Purdue University Extension agronomist Shaun Casteel is convinced that Indiana farmers are planting considerably more soybean seeds per acre than they need to in most situations. He has set up a full-blown trial at the Throckmorton Research Center near Romney in Tippecanoe County to attempt to prove that lower stands will still yield as well as thicker stands.
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Very high insurance amounts were built into soybean seeding rate recommendations through the years because planting technology and field preparation equipment didn't used to be as effective. Most university charts assume 90% germination and 90% emergence. Basically, that means you're only counting on 80% of the seed you plant actually producing stems.
With modern equipment, especially with the switch to split-row planters over drills in many but the steepest areas, it's usually easy to do much better that that, assuming that soils are in decent shape when you plant.
One of the companies that has actually dropped seed recommendations is Beck's Hybrids, Atlanta, Ind. They began pushing 130,000 seeds per acre several years ago.
Casteel believes that 130,000 seeds per acre is reasonable in many situations. What he really deals in is plants per acre. He's looking for a minimum of 100,.000 plants per acre when all things are accounted for, and the crop emerges.
"You've got to have a uniform stand and good weed control," says Bill Cobbler, Stewart Seeds, Greensburg, Ind. He's head of sales for the ASI company. ASI is owned by Monsanto. Since you won't get
Stewart Seeds has customers dropping as few as 120,000 to 140,000 seeds per acre. They have reduced their seeding rate recommendations that they pass on to customers, compared to what they were in years past.
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The exception will come as planting gets delayed into June, Cobbler notes. This may be a year where that exception becomes important. The closer to June 15 that the calendar moves, the more seed he believes you may want to apply. It has to do with encouraging soybeans to get tall enough so they can perform well.
How much you up the seeding rate may be your preference. As the calendar moves deeper even than June 15, say to June 25, you may want to increase the seed drop even more. Cobbler suggests it would be reasonable to increase the seeding rate 15 to 25% if you are still planting soybeans June 25.
However, that's based on their original rates, which may be less than what you are used to planting in the first place. As it gets later and you're still planting soybeans, consult your own seedsman to see what rate he or she recommends that you should be planting in that particular situation.
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