For what purpose? There is simply no way a battery powered tractor can compete at field work. Maybe if moving a couple wagons around is the extent of the task, it might be ok. But for 8-12 hours of pulling a plow, disc, or even a cutter .... no way.
An electric car will typically go 70-100 miles on the freeway on battery only. That's a 15-ish hp load. Imagine what a 40 hp load pulling a plow would do to the batteries!