There is a chapter in a the book 'Lita' on the Jewishgen website, that covers Jewish agriculture in Lithuania, including Suwalki. It is at:
https://www.jewishgen.org/yizkor/lita/lit0997.html

The chapter doesn't go into what sort of education a farm manager would have at the time, though I would think they would need to be able to read/write in either Polish or Russian. Do you know from census records what sort of education your great grandfather said he had, or what language he spoke? If he lived up to 1940, that US census asked people how many years of education they had, and what sort of school they attended.

I have two great grandparents who were dairy farmers in northern Lithuania, near Zagare. They would have held leases from local landowners; I think they would have been what we now call tenant farmers. One seems to have married into a dairy farming family, while the other seems to have been born into such a family. I don't think they had anything beyond a cheder education.
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Michele Lock

Lak/Lok/Liak/Lock and Kalon/Kolon in Zagare/Joniskis/Gruzdziai, Lithuania
Lak/Lok/Liak/Lock in Plunge/Telsiai in Lithuania
Rabinowitz in Papile, Lithuania and Riga, Latvia
Trisinsky/Trushinsky/Sturisky and Leybman in Dotnuva, Lithuania
Olitsky in Alytus, Suwalki, Poland/Lithuania
Gutman/Goodman in Czestochowa, Poland
Lavine/Lev/Lew in Trenton, New Jersey and Lida/Vilna gub., Belarus