Urban agriculture soils are commonly amended with compost to improve fertility, yet the functional responses of these systems to biochar additions across application rates remain poorly understood. We conducted a field experiment at Three Sisters Gardens (West Sacramento, CA, USA) to evaluate how biochar applied at 0, 10, 20, and 30 t ha−1 influenced soil physical, chemical, and biological indicators in compost-amended plots under corn and squash production. Late-season soils were analyzed for v