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June 25, 2008

Extensive spring floods delay Indiana soybean planting

WEST LAFAYETTE, Ind. - As rain-soaked soils begin to dry in Indiana, farmers with soybean acreage left to plant should now be planting mid-season soybean varieties, said a Purdue University expert.

"In general, total rainfall across the southern third of the state is running as much as 10 to 15 inches above normal for the year with extensive flooding," said Purdue agronomist Ellsworth Christmas. "Soybean planting has obviously been delayed and has now been delayed long enough for farmers to consider changing maturity groups."

But because mid-season soybean varieties tend to yield lower than full-season varieties, Christmas suggests planting a few extra.

"Seeding rates should be increased by 15 to 20 percent to promote shading, taller plants, and increased pod height and number of nodes per acre," he said. "This will help offset the reduced yields caused by delayed planting."

Planting later than normal does mean that farmers will be harvesting crops a little bit later, but Christmas said harvest shouldn't be delayed the same amount of time as planting.

"Unlike corn, which requires a certain number of growing degree days to mature, soybeans are more sensitive to day length," he said. "As the day length shortens later in the growing season, soybean maturity speeds up. In general, for each three days planting is delayed, harvest is delayed only one day."

While there is still time for farmers to get their soybeans into the ground, Christmas warned that there does come a point when late becomes too late.

"A commonly used rule of thumb to stop planting soybeans is 90 days prior to the first 32 degree frost for a given area within the state," Christmas said. "This means that the cutoff date for the Bluffton area in northeastern Indiana is June 30, while in the Lafayette area it is July 5. Soybean planting should cease in most of the southern half of Indiana by July 10, except for the southwest corner, where planting can occur up until July 15."

Writer: Jennifer Cummins, (765) 494-6682, cumminsjs@purdue.edu

Source: Ellsworth Christmas, (765) 567-2883, echristm@purdue.edu

Ag Communications: (765) 494-2722;
Beth Forbes, forbes@purdue.edu
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