Do this to keep it fresh for a long time.

Check occasionally, if the ginger is wet, replace the paper, add more baking soda and wipe the ginger.
Preserve ginger with rice
Use paper towels to wipe the ginger clean and dry.
Put ginger in a rice bag and tie it tightly to preserve it. This way, the ginger will not wither or sprout.
Preserve ginger in sand

Prepare some clean, dry sand.
Put the sand in a box and bury the ginger inside.
Leave the box of ginger in a dry, cool place. This way, you can keep ginger fresh for about half a year.