if you don't till in the sawdust and leave it on the surface to break down, it won't tie up nitrogen. i like to lay down some comfrey leaves , then cover with more wood chips. fertilizes nicely all season.
William Schlegel wrote:Just adding a bit to that sawdust thought. I've found that fava beans grow well for me in sawdust. So a simple cycle of adding a really concentrated carbon source could be adding sawdust then doing a fava bean rotation. Maybe two or more fava bean rotations. The favas fix their own nitrogen so don't seem bothered in the least by the sawdust tying up nitrogen as it decomposes.