Check local regs first — some places ban burial. Choose a spot away from wells/water and property lines. Dig deep: at least 1–1.2 m (3–4 ft); for a 75 kg bird 1.5 m (5 ft) is safer. Place the carcass (wrap in burlap/biodegradable bag or put on a pallet), cover with soil and mound ~30 cm to stop scavengers. Wear gloves, disinfect tools, wash hands. For such a large animal consider vet, rendering or cremation services.