Lines 10–23 of "The Farmer" by W. D. Ehrhart mean that the speaker recognizes he has failed as a father and a husband but still goes out into society each day, where he encounters people who will never understand what he went through as a Vietnam War veteran.
Overall, one could argue that "The Farmer" is an allegory on the experiences of a war veteran who finds it difficult to adapt to civilian life—not an uncommon experience among former soldiers.
The speaker of the poem, in line 10, candidly acknowledges his failures as a husband and a father. This is what he means when he says
I have sown my seed on soil
guaranteed by poverty to fail.
And yet despite the difficulties of his home life, the speaker doesn't complain. Instead, he goes out into the world, where he regularly encounters people who do not understand him. That is because they have no direct experience of war and so cannot begin to comprehend what the speaker and other army veterans have been through.
The speaker fought in order to relieve the poverty of the people that he meets, to defend their freedom. And yet they don't truly understand or appreciate his service. Undaunted, the speaker nonetheless goes out into the "fields" every day. That is to say, he goes out into society each day in order to heal his soul, made barren by his traumatic experiences of war.