Posted on Jan 09, 2017
By Brent Bean, Sorghum Checkoff Agronomist
Sorghum planting time is almost upon us. The most common mistake made by new sorghum growers is planting too much seed. Sorghum can compensate for a low population in two ways:
Tillering. When early season growing conditions are good, low plant populations will produce additional stalks at the base of the plant, resulting in a higher number of grain heads at harvest.
Head flexing. We often talk about corn hybrids that can “flex” to produce longer ears, and thus produce more grain under good conditions. Well, sorghum plants have a similar ability in that head size will be larger at low populations when conditions are good.
Low Seeding Rate
Research has consistently shown that sorghum plant populations can vary greatly and produce the same yield. Lower populations will have a higher number of seed per head that offsets the higher number of heads that result from a higher seeding rate.
Here are some of the advantages of a low seeding rate:
- Crop is better able to withstand short periods of drought
- Less lodging
- Typically better head exertion from the leaf whorl improving harvesting efficiency
- More efficient plant in that more resources go to produce grain rather than vegetation (stalks and leaves)
- Possibly less foliar disease because of better air movement between plants
- Less seed cost
Seeding rate should be based on yield goal. Here is a helpful chart.
It should be noted that it is especially important to use a low seeding rate in sandy soils with little water-holding capacity. Seeding rates should be based on seed/acre and not pounds /acre of seed. Sorghum seed can vary from 12,000 to 18,000 seed per pound depending on the hybrid. Seed number per pound will be stated on the seed bag tag.