Mankato (KMKO)-A Mapleton man faces a possible 20 years in prison after being charged with possession of methamphetamine.  26-year-old Nathan Paul Schull was arrested early yesterday morning after a Blue Earth County Sheriff's deputy found 9.6 grams of methamphetamine in his pocket.  Schull made his first appearance yesterday in Blue Earth County Court and faces on felony count of third degree possession of three grams or more of methamphetamine.  He's being held without bail until his next court appearance.