An experiment was conducted to study the estimate of total biomass (shedded leaves plus roots) during bast fibre crop (jute, kenaf and mesta) cultivation and the performance of biomass in soil fertility. The newly released four varieties of Bangladesh Jute Research Institute were used in the trial viz. Deshi jute BJC-83, Tossa jute OM-1, kenaf HC-95 and mesta HS-24. Each of the new variety produces good amount of biomass and enriches the soil fertility. The highest biomass produced with HC-95 (7.30 t ha-1) and lowest BJC-83 (5.23 t ha-1). Appreciable performance recorded with each of the variety in enriching the soil fertility on post harvest soil. Highest organic carbon (1.31%) nitrogen (0.13%) phosphorus (18 ppm) and potassium (0.183 meq/100) were found with the variety HC-95. The percent increment of organic carbon (OC), nitrogen (N), phosphorus (P) and potassium (K) by the HC-95 were 87.14, 150.00, 63.64 and 30.71 respectively over the initial soil nutrient content. According to the performance of the production of biomass and soil enrichment the varieties were in the order of HC-95> HS-24> OM-1> BJC-83.