Introduced to the United States from Africa in the 1700s, sorghum includes several cultivated grasses with many species and sub-species. In the 1850s, Black Amber or “Chinese sugarcane,” was brought into North America via France. Since that time, other varieties have been introduced from abroad and grown domestically. Sorghum grain now ranks fifth in cereals in terms of worldwide production.
Similar to corn in appearance and growth in the early stages, grain sorghum has more branched roots and tillers and is cultivated for grain production and forage. Prior to the 1940s, grain sorghums were 5 to 7 feet tall, which posed difficulties for harvesting. Today’s sorghum crops have dwarfing genes that limit their height to between 2 and 4 feet. Sorghums self-fertilize but can cross pollinate. A warm-season crop, it can endure the stress of heat and moisture better than other crops, and is widely grown in South Dakota, Colorado, Oklahoma, Nebraska, Kansas and Texas. Extreme high temperatures coupled with drought can reduce yields.
A large, warm-season annual grass that is closely related to the grain variety, forage sorghum stands out for drought tolerance in comparison to corn. The minimum temperature for growth is approximately 60 degrees Fahrenheit. During growing season, when temperatures range between 75 and 80 degrees Fahrenheit, forage sorghum produces its highest yields. According to Glen Cauffman, manager of farm operations and facilities at Penn State, “It is of interest as a biomass energy crop.” An investigation of forage sorghum as a rapid-growing annual has revealed that it can fit into traditional crop rotation on short-term timetable and still yield 5 to 10 tons per acre of dry matter.
A cross between sorghum and sudangrass, this variety is a finer stemmed, warm season annual grass in comparison to forage sorghum and grows again after harvest. Used for green chop, grazing, silage and hay, sorghum-sudangrass can grow up to 15 feet and has been adapted throughout the United States and Canada. Performing best in well drained soils, it withstands drought and requires 1/3 less water than corn. Varieties with the brown midrib gene are easier to digest.
Known as “sorgo,” sweet sorghum traces its ancestry to early Egypt. An annual drought-resistant crop, it can grow up to 15 feet tall and is found primarily in the south-central and southeastern United States. A shell wraps its syrupy pith, which is strewn with vascular bundles. Its smooth, waxy leaves fold and roll up during periods of drought. Self-pollinated, sweet sorghum is planted in rows and fertilized like corn.
Native to India, broomcorn is an upright grass whose seeds appear on the ends of long, straight branches. Cultivated in Europe and America, it grows 6 to 10 feet high and has a jointed stem like a reed. After broomcorn has been harvested and dried, the resulting stiff bristles are bound to form broom heads and brushes. Its seeds are used to fatten sheep and also fed to poultry and horses.