>> I added enough compost so that the end result was close to 60-65% adobe and 35-40% compost. 4 times a year on average, we add 8-10" of compost followed by several inches of mulch on top and, each time, it collapses down to less than an inch within 2 months (if it is warm outside).
Yeah, that's what I'm talking about. Nasty stuff! Amazing that it is digested so fast despite the fact that it must be getting low in oxygen as it slumps down.
Sort of like a souffle that collapses if an ant stomps on the kitchen floor.
I found that adding even 10-15% coarse sand and crushed stone plus 20% shredded bark made the resulting pudding a little more "stand-up". Does anyone in your area have sandy or gritty sub-soil?
But I still had to "fluff it back up" every year or two, until some cumulative effect kicked in and moderate amounts of compost and bark maintained SOME slight amount of soil structure. It was as if residual roots were acting as a scaffold to support the pudding from flowing back into the pores I had created the year before.
Perhaps I should use the term "fluffing up" rather than "deep tilling". I use a long-bladed "sharpshooter" or trenching spade, plus a garden fork. I never deep-turn unless I have at least several inches of compost to turn under.
I would kill for 10" of compost and mulch, even ONE time per year!
It feels more like "whipping air into egg batter" than "beating the soil down with a roto-tiller".
I realize that my soil recipe is about the same as that for adobe mud bricks. I guess that part of the brick-making process is to squeeze air out and encouraging the ingredients to stick to each other with few pores.
My process is more like forcing as much air INTO the mix as possible, then firming it down gently, then watering very gently the first few times to try to "lock in" as much open space as possible.
Some of my deterioration is probably just "slumping" in addition to the oxidation of the compost. Getting more bark fibers into the recipe seemed to help.
It was very conspicuous that clay-plus-some-finished-compost would slump back into pudding very quickly, especially if at all damp. However,
clay-plus-some-finished-compost [/b]PLUS sand plus bark plus grit[/b] would not slump as much, as if the bark and grit made a framework like rebar, and the sand "dusted" clay balls so they didn't stick, and the sand "broke up" adhesion inside clay balls so they were friable with a rake and 1/4" screen.
Or I'm imagining the mechanism. All I rally know is that I kept changing my process and recipe until it started working better. But I would love to try again with 5 to 20 times as much compost as I've ever had at one time!
