there was a long multi-page thread on this a few months ago. The law says that kids under a certain age will be prohibited from working on factory farms. Kids working for their families are automatically exempt. Kids working on small farms will also likely be exempt, because the farm will need to meet certain requirements. Also, since most kids who work on farms aren't paid employees, receiving W2s or 1099s, they would be exempt anyway.
99.9% of the children working in the farming community will be completely unaffected.