We’ve been talking all year about the big splash that grain sorghum has made in the Carolinas. Well, big splashes come with big rings of effect, and one of them seems to be showing up in the next wheat crop. Dr. Randy Weisz and Dr. Ron Heiniger have been working on production methods for producers that want to follow sorghum with wheat. Dr. Ron Heiniger:
“We have been gathering information on the effects of sorghum residue on wheat growth. There are some things that growers should be aware of and some things that we are concerned about to get good wheat.”
Heiniger’s first recommendation:
“The first important step is to burn down the sorghum as quickly as possible. The big issue is growing root, meaning that the sorghum wants to keep on growing because it’s a perennial. You want to stop that from happening. That rooting can be a source of problems later on.”
And Heiniger’s second recommendation for planting wheat behind sorghum:
“You want to give the sorghum time to die and decay. You want to put as much space as you can between killing the sorghum and planting the wheat. Finally, anything you can do to help the wheat along, nitrogen or some fertilizer, because sorghum has a lot of residue. This means that the microbes are going to feed on that carbon and take up some nitrogen, so there will be less available to the wheat.”
Heiniger and Weisz have published a short informational brochure SEE BELOW:
NC State corn and sorghum specialist Dr. Ron Heiniger on Inside Agriculture
Ron Heiniger and I have been getting lots of questions about planting wheat following sorghum. Here is what we know about doing this:
Sorghum leaves a chemical in the soil that can hurt wheat. Little is known about it, and tests have never been done in this part of the county. So we have little data to go on. The problem is most severe in no-till wheat following sorghum. Some reports have shown up to a 25% yield reduction when no-till wheat follows sorghum. Some reports have shown less. Tillage helps. Yield reductions in tilled wheat following sorghum have ranged up to 10%.
Growers who want to plant wheat following sorghum should know that this might be a problem for them. Because very little research has been done in this area, it is difficult to make recommendations to assist folks who want to do this. But, here are several suggestions that may help.
1) Use glyphosate to kill the sorghum prior to harvest. If the sorghum is left alive and starts to regrow after harvest, the new roots will continue to exude the toxic compound.
2) Use tillage to incorporate sorghum residues and hasten their decomposition.
3) Delay wheat planting. This is tricky. Delaying wheat planting can in-and-of-itself reduce wheat yield, but it may also help to allow the toxic compounds to decompose.
4) Make sure the wheat is treated to high pre-plant fertility levels. Make sure pre-plant N, P, K, and S are at or above recommended levels.
5) If planting wheat after tillage check stand establishment and watch early tillering. The problems are most likely to show up early in the season and look like either a poor stand, or a good stand that starts to go backwards. Early N in February may help.
6) If planting wheat no-till, watch the wheat plants both early for stand establishment, tillering (and need for February N), and also in the spring!!! Research has shown that the problem may not start in no-till wheat until the spring when plants may begin to turn yellow and abort tillers.
We are learning as we go on this one! Hopefully by next year we will have a lot more concrete information about this.