In order to generate added interest and contributions, I would suggest a stickied link on all forum sections ie in formation, foreign languages, general, tips, etc. this link can then redirect the poster to the actual current competition thread. Change of text color and font in order to make it stand out will also help.
Another suggestion would be to create a log on pop up on T11, like the daily Christmas gifts giveaway, so that all managers are informed of new competitions, closing dates, or thread links on a regular basis.