The Biden administration spelled out guidelines Tuesday for tax breaks designed to boost production of sustainable aviation fuel and help curb fast-growing emissions from commercial airplanes. The Treasury Department actions would clear the way for tax credits for corn-based ethanol if producers follow “climate-smart agriculture practices,” including using certain fertilizers and farming methods. The announcement was praised by the ethanol industry but got a much cooler reaction from environmentalists. To qualify, sustainable aviation fuel, or SAF, must cut greenhouse-gas emissions by at least half compared with conventional jet fuel made from oil. Congress approved the credits — from $1.25 to $1.75 per gallon — as part of Biden’s huge 2022 climate and health care bill. Administration officials said commercial aviation — that is mostly passenger and cargo airlines — accounts for 10% of all fuel consumed by transportation and 2% of U.S. carbon emissions.