So I have this large pile of rotting pine needles and was wondering what to do with them. Any suggestions?
I have a LOT of experience composting pine needles, the bottom line is this.
If there are the "waxy" kind?
they are indeed acidic, not to mention it takes a LONG time to break them down.
If they are redwood needles then they are good to use rather quickly, about the same as leaves.
the composting procedure, depending on the other inputs can easily counter any acidity though, just the waxy needles take like 12 months or so to breakdown.
--edit--
you did mention that they are already rotting, if so you could use them already, but the caveat being is ONLY if they are WELL rotten, in my mind that means that you can't visually discern what it is.