is there an efficient way to convert gb _trees to json in erlang or maps ?

{46,
                 {{25,56},
                  {fld,{25,56},0},
                  {{25,30},
                   {fld,{25,30},nil},
                   {{25,11},
                    {fld,{25,11},0},

I would like to convert this type of tree into json for transmission to another application