As a non-resident of Illinois, you will need to file an IL state tax return to report your IL source income. Please see following link on IL filing requirements. The question addresses a nonresident student but the rules will be the same for any non-resident with IL source income. You will continue to file an IL return as long as you have the farm income.
https://www2.illinois.gov/rev/questionsandanswers/pages/709.aspx
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