Abstract: A field experiment was carried out to study the effect of different tillage practices on root growth and yield of rice in silt loam soil. The soil was calcareous gray belonging to Sonatala series of Old Brahmaputra flood plain soil. The treatments comprised of no tillage-(To), T1 (CP2), T2 (CP3), T3 (CP4), T4 (PT2), T5 (PT3) and T6 (PT4). The highest root mass density of 2.66 mg cm -3 and the lowest root mass density 0.90 mg cm -3 were found under T6 (PT4) and To (control) respectively. The maximum root mass density (4.22 mg cm -3) was recorded at 0-10 cm depth of soil. The root density drastically reduced at the deeper depth. Tillers number/hill, plant height, panicle length, number of grains/panicle, grain and straw yield at different tillage practices significantly increased over control. The T3 (CP4) gave the highest plant height (95.93 cm) among all treatments. The highest grain yield (5969.25 Kg ha -1) was found under T6 (PT4) whereas the lowest yield (1451.03) was obtained in control treatment. The grain yield shows a highly positive significant relationship (r=0.993) with root mass density.