Do you ever sit down and ask your son to just dream - if he could do anything, money being no object, what would he love to do?  If that answer does not include any part of farming, then he probably really does not want to farm.  If he has the "want to", then all the other issues can be worked thru.  But there is not point in pushing him if he does not have the "want to".

Same would go for the younger siblings as well.