Calculated belowground buried root bag decomposition rates may be impacted by soil disturbance and that mesh bags can exclude potential degraders. This paper explicitly compares the sequential soil sampling method to the buried root bag approach to determine if biomass degradation estimates over a season differ. The research was conducted at two eastern South Dakota grassland sites (loamy and thin upland ecological sites) in 2011 and 2012 in an area where the grassland vegetation was killed to prevent new root growth. In the sequential core technique, a composite sample consisting of three 4-cm diameter soil cores from the 0- to 15- and 15- to 30-cm depth were collected monthly from May to October, whereas five residue bags were placed 7 cm below the soil surface in spring and removed at the last soil sampling date. The sequential core (61% ± 7.2) and residue bag (58% ± 7.2) techniques had similar root decomposition amounts; however, the sequential core technique had a lower labor requirement than the residue bag technique when the increased sampling requirement was considered.