Hah! timely post! this feels like deja vu as i just had this convo in an email 5 minutes ago~
i'm planning to do almost the exact same thing in 5 new beds this season(4'x30'ish each)
i produce Lots of sawdust and in my artisan studio/woodshop/garage. also nice shavings from the lathes and hand-planes that make for great worm bedding and mulch..,
i try to use every last bit of wood ,any cutoffs that get too small become compost or
kindling in winter(maybe 2% is scraps) it's all untreated as i only use wood i personally mill from residential tree-removals.
i had the same concern with nitrogen pulling. i also worry that just burying pure sawdust at the bottom will compress it down and it'll just stay in stasis and not really decay to quick.
so the plan is to layer "stuff". some combo of dust,shavings,compost,manure,green clippings,paper,soil,etc.... and soaking it all good .
inlikeflint, i hear you on the vining woes. i'm just getting over some Nasty poison ivy.the oil is on soemthing from over a year ago,i just cant figure out what.god i hate that stuff..
i've also been at war with ivy for over a decade. last year i found a solution..a big rototiller pulls it all right out as it wraps around the tines.go until it's "full" .then saw/prune off and repeat.if it's an area you dont mind tilling up this is working great for me..hard to reach areas and around plants/trees are still a problem... also it doesnt shred well,super long fibers,wonder if you could spin it into clothing/textile as is done with
nettles etc ?