Iowa Farmer Today
08-26-06
Dry conditions highlight hybrid interaction with soil
By Tim Hoskins, Iowa Farmer Today
Eastern Iowa’s drought conditions in 2005 and Western Iowa’s weather stress this year could see similar results — wide yield differences from different soil types.
It is not uncommon to see yield differences in corn hybrids or yield interactions between hybrids, says Roger Elmore, Iowa State University Extension corn specialist.
While yield differences are straightforward, interaction occurs when there is a relative yield difference between two hybrids on the same soil.
For example, he says hybrid A yields 200 bu./acre and hybrid B yields 180 bu. in part of field. It is an interaction if hybrid B yields 200 bu. and hybrid A yields 190 bu. in another part of a field.
However, it is not an interaction if hybrid A yields 210 bu. and hybrid B yields 190 bu. in different areas of the field.
“That happens all the time,” Elmore says.
He says corn breeders know interaction occurs. However, it is not known what causes the phenomenon.
One large factor that could cause wide yield swings or interactions between hybrids is differences among soils and how crops interact with them.
Some differences also could come from the hybrids.
Elmore says some of the major seed companies select hybrids that perform well over many states or the entire Cornbelt.
However, the different soils and environments are where some of the regional seed companies could fill niche, he says.
Bob Miller, president of Miller Hybrids in Iowa City, says his company does more research on a representative sample of soils for Eastern Iowa than larger seed companies do and uses multiple replications.

Miller, who farms and was a corn breeder for a major seed company, says many of the larger companies conduct research on the best flat, black-soil fields they can find.
In Eastern Iowa, Miller says drought and disease are key environmental factors influencing hybrid performance. Farther west, drought becomes a larger concern.
As you move east, disease becomes a larger concern.
Miller uses more replications that hone in on detailed information about the field.
In addition to testing and breeding efforts, he says hybrid selection plays a role.
He says some companies might not offer an ideal hybrid that would be fit for a particular location based on environment factors such as soils and climate.
The hybrid might not have enough sales volume for some seed companies to offer it. However, other seed companies could offer the same hybrid.
In addition to seed companies deciding which hybrids to offer, farmer hybrid selection could make a difference.
For example, Miller says farmers with lighter soils might want to consider a hybrid that has more of a vertical root system, while excellent soils may favor a hybrid with a more horizontal root system.
Elmore says it is a good idea to plant a handful of hybrids in the same field, to spread risk.
Some hybrids have potential for yields while others will be good performers under adverse growing conditions, he says.
“Each hybrid has its own niche.”