Basis levels rose by $2 per ton in the Iowa cities of Cedar Rapids, Iowa Falls and Sioux City, though offers held steady in Council Bluffs.
The Iowa moves higher continue a trend that has seen other Midwest processors raise their basis levels this week.
The supplies were tightening due to seasonal maintenance project at processors. Plants typically shut down ahead of the harvest, limiting the amount of soymeal available for sale.
Spot market deals were light as most end users were waiting for the harvest to begin. Basis offers were expected to ease once the processors start accepting deliveries of newly harvested soybeans from processors.
End users were inquiring about new-crop contracts, but most dealers were reluctant to commit to new deals until they have some idea about the quality of the new-crop supplies, a mid-South broker said.
At 9:02 a.m. CDT (1402 GMT), Chicago Board of Trade September soymeal futures were down $1.60 at $335.10 a ton.