Shrub willow biomass crops (SWBC) have been developed and promoted for widespread deployment in northeastern and mid-western US as well as in Europe. There are concerns that the production system could reduce the soil organic carbon (SOC) over time due to soil disturbances and repeated three-year harvest cycles. This study assesses changes in SOC beneath shrub willow (Salix x dasyclados SV1) biomass crops utilizing a 0, 5, 12, 14, and 19-year old SWBC fields. The sites' management history was similar, suggesting uniform SOC contents prior to plantation establishment. SOC contents were analyzed by total (i.e. 45 cm) and by layer (i.e. 0–15 cm, 16–30 cm, and 31–45 cm) across different ages. Mean SOC contents to 45 cm depth ranged from 175 to 188 Mg ha−1, and showed no statistically significantly differences across ages (p = 0.15) and no interaction between age and depth (p = 0.19). SOC contents differed significantly with soil depth when averaged across ages (p < 0.0001). Statistical analysis of SOC contents by layer, however, showed that SOC contents in the upper 15 cm depth were significantly different (p < 0.001). Linear contrasts of mean SOC contents for the 0–15 cm depth revealed that the 0-year old was significantly different compared with the 5, 12, 14, and 19-year old SWBC. •Shrub willow biomass crop (SWBC) production system could impact soil organic carbon over time.•We assessed SOC changes in five SWBC chronosequence: 0, 5, 12, 14, and 19-yr old.•Mean SOC contents to 45 cm depth showed no significant changes across the five different ages.•SOC changes occurred in the upper 15 cm depth during the first five years after establishment.•SWBC production system did not result to negative impact on this component of soil resources.