Iowa Code § 210.6
The unit or standard measure of capacity for substances not liquids from which all other measures of such substances shall be derived and ascertained shall be the standard half-bushel secured in accordance with the provisions of section 210.1. The peck, half-peck, quarter-peck, quart, pint, and half-pint measures for measuring commodities which are not liquids, shall be derived from the half-bushel by successively dividing the cubic inch capacity of that measure by two.
[C73, §2046, 2047; C97, §3014; S13, §3009-f; C24, 27, 31, 35, 39, §3232; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §210.6]