WEST LAFAYETTE, Ind. – Seed quality for this year’s soybean crop is considerably better than last. However, supplies are going to be tight in Indiana, said Ellsworth Christmas, Purdue University agronomist.
In Iowa and Nebraska, late, dry weather conditions last fall produced poor seed quality, Christmas said.
“Because of this problem, supplies of more popular varieties will be tight since seed from the Eastern Corn Belt will be needed to fill this shortfall,” he said.
Wet conditions in parts of the Eastern Corn Belt at harvest last year caused some seed to develop pod and stem blight.
The seed can be identified and treated with a fungicide before planting to prevent rotting prior to germination, Christmas said.
Early spring weather in recent years has moved some farmers into the field sooner. But Christmas cautions that soybean physiology and growth habits need to be taken into account.
When to plant soybeans.
“When considering the soybean plant and Indiana’s climate, particularly soil temperature, the optimum planting date most years is between May 5 and May 20,” Christmas said.
The ideal soil temperature at planting is 65-70 degrees, Christmas said. Seed will begin to germinate when soil temperatures rise above 50 degrees. Germination is slow below 60 degrees, and can lead to problems.
“Slow germination places the seed and plant under significant stress, resulting in soilborne disease, poor stands and seed pods that are close to the soil because of shortened internodes, or the distance between two nodes,” Christmas said.
The warm germination test of soybean seed this year – used to determine the seed’s potential to develop a stand – is averaging in the range of 85 percent to 87 percent prior to cleaning.
Checking germination and the number of seeds per pound before calibrating drills and planters can prevent overplanting and save farmers money, Christmas said.
As spring approaches, farmers also can start thinking about using soybean inoculants or nitrogen-fixing bacteria to improve yields.
In the past seven years, new inoculants used to increase the roots’ rhizobium population have been tested in Indiana on higher yielding soybeans.
Average soybean yields increased more than a bushel an acre over the test period, Christmas said.
“Using the new inoculants costs approximately $2.50 to $3 per acre and would result in a profitable production practice,” he said.