On Monday, September 11th, Governor Kim Reynolds signed a proclamation relating to the weight limits and transportation of grain, fertilizer, and manure.
This proclamation allows vehicles to be overweight (not exceeding 90,000lbs gross weight) without a permit if they are transporting corn, soybeans, straw, silage, soybeans, stover, fertilizer (dry, liquid, and gas) and manure (dry and liquid. This proclamation is effective immediately and continues through October 11th, 2023.
This proclamation applies to loads transported on all highways within Iowa (excluding the interstate system) and those which do not exceed a maximum of 90,000 pounds gross weight, do not exceed the maximum axle weight limit determined under the non-primary highway maximum gross weight table in Iowa Code § 321.463 (6) (a) and (b), by more than 12.5 percent, do not exceed the legal maximum axle weight limit of 20,000 pounds, and comply with posted limits on roads and bridges.
See the proclamation here.