Where does he get the funds to buy the corn from Gavin?
Yes - he uses part capital and part borrowing same as every other business in the land.
Have a look at any company you work for and see that their balance sheet will show working surplus, profits, and extent of borrowing. The level of borrowing will be offset against notional worth, but debt it is no mater how you may try to repackage it, and debt it is at the centre of the capitalist system.
Are you really believing that there is sufficient money to cover the debts across the capitalist world? If so then you are more ignorent than you look.