In Karimganj district, fields are remained mostly vacant during Sali rice fallow condition. However, only in few areas are cultivated with Blackgram with local variety. KVK, Karimganj has done extensive and adequate field survey and selected suitable areas for Blackgram cultivation under Cluster Front Line Demonstration (CFLD) Programme during Kharif season of 2019-20. A cluster frontline demonstration was taken up with Blackgram variety PU-31. The demonstration was taken up at famer’s field of Shamakul Roy of Brajendranagar village of Karimganj district of Southern Assam. The success point was barren areas converted into Blackgram grown area after Sali rice cultivation. The field data on demonstration of PU-31 and farmers’ local variety were recorded. The yield data of PU-31 was recoded as 7.2 q/ha with potential yield of 12.0 q/ha whereas farmers’ variety were recorded as 5.5q/ha. The district yield average was documented as 5.0 q/ha whereas state yield average was 6.0q/ha.