Unless I'm going senile, I've done this calculation a few times and consistently I get that a solar farm produces 25-50 times more energy a year than corn.
Interesting take though, I'm not saying that growing corn is best way to "produce stored energy", but in your comparison it's almost like direct competition to for PV + batteries of any sort.
Battery storage looks practical to smooth out diurnal variation in power supply and demand but doesn't look so practical to smooth out seasonal variations, some kind of chemical storage could be the way.
Food security is the primary reason for corn overproduction and ethanol is what we do with the excess corn instead of let it rot.
One wonders a bit, you take hydrogen and nitrogen to make ammonia. Then you spray that on a field and grow plants to turn it into protein. What if you skip the plant step and convert the ammonia to amino acids directly.