How long between price drops on vacant land? How to market?

[William Dubin]

I have listed for sale a 4 acre parcel that is adjacent to existing single family residential developments, most of the area homes are valued between $350k and $550k, with several at $700k+ and on acre to 1.25 acre lots.

Is listing my parcel with a residential real estate agent participating in MLS the best approach for marketing and selling? It seems there would be other avenues or methods I'm missing.

Next, since vacant land seems to take a long time to sell, how long between price reductions is suggested?  

The county has my parcel's value assessed at $102,000 and my initial listing price was $124,900 and after a month I reduced the price to $114,900.

Thank you and let me know what additional information I can share that would be helpful.