Why did Farmers couldn't adjust to Jainism?
Jainism's major tenet is non-violence or Ahimsa, which means not to harm or kill anybody. Mahavira believed that everyone on this Earth (whether it be an insect or a human being) has equal rights to live. Jains didn't eat meat neither were allowed to kill animals for their benefits. But Farmers were tend to use fertilizers/pesticides and other things to kill pests (which was probably not allowed for Jains). If farmers didn't kill them , they would face less loss and their crops would destroy. So Jainism was mostly popular between traders then, and not between Farmers. This is the reason why farmers couldn't easily adjust to Jainism.
I hope that this helps you! Have a lovely day. :)