Stratospheric aerosol geoengineering options, involving injection of sulfur dioxide (SO₂) aerosols into the stratosphere, are being proposed to reduce the heating effects of increasing anthropogenic atmospheric carbon dioxide (CO₂). While the impacts of stratospheric aerosol geoengineering on climate changes, such as stratospheric ozone depletion and weakened monsoons, have been extensively investigated in the past few decades, few studies have considered the biogeochemical (BGC) responses and feedbacks on land. Previous Earth system model (ESM) simulations incorporating stratospheric aerosol geoengineering scenarios primarily focused on the atmospheric radiative forcing and temperature response in the absence of ocean and land responses. The land model setup in these simulations did not incorporate the carbon-nitrogen cycles and effects on the hydrological cycle considering vegetation responses. Since ESMs simulated very different aerosol distributions for the G3 and G4 scenarios in the Geoengineering Model Intercomparison Project (GeoMIP), we instead adopted the G4SSA scenario to simulate the BGC responses and feedbacks on land due to stratospheric aerosol geoengineering using the Community Earth System Model with active biogeochemical dynamic variations enabled. Implications for the terrestrial carbon cycle and hydrological responses will be presented.