関連ワード:  what is average corn yield per acre    what is average corn yield    what is average corn yield in iowa    what is average maize yield per hectare    what is the average corn yield per acre in iowa    what is the average corn yield per acre in illinois    what is the average corn yield in illinois    what is the average corn yield per acre in ontario    what is the average corn yield in the us    what is the average corn yield in nebraska