Maize agriculture essentially fed Iowa in abundance (10)

I believe the answer is:
cornucopia
'abundance' is the definition.
(a cornucopia of something is an abundance of it)
'maize agriculture essentially fed iowa' is the wordplay.
I cannot really see how this works, but
'maize' could be 'corn' (synonyms) and 'corn' is found within the answer.
'iowa' could be 'ia' (abbreviation) and 'ia' is located in the answer.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for cornucopia that I've seen before include "Symbol of plenty" , "There's plenty here!" , "Great abundance" , "mine" , "Horn of plenty" .)
