I'm looking into bioavailability mechanisms in soil. A lot has been done to understand P availability but what has been done to estimate the bioavailable pools of other nutrients?
I'm certain there are plenty for the other elements, but for N, which is more my field, you have Schimel & Bennett (2005, Ecology), Nasholm et al (2009, New Phyt), and more recently Warren (2014, Plant & Soil), which all cover N, some more with a focus on the realisation that it's far more than just mineral N that's bioavailable. That should be a start I think.
Try papers discuss nutrient cycle, they often include soil contribution. my major field is water but during my MSc study i came across couple of references you might find interesting:
If You are interested in boreal forest, here is a good paper about availability of N and N transformations:
Smolander A, Kanerva S, Adamczyk B, Kitunen V (2012) Nitrogen transformations in boreal forest soils - Does composition of plant secondary compounds give any explanations? Plant and Soil. 350, 1-26