and the sole income is rent
That makes it a passive activity. All compensation received by you in any form from your tenant is rental income. For example, if you have an agreement for monetary compensation on a regular basis (month rent paid to you with money) and that agreement includes a percentage of the production, then the FMV of that production given to you as compensation is also passive income and it's FMV is included in the total rents paid.
So if the renter is growing potatoes and as part of the rental agreement provides you with say, 5% of the salable harvest, if the tenant could have sold that 5% for say, $1000 on the open market, then you have to add that value to the total of all rents received.
Please note that you will still report this on SCH F, and not on SCH E.
