You sold the futures contract correctly. The only problem is that you think you want to sell corn, and you are afraid that the price will fall or you will be short. This is not right. As long as you hold the spot in your hand, it is equivalent to holding more than one order in your hand.
The current spot price is 100, and the due spot price is 1 10, so your spot profit is 10. The spot price of futures is 105. At maturity, the spot price of futures tends to be basically the same. The price is 1 10, and you lose 5.
I hope I made myself clear.