Carbon (C) amendments can enhance crop productivity, particularly in semiarid regions. Understanding the potential interference of C amendment with herbicide efficacies is essential to informing the practice. An experiment was conducted in western Nebraska in 2016-2018 to evaluate the effects of coal combustion residue (CCR) and herbicides on crop yields and weed density in the dry bean (Phaseolus vulgaris L.)-maize(db) (maize [Zea mays L.] following dry bean)-sugarbeet (Beta vulgaris L.)-maize(sb) (maize following sugarbeet) rotation. All crop phases of the rotation were present each year and received CCR at varying rates (0, 3.3, 6.6, 13.1, and 19.7 Mg C ha(-1)) in spring 2016. Overall, CCR did not have consistent beneficial effects on crop yields. There were trends for yield benefits with CCR application compared to no-CCR plots in dry bean (p = 0.066) and sugar beet (p = 0.155) in 2017 and maize(db) in 2018 (p = 0.222). In 2016, among no-herbicide treatments, the treatment with the highest CCR rate had a greater maize(sb) yield (16.2 +/- 0.1 Mg ha(-1)) than the rest of the CCR treatments, including the control. The CCR application did not adversely affect herbicide efficacy in weed control. However, in 2016, among plots where herbicide (saflufenacil + dimethenamid-p) was applied, the CCR treatment (6.6 Mg C ha(-1)) had lower maize(sb) yield than the control. Future research should consider factors such as application rates, methods, and timing to assess the potential adverse effects of C amendments on herbicide efficacies.