buickanddeere
Super Member
Tractors under 75 hp do not requre DEF.
Under 25hp there's no emissions requirements. Between 25 and 75hp there's an emissions limit but it is not as stringent as 75hp+. It can be met with a DPF or DOC in most cases. A few like Mahindra use neither.
No emissions under 25HP ?Emission Standards: USA: Nonroad Diesel Engines