Good luck. What fiber? I see a lot of those type of stains up here. It's what make mustard yellow. And wAs only used to appeal to kids.
I see it around my clients area of worship.
As Larry says, the UV light is important part of the process. We have had success with StainZONE and the uV light. You will get best results if the carpet is not too badly abraded and if it has been protected in the last year. It will take a lot of patience to remove turmeric from old worn carpet.