The News Agency of Nigeria (NAN) reports that the killing is the latest in a string of attacks in the violence-wracked North-east, where more than 20,000 people have been killed in nine years of insurgency.
The killing occurred on Sunday, while the farmers worked on their farms in the plantation, a witness, Jiddah Ahmad, told a NAN correspondent in Jere town, near Maiduguri on Monday.
Mr. Ahmad said the insurgents abducted seven farmers as they worked on their farms and slaughtered six of them in a nearby bush.