Two things come to mind.
From my reading, my understanding is that Jean Pain used a large percentage of herbaceous material rather than large heavier woody debris in order to generate good breakdown. In addition to the herbaceous volume, he used a home made shredder that created very fine material that was more like a bent up match stick than the wood chips that are commonly found as the majority product from power line trimmings. The differences are found in the much higher nitrogen per
carbon ratio from the herbaceous material and also the amount of surface area per volume as a ratio in the individual units in the compost pile. The larger the surface area per volume of any individual chip/shred, the more the water can penetrate it, and the more air can come into contact with it, and thus the more biology that can involve itself with it.
Jean Pain's system was a massive
project that had years of trials before he got it down to a smooth science. His piles were not super aerobic, as they were too large/massive, and were not given piped air, and were not turned--for two years! They did, however have an aerobic factor. As far as I can tell the aerobic action in his piles was caused by the structure of the individual matchstick units, allowing air space, and him making the pile damp (not wet) upon building it, thus providing enough air space to get the system rocking. Off gassing from the active bacterial breakdown will open up air channels.
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