Composition scheme

Yes he can

Aggregate turnover” means the aggregate value of all taxable supplies(excluding the value of inward supplies on which tax is payable by a person on reverse charge basis), exempt supplies, exports of goods or services or both and inter-state supplies of persons having the same Permanent Account Number, to be computed on an all-India basis but excludes Central tax, State tax, Union territory tax, Integrated tax and cess

Yes you can obtain Registration under Composition scheme because agriculture goods are Exempted (Nil Rated) under GST (Refer Notification 12/2017 CT r).

note : The Composition dealer is not allowed supply Non GST Goods