Field experiment was conducted during rainy season (Kharif) 2018 to study the bio-efficacy of pre-emergence herbicides in dry direct-seeded rice. The treatments were weedy check, weed free, pendimethalin applied as pre-emergence at 1.0, 1.5 and 2.0 kg/ha fb post-emergence application of bispyribac-sodium at 0.025 kg/ha with amendment of biochar at 4.0 t/ha and without amendment of biochar. Total weed dry matter accumulation was maximum at 60 DAS. The highest grain yield was obtained in weed free treatment which was 7.38% higher than pendimethalin as pre-emergence at 1.5 kg/ha followed by bispyribac-sodium at 25 g/ha under biochar condition. Recommended dose of pendimethalin (1.0 kg/ha) along with biochar had 7.5% less yield compared to 1.0 kg/ha pendimethalin without biochar amendment. Higher dose of pendimethalin reduced grain, straw and biological yield, setback on yield was more pronounced in non-biochar amended soil. Addition of biochar decreased the B:C compared to without biochar treatments.