I have looked around and have not found much good information about exactly what goes on with 'nitrogen deficit' when you add wood to a soil system. Most of the science appear to be focussed on just tilling in
carbon material, not creating strategic pockets of carbon. Here are my working hypotheses:
1. the bacterial robing of nitrogen from the soil solution happens at the surface of wood, and eventually the surface is so encrusted with bacterial-based communities that they no longer actively drain nitrogen. So there is a initial period of intensive nitrogen drain near the surface of a wood particle, but the effect lessens over time.
2. The interior of wood particles is consumed by fungi. The fungi can operate with lower N levels and it is really unclear what the fungi are doing with N in relation to their wood eating habits.
3. plant
roots forage, and so the more heterogeneous the soil the more likely plants will find a nitrogen rich site. Roots can forage for water one place, and nutrients another place, but need water to get nutrients.
4. Nitrogen 'stolen' to begin surface decomposition of carbon rich material is released later as bacterial bodies decompose or are eaten by nematodes and protozoans, so the problem becomes the solution with time.
I met a guy who would pound alder stakes into the ground to improve soil structure--vertical fractures, no digging, patchy introduction of carbon, lots of depth for air and water penetration.
Lots of talk on this issue. Not a lot of science.