A tractor pulls a planter across the field

(Photo: Joseph L. Murphy/Iowa Soybean Association)

Soybean seeding rate and planting date studies

March 8, 2021 | Scott Nelson

The answers to two evergreen questions farmers face each year: “Where to plant it?” and “How thick to plant it?” can matter a great deal to profitability, so Iowa Soybean Association Senior Field Services Program Manager Scott Nelson outlines recent ISA studies to offer some recommendations.

The first ISA study, conducted on 12 locations across three years, tackling “How thick to plant it?” sought to determine the partial returns for various soybean seeding rates so that farmers can seed at the optimal rate and make the most money for their investment. Looking at the data set as well as some separate individual trials, Nelson says the research recommendation for soybean seeding rates are between 130,000 and 140,000 seeds per acre.

“That gives you enough plants so if you have a hail event or If you have crusting or herbicide injury you’ll have enough plants to be able to optimize yield,” Nelson says. “We recommend you shoot for a target stand of 100,000 to 120,000 plants per acre. Now as seed costs increase, returns for lower seeding rates do increase. In those cases when planting with a high level seed treatment you can optimize your profitability by lowering your seeding rates but we would recommend that you do that with a planter.”

The Senior Field Services Program Manager encouraged those interested in helping to provide more data – especially on soybean seeding rates below 100,000 per acre – to reach out.

To hear more about the studies as well as Nelson’s findings regarding planting dates to determine the value of late soybeans planted early, watch the video below.


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