Comment by defrost

Subsistence farming would be farming to only feed the farmers with little excess left for trade, it's a little too keyhole in this context.

They're talking more in the direction of EU scale closed loop / closed cycle agriculture, in which a network of farms across countries interop to exchange resources (pig and chicken waste, for fertilizer, for example) in order to reduce or eliminate outside inputs (synthetic fertilizers from the Gulf, for example), but still work to maximise production for EU consumption.