Side dress with composted manure.
Also a lot of those recommendations are based on the assumption that the only nutrients in the soil are applied fertilizer, and with corn being such a heavy user with a small root system, so side dressing concentrates the nutrients where the plants are. if your field has good fertility and you have applied manure to the entire area, then there will probably be enough nutrients available.
Either way, side dressing with compost i very effective, we do this on several of our crops.
Carl
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