Box 7 is box 1 and box 3 added together.  You need to look at the grain sales to the cooperative and figure out why the client sales do not match box 3.  Usually is storage and checkoff.

@meoleson  2019 Form 1099-PATR, box 1 is the farmer's current year cash dividend + the allocated deferred non-cash dividend.  The farmer will likely only have the cash portion of the box 1 amount entered into his books.

2019 Form 1099-PATR, box 3 is the total gross grain [livestock] sold through the coop during 2019.  You are correct in that most often the farmer reports only the net grain sales through the coop in his books under grain sold.  The coop deducts items such as the commodity check-off, drying, storage, trucking, service charges, and other fees from the gross grain check.  So, when you gross up the farmer's net grain sales sold through the coop entry in his books to match the amount reported in box 3 of the 1099-PATR you need to also enter said grain check deducts as expenses on the Sch F as well.     

@lizmctax  you do not actually enter 2019 Form 1099-PATR, box 7 into PS19. 

You use the amount entered in box 7 to compute the amount to enter into the Schedule F QBID Smart Worksheet, Continued, line K 1 Net income allocable to qualified payments from agricultural or horticultural coop.....  [scroll down on the Sch F until you find the QBID Smart Worksheet].

You know, use box 7 to figure the percentage of Sch F gross income from coops to compute the amount of Sch F net income attributable from coops that you then enter on the QBID Smart Worksheet referenced above.