Sorghum & Sudangrass

Summary

Common Name

The common name is sorghum, Sudangrass, or Sudan grass (Marks and Townsend, 1973).

Scientific Name

Sudangrass and sorghum are both in the species Sorghum bicolor (L.) Moench (Munz, 1973; Fribourg, 1985). Sudangrass was formerly Sorghum sudanense (Piper) Stapf. (Hitchcock, 1971) and Sorghum vulgare var. sudanese Hitchcock (Marks and Townsend, 1973).

Cultivar

According to the Southern Seedsmen's Association (1992), there are sorghum varieties used for forage, grain, syrup, and wild game feed.

The chief races or varieties of sorghum in the United States are termed sorgo, kafir, durra, milo, feterita, shallu, kaoliang, and broomcorn (Hitchcock, 1971).

Seed Description

Fribourg (1985) stated that there are about 25,000-60,000 seeds/kg for grain sorghums, and about 120,000-150,000 seeds/kg for forage sorghums. Seeds may be white, yellow, red, or brown, with the darker-colored seed being higher in tannin.

Seedling Description

No information is available in this database on this topic.

Mature Plant Description

According to Fribourg (1985), sorghum is a coarse, erect grass with variable growth characteristics, and height ranging from 0.45 to over 5 m. Some cultivars tiller early, whereas others do not until maturity or when the plant is damaged. The inflorescence is a panicle containing up to 6,000 fertile spikelets. The plant is usually self pollinated.

Temperature

Sorghum is frost sensitive (Johnny's Selected Seeds, 1983).

Geographic Range

Several races of sorghum were introduced from Africa (Hitchcock, 1971).

Water

Sorghums can grow where precipitation is as low as 400-650 mm, but do better with more water; drought may induce temporary dormancy.

Nutrients

No information is available in this database on this topic.

Soil pH

Sorghum tolerates very high pH (8.0 to 9.0) and is often used in rotation with barley to reclaim alkaline ground. (Fred Thomas, pers. comm.)

Soil Type

Sorghum does best on fairly fertilie soil (Johnny's Selected Seeds, 1983).

Shade Tolerance

Bugg & Dutcher (1989) reported that cv 'Kow Kandy' performed well in the partially shaded understory of a mature pecan orchard in southern Georgia.

Salinity Tolerance

Sorghum tolerates very high pH and salinity. It is used to reclaim sodic ground. (Fred Thomas, pers. comm.)

Herbicide Sensitivity

No information is available in this database on this topic.

Life Cycle

Sorghum is a summer annual (Johnny's Selected Seeds, 1983), and a C-4 plant (Bugg, pers. comm.).

Seeding Rate

Sorghum should be seeded at 30-40 lbs/acre (Johnny's Selected Seeds, 1983), or 10-20 kg/ha (Fribourg, 1985).

Seeding Depth

Sorghum should be seeded at a depth of 1 inch (Johnny's Selected Seeds, 1983), or 1-5 cm (Fribourg, 1985).

Seeding Method

Drill or broadcast and incorporate by harrowing (R.L. Bugg, pers. comm.).

Seeding Dates

Seed in spring after the last threat of frost (R.L. Bugg, pers. comm.). Seed when soil temperature reaches 60 F or more, usually May 1. Earlier seedings will be overtaken by weeds if the weather is cool. (Fred Thomas, pers. comm.)

Inoculation

These are grasses and generally require no inoculation.

Seed Cost

Sudangrass: $0.35 to $0.40 per pound. Sorghum and Sudangrass: $0.60 to $0.80 per pound. Sorghum: $1.00 to $1.20 per pound.

Seed Availability

The Southern Seedsmen's Association (1992) listed 15 suppliers of forage sorghums and 54 of sorghum X sudangrass hybrids.

Days to Flowering

In southern Georgia, the sorghum X sudangrass hybrid called 'Kow Kandy' sown on July 4 began flowering on August 24 and reached full flower on September 21 (Bugg and Dutcher, 1989).

In Massachusetts, the grain sorghum cv RS-610(TE-66) sown on May 7 began flowering on August 3 and reached peak flowering by August 18 (Bugg and Ellis, 1990).

'Piper' sudangrass planted in June in Davis typically flowers (anthesis) in about 65 days. (Mark Van Horn, pers. comm.)

