Purdue University Department of Agronomy

Corny News Network

Originally published 2003, Updated June 2008
URL: http://www.kingcorn.org/news/timeless/LatePlantGrainSorghum.html

Grain Sorghum Considerations for Late Planting in Southern Indiana

R.L. (Bob) Nielsen, Bill Johnson, & Glenn Nice
Purdue Univ. Extension Specialists
West Lafayette, IN 47907-2054
Email: rnielsen at purdue.edu, wgj@purdue.edu, gnice@purdue.edu

Grain sorghum, sometimes called “milo”, can be a viable late-planting option for southern Indiana farmers faced with late planting dilemmas, especially where fields have already been treated with certain corn herbicides. What are the opportunities and risks involved with switching from corn to sorghum? What cultural practices are followed in producing sorghum?

Opportunities Source of Image: http://www.ksgrains.com/kgsc/

Grain sorghum is an acceptable crop alternative to corn for hog and cattle producers who otherwise may have to purchase corn this fall. The feed value of grain sorghum approaches or equals that of corn, especially that of yellow endosperm sorghum hybrids.

Grain sorghum is well suited to those soils or conditions often considered marginal for corn. Sorghum can be planted later than corn and still yield reasonably well. Sorghum performs more consistently than corn on light, well-drained, often droughty soils as well as on soils that are prone to flooding or lengthy periods of soil saturation. Sorghum is also more tolerant to mid-summer drought conditions than is corn.


Potential sorghum growers need to be aware that learning the ins and outs of producing a crop they’ve never grown before can be daunting in normal growing seasons, let alone in an unusually delayed planting season that some are experiencing this year. Because of this, growers faced with feed grain shortages this fall and winter may want to consider planting to soybean instead and using the grain sale revenue to purchase their feed grain later.

Grain sorghum grown for the cash grain market can be risky due to limited market availability. In southern Indiana, marketing opportunities are primarily along the Ohio River. Growers should attempt to "nail down" a contract to sell their intended grain before venturing into sorghum production.

Herbicide selection for use in grain sorghum is generally more limited than for corn. If Lasso or Dual herbicides are already applied to your fields, then seed sorghum with a commercially applied seed safener should be planted. Otherwise, serious herbicide injury could occur.

Ripening heads of grain sorghum can be very attractive to a number of bird species. Consequently, production of grain sorghum near areas with large populations of birds (typically, urban areas) invites bird feeding on the exposed heads and significant grain damage and yield loss.

Be aware that availability of sorghum seed may be limited simply because sorghum is not a widely-grown crop in Indiana and seed dealers will likely need to transport seed sorghum in from other areas of the U.S.

Field dry-down of sorghum grain can be slow and unpredictable. Several weeks of rain or high humidity in the fall can result in sprouted, moldy, low-quality grain as well as excessive losses due to stalk lodging, grain shattering, and bird feeding.

If mechanical drying is necessary for storage of sorghum, be prepared for frustration. Air movement through sorghum will be 25 to 40% slower than through corn because the sorghum's smaller kernels pack closer together and sorghum tends to have more foreign matter in it.

General Cultural Practices

Hybrid Selection. Hybrids suitable for planting from late May through early July must be early enough in maturity to complete dry matter accumulation prior to a killing fall frost. As with corn, there is no industry-wide standard for describing hybrid maturity in grain sorghum. The accompanying table lists relative hybrid maturities for several areas of southern Indiana for several planting periods. Consult your seed dealer for specific recommendations for your area and planting conditions.

In addition to maturity factors, select hybrids with yellow endosperm characteristics because of their superior feeding value. Select hybrids with good stress tolerance. Depending on your herbicide program (see the following herbicide sections), you may need to select hybrids treated with chemical seed safeners.

Planting Depth. Grain sorghum seed is very small compared to either corn or soybeans, averaging about 16,000 seeds per pound. Therefore, good seed to soil contact is important for uniform and rapid germination. Planting depth should only be about one inch in most soils, up to 2 inches in sands.

