It has an impact, not sure how much, but ISU is definitely an AG industry heavy fanbase, and I know a lot of farmers that will not be going to a game until their crops are out, and that includes their employees and the support facilities workers.
And there are a lot more AG jobs that are working during harvest than just the farm owners. Hired men are working extra hours now, Elevators, Ag Sales, Implement dealers and mechanics, Chemical facilities, Ethanol facilities, Trucking, Railroads, anything that has to do with AG or supporting AG is working extra hours and weekends right now.
A lot of time people look at how many less "farmers" there are today and say there are less Ag workers. Well that family farm that was 500 acres 25 years ago that is now 5000 acres still takes about the same number of workers, and support industry facilities and workers. Just less are the owners and more are employees. Those hired men while not counted as "farmers" in the numbers people see, they are still working extended hours during harvest.