Days to Maturity

No information is available in this database on this topic.

Seed Production

No information is available in this database on this topic.

Seed Storage

No information is available in this database on this topic.

Growth Habit

These are erect grasses (R.L. Bugg, pers. comm.). Some dwarf sorghum cultivars are only 40 inches high at maturity. (Mark Van Horn, pers. comm.)

Maximum Height

In southern Georgia, the sorghum X sudangrass hybrid called 'Kow Kandy' attained a maximum height of about 1.60 m (Bugg and Dutcher, 1989).

In Massachusetts, the grain sorghum cv RS-610(TE-66) attained a maximum height of about 1 m (Bugg and Ellis, 1990).

'Piper' sudan is typically 7 to 8 feet tall at anthesis. 'Evergreen' sorghum sudangrass will attain ten feet. (Mark Van Horn, pers. comm.)

Root System

As with most grasses, these have fibrous root systems (Bugg, pers. comm.).

Kutschera (1960) reported that Sorghum halepense generally roots to a depth of 124 cm.

Establishment

Can easily be planted to moisture with no subsequent water for 2-3 weeks. (Mark Van Horn, pers. comm.)

Maintenance

Fairly drought tolerant. Sorghum planted in 30-40 inch beds may require one cultivation. Sudangrass is very competitive with weeds. (Mark Van Horn, pers. comm.)

Mowing

Sorghum or sudangrass can be flail chopped (Jeff Main, pers. comm.). Three to four cuttings of sudangrass may be cut and baled annually, usually about 60 days apart. (Mark Van Horn, pers. comm.)

Incorporation

Very high C/N ratio, therefore slow decomposition. (Mark Van Horn, pers. comm.)

Harvesting

Typically harvested with grain harvesting equipment. (Mark Van Horn, pers. comm.)

Equipment

Sorghum or sudangrass can be flail chopped (Jeff Main, pers. comm.).

Uses

Sorghum is grown for organic matter, to enhance soil life, and weed suppression (Johnny's Selected Seeds, 1983); it also makes high quality livestock forage or silage livestock (Fribourg, 1985).

Mixtures

De Queiroz and Galwey (1987) grew five sorghum (S1006, 2219 B, CSH 5, CSH 6, and Ethiopian landrace E 35-1) and 2 cowpea varieties (the semi-erect C 152 and the spreading, later-maturing GFC 4) as sole crops and in sorghum-cowpea bicultures during the dry season. There was no significant effect of cowpea variety on sorghum yield, nor of sorghum variety on cowpea. This will probably not be the case for rainy-season plantings, in which sorghum tends to shade the intercrop more completely. For dry-season plantings, the authors suggested that a single cowpea variety might be used to evaluate sorghum performance in biculture.

Biomass

Sorghum produces a large volumes of biomass in 2-3 months (Johnny's Selected Seeds, 1983). Sorghum-sudangrass hybrids produce more biomass than does sudangrass (Schonbeck, 1988). When sorghums are cut for hay, each of 5 harvests can yield 2 Mg/ha or more. Total dry matter production by sorghum or pearl millet can range from 15-20 Mg/ha (Fribourg, 1985).

N Contribution

Smith and Sharpley (1990) found that incorporation of non-legume (high C:N ratio) residues (e.g., corn) led to depression of N availability greater than that for surface residues. N availability was in this order for crop residues: alfalfa > peanut > soybean > oat > sorghum > wheat > corn.

Non-N Nutrient Contribution

No information is available in this database on this topic.

Effects on Water

Sorghum requires more water than pearl millet (R.L. Bugg, pers. comm.)

Effects on Microclimate

Relative humidity will be high in a well-irrigated sudangrass field when it is 6 feet tall. (Mark Van Horn, pers. comm.)

Effects on Soil

Sudangrass and sorghum-sudangrass hybrids are fast-growing summer annuals that can be used to suppress weeds or provide mulch or soil structural improvement (Schonbeck, 1988).

