I'll reference a report that Meyers Norris Penny did for Fertilizer Canada. The report is titled, “Implications of a Total Emissions Reduction Target on Fertilizer”.
This is based on a 20% and not a 30% reduction. Yields, of course, will go down through time as soil reserves of nutrients get depleted. If the implementation were to start in 2023 out to 2030, Myers Norris Penny predicts a loss of 23.6 bushels an acre of canola, 67.9 bushels an acre of corn and 36.16 bushels of wheat per acre. That would all essentially be loss that would have to be made up elsewhere.