Roots are an important component controlling grassland sustainability. They can act as a C sink of atmospheric CO 2 and supply essential nutrients for plant growth. Pasture management strategies intended to increase forage and animal production can also affect root biomass, root composition, and root decomposition. This 2-yr study evaluated the effects of N fertilization and stocking rate (SR) on root decomposition and root chemical composition of grazed elephantgrass (Pennisetum purpureum Schum. '381') pastures. Treatments consisted of a factorial combination of three SR (2.0, 3.9, and 5.8 animal unit [AU] ha –1 , 1 AU = 450 kg body weight) and three N levels (0, 150, and 300 kg N ha –1 yr –1). Greater turnover rates were observed in Year 2 (k = 0.00215 g g –1 d –1) than Year 1 (k = 0.00178 g g –1 d –1). Increasing SR increased root decomposition linearly (P = 0.05) at 0 kg N ha –1 ; nevertheless, when N was applied at 300 kg N ha –1 , root decomposition decreased (P = 0.003). Nitrogen fertilization reduced root C to N ratio and increased root N and root acid detergent insoluble nitrogen (ADIN) concentrations in Year 1, but no effects were observed in Year 2. Root N disappearance followed a negative single exponential model and increased with increasing levels of N fertilization. Pasture management practices such as fertilization and grazing management can alter the root quality and turnover; thus, development of strategies to manage belowground decomposition is a key to long-term grassland sustainability.