Zhang and Hendrix (1995) in Georgia conducted laboratory microcosm studies on carbon flow as affected by the epigeic earthworm Lumbricus rubellus and the endogeic earthworm Aporrectodea caliginosa vs. microcosms lacking earthworms. Sorghum leaf litter was labeled with 13C, whereas cereal rye fine roots and root exudates were labeled with 14C. the sorghum leaves were placed on the microcosm soil surfaces; cereal rye portions were included in the soil. Mason jars containing 500g of the 14C-labeled soil served as microcosms. There were three treatments, each replicated 5 times: (1) 14C soil and 13C litter; (2) 14C soil and 13C litter and 4 adult L. rubellus; and (3) 14C soil and 13C litter and 4 adult A. caliginosa. After 37 days of incubation at 18° C, destructive sampling terminated the experiment. Key findings included: (1) Earthworms decreased translocation of soil C into leaf litter, possibly by reducing fungal hyphal connections; (2) the epigeic earthworm (L. rubellus) preferentially ingested 13C litter, whereas the endogeic A. caliginosa fed preferentially on the 14C-labeled soil. The former increased surface litter loss by ~15% and the latter by ~11% vis a vis the control microcosms.

Effects on Livestock

Sorghums produce high volumes of high quality forage during the warm-season (Fribourg, 1985). Sudangrass and sorghum-sudangrass hybrids produce toxic levels of cyanide while young, so should only be grazed when more mature (Schonbeck, 1988).

There is substantial documentation regarding prussic acid poisoning to livestock with new growth or frosted sudan or sorghum x sudan. This is the one major problem in some livestock situations. (Fred Thomas, pers. comm.)

Effects on Workers

No information is available in this database on this topic.

Pest Effects, Insects

In southern Georgia, in an experimental grove of pecan (Carya illinoensis [Wangenh.] K. Koch [Juglandaceae]), Bugg and Dutcher (1989) surveyed potential "insectary crops." Thirteen prospective warm-season cover crops were evaluated for associated aphids and entomophagous insects; an additional 11 crops or mixtures were considered in unreplicated plots. A Sorghum X Sudangrass hybrid (Sorghum bicolor [L.] Moench cultivar 'Kow Kandy', Sorghum hosted corn leaf aphid (Rhopalosiphum maidis [Fitch]) and greenbug (Schizaphis graminum [Rondani]). Corn leaf aphid was first observed on sorghum, during the week of July 19, and colonies were observed on spikelets of sorghum from early September until frost in late November. After pecan leaf drop in October, O. v-nigrum was often observed feeding on this aphid. Sorghum can also harbor abundant southern green stinkbug, Nezara viridula, and leaffooted bug, Leptoglossus phyllopus (L.)(Bugg, pers. comm.), both of which are kernal-feeding pests of pecan.

On Cape Cod Massachusetts, Bugg and Ellis (1989) evaluated insect faunae of ten cover crops grown in two replicated trials. Five crops were assessed in the principal experiment: (1) Faba bean, Vicia faba L. cv 'Ipro' (Fabaceae); (2) Hairy vetch, Vicia villosa Roth (Poaceae), planted in mixture with rye, Secale cereale L. cv 'Aroostook' (Poaceae); (3) Annual white sweetclover, Melilotus alba Desrousseaux var. annua Coe cv 'Hubam' (Fabaceae); (4) Grain sorghum, Sorghum bicolor (L.) Moench cv RS-610 (TE-66) (Poaceae); and (5) Buckwheat, Fagopyrum esculentum Moench (Polygonaceae). Sorghum featured high densities of corn leaf aphid, Rhopalosiphum maidis (Fitch), and seven-spotted lady beetle, Coccinella septempunctata L. during the first three weeks of July.

Pest Effects, Nematodes

Marks and Townshend (1973) found that sudan grass and buckwheat (Fagopyrum esculentum Moench) harbored particularly-high densities of root lesion nematode (Pratylynchus penetrans).

Rhoades (1983) found that sting nematode was abundant and caused reduced yields for cool-season vegetables following cover cropping with a sorghum X Sudan grass hybrid.

Pest Effects, Diseases

No information is available in this database on this topic.

Pest Effects, Weeds

Sudangrass and sorghum-sudangrass hybrids are fast-growing summer annuals that can be used to suppress weeds or provide mulch or soil structural improvement (Schonbeck, 1988).

Pest Effects, Vertebrates

No information is available in this database on this topic.