This collection contains supporting information for M. Y. Louge, A. Valance, Nikuradse and Shields: turbulent roughness controls shear stress at incipient sediment transport, J. Geophys. Res. Earth Surface (2024). The Nikuradse (1933) data of Darcy friction for turbulent flow in roughened pipe and shear stress measurements at incipient transport from Shields (1936) and later authors indicate that the threshold dimensionless shear stress Sh for entrainment of cohesionless sediment of diameter d is proportional to the 'turbulent roughness' z0 in the core of the boundary layer on a flat surface, Sh = (2.28+/-0.18) (rho/rhos)^(1/3) z0/d, where rhos and rho are material densities of solid and fluid in the range 2.6 < (rhos/rho) < 1.3 10^6. This expression is valid when the boundary layer is fully turbulent for Reynolds numbers 0.63 < Re* < 1100 based on shear velocity and d. Such insight suggests that turbulent roughness governs the entrainment of particles from a planar sediment bed, whether Newtonian liquid or gas continua are involved. It also provides a new interpretation of the ratio z0/d at incipient transport, not as a geometrical aspect ratio, but rather as friction that the turbulent flow must exert to lift sediment from the surface.