I hate projecting like this since you can never predict how history will unfold but since you people love it il do it.
Farms get colectivised, Oposing owners or farmers get shot or gulaged (this is less of a problem today since agriculture take way less manpower than it used to).
Farmers who don't rebel get their lives and communities improved however possible via schools worker rights or other imediate needs, this is especialy important in the third world.
Production proceeds as normal except distribution is based on need not on buyers probably using established suply chains. (planing can be centralized or not)
Yes farmers are essentially working with guns to their heads, but their lives should be the same if not improved.
By now communist ideology is widespread, so people are well aware of the importance of work and how humans are interdependent, farming is a job like any other and people may be paid with labour vouchers instead of money.
By now we can expect automation to make rural labor even less common than it already is (automation should be one of the main focuses of any self respecting socialist movement)
Communist mindset is the norm, people work because that is and has always been the human condittion, automation should be widespread to the point where work takes a way smaller chunk of someone's day than today.
Money is no longer needed, people just take what they need and want.
Farming probably takes almost no workers and those who work at it are probably biologists and engineers also studying and perfecting production.
