : Region i.—Two or three good cuttings of hay are secured without irrigation in this region, the yields varying from 2 to 4 tons to the acre. This is the region of its greatest importance because of the need for a better hay grass in these States. Profitable seed yields are secured west of the ninety-eighth meridian only, the sorghum midge usually preventing seed formation in the more humid district east of this meridian.

Region 2.—Sudan grass thrives here almost as well as in region 1, making good yields both of hay and of seed. Timothy, clover, and alfalfa, however, meet the hay requirements of this region so fully that Sudan grass is valued chiefly as a pasture and catch crop or for limited culture on soils not suited to these forage crops.

Region 3.—This comprises the region west of region 2, where the rainfall is too low for the successful cultivation of timothy and clover. Sudan grass commonly makes one cutting under such conditions, and in favorable seasons two, yielding 1 to 3 tons <of hay to the acre. Its chief competitors in this region are alfalfa, sorghum, and millet. Alfalfa is preferred to Sudan grass only in the more favored locations, such as river and creek valleys or where irrigation is possible. The better varieties of sorghum, such as Red Amber and Orange; will outyield Sudan grass, but the latter is better suited for pasture purposes, produces a better quality of hay, and is easier to handle with haying machinery. Seed production, though possible in most of this region, is profitable only in the southern part.

Region 4.—Sudan grass yields abundantly both in hay and in seed in all irrigated localities in this region ; yields of 4 tons of hay to the acre are not uncommon on good soils. It is used chiefly to supplement alfalfa in the rations of horses and dairy cattle.

Region 5.—In this part* of the United States Sudan grass is successful only in limited areas. Its failure except in these localities is due either to low temperatures caused by high altitudes or to insufficient rainfall.

Region 6.—In this region, including Florida and the Coastal Plain along both the Atlantic and Gulf coasts, Sudan grass is usually a failure, largely on account of the injury to the foliage caused by red-spot or sorghum blight.

Region 7.—This is a region 100 to 200 miles wide along the northern border of the United States. Sudan grass is not grown extensively in this section because of the cool summers and short growing season.