Row Spacing. Grain sorghum grown this late in the season should be planted in narrow rows if possible. Narrow rows encourage rapid canopy closure and the subsequent shading will help reduce soil moisture evaporation and improve weed control. Use a grain drill with effective furrow closure wheels, or planters with 15- to 20-inch row units. Either would be preferable to 30-inch or greater row spacing.

Seeding Rates. Necessary equipment for row crop planters would include 60 cell milo plates (plate planters), sorghum cups (Deere), special drums (Case-IH Cyclo), or sorghum seed disks (air and vacuum planters). Harvest populations should be approximately 60,000 to 100,000 plants per acre for lower and higher productivity soils, respectively.

To achieve such harvest populations, figure on seeding rates of about 86,000 to 143,000 seeds per acre (assuming 70% field emergence). Be sure to check the seed size and adjust planted pounds per acre accordingly. At 12,000 seeds per pound, these seeding rates equal 7.2 to 11.9 pounds per acre. At 16,000 seeds per pound, these seeding rates equal 5.5 to 9.0 pounds per acre. Time spent on calibrating your planter or drill to achieve accurate seed drop is time well spent.

Corn Herbicides Already Applied to Fields. Where corn herbicides have already been applied to fields, growers should be cautious when grain sorghum will be planted instead because of the risk for crop injury.

Postemergence Herbicides Registered For Use With Grain Sorghum. Consult the Purdue/Ohio State "Weed Control Guide for Ohio and Indiana" (http://www.btny.purdue.edu/Pubs/WS/WS-16/GrainSorgHerbRating.pdf) or your local herbicide supplier for specific details on weeds controlled.

Fertility Needs. Sorghum’s nitrogen needs are similar to those of corn. For sorghum following soybean, figure 1 lb. of actual nitrogen per bushel of expected yield. For sorghum following corn or wheat, figure 1.2 lb. of actual nitrogen per bushel of expected yield. Since expected grain yields of sorghum planted from mid-June to early July in southern Indiana range from 70 to 110 bushels per acre, the crop’s total nitrogen needs will be 70 to 110 lbs N for sorghum following soybean and 84 to 132 lbs N for sorghum following corn. If nitrogen has already been applied to a field that was subsequently subjected to extensive rainfall and flooding, some loss will have occurred due to denitrification or leaching. Nitrogen losses from fertilizer applications prior to April 1 may be greater than 50%.

Roguing. Be prepared for off-type sorghum plants that may occur in a field of grain sorghum. These are natural in many sorghum hybrids. Most are genetic mutants with similar grain heads, but taller than normal. Others with off-type grain heads should be removed (rogued) from the field to reduce the risk of volunteer sorghum “weeds” coming back next year.

Harvesting. As with corn, grain sorghum is physiologically mature (maximum grain dry weight) at about 30 % grain moisture. Minimal harvest loss and seed damage occurs when harvested at grain moistures of about 20 percent. Achieving this grain moisture by field dry-down under Indiana rainfall and humidity conditions may be risky. Be prepared for frustration!

For More Information

At the risk of offending or neglecting some seed companies, brand names to consider for seed sorghum in Indiana include Dekalb, Asgrow, NC+, Pioneer, Garst, Golden Harvest, Mycogen, and Triumph. Talk to your local seed representative or company agronomist for more information about the risks, opportunities, hybrid maturity selection criteria, and other concerns regarding grain sorghum production for delayed planting in southern Indiana.

Related References

Sorghum Management Information. 2008. Purdue Univ. Agronomy Extension. [On-line]. Available at http://www.agry.purdue.edu/ext/sorghum/index.html [URL accessed 6/4/08].

Loux, Mark M., Anthony F. Dobbels, Jeff M. Stachler, William G. Johnson, Glenn R.W. Nice, and Thomas T. Bauman. 2008. Weed Control Guide for Ohio and Indiana. Purdue Univ. and Ohio State Univ. [On-line]. Available at http://www.btny.purdue.edu/Pubs/WS/WS-16/GrainSorgHerbRating.pdf [URL accessed 6/4/08].

Sorghum Seed Suppliers: [URLs accessed 6/3/08]