I am no expert in this...but have tried to follow ERP development. Odoo is well known, but I understand it isn't truly open source and can require specialized knowledge to personalize. Looking more now at ERPNext.

Ideally, we would have an ag version of SAP. There have been a few attempts in the past...all have had fatal flaws. But it is what we all could use. It should be designed and built BY farmers, FOR farmers.