Official US agricultural policy and habitual farming practice have made growing maize together with beans and/or squash, tomatoes, and peppers nearly impossible to do competitively. That could be fixed with policy changes that would be fought by the biggest agribusinesses.

Corn is among the most efficient natural converters of sunlight into chemical energy useful to the plant (with some left over for the farmer), but photovoltaics beat it by up to 10x. Capturing CO2 and producing glucose, starch, ethanol, and kerosene by an organic chemical process could be much more productive, by any measure, than via corn, which must anyway also grow stalk and leaves. The power could come from solar panels sharing fields with vegetable crops (e.g. tomatoes and peppers) that benefit from the shade they would provide by multiplying yield, and with wind turbines which take up very little ground footprint.

Combining solar, wind, farming, and chemical processes yields much better results than keeping them separate.