Observation: Compost bins "Goldilocks" zone (edge effect)

Here's a recent observation in our community compost bin system which I've been managing for almost two years now.

The deposit bin on the left trends naturally towards "green" deposits.   It has fresh, nitrogen rich materials from frequent kitchen scraps.

The finishing bin on the right has more "brown" leftovers.  There are always bits of wood and paper and materials which are carbon rich and break down more slowly -- until I swap or mix the bins.  I use a newly upgraded wooden box/crate compost sifter to separate the larger bits of browns, and I add them to the left.

But right there in between the bins, in no-man's land...  that spot has always been the most beautiful in texture and tilth.  A little bit of edge-effect is happening between these bins.

So my question of course is why?  

Here's what I think so far:

Local urban nibblers have easy access to the middle there.  Their natural "tillage" and tunneling is accelerating the mechanical decomposition and mixing process.

Additionally, the nibblers may be "inoculating" the center area with more local microbes carried on their fur, claws, or within their bodies.

The center material could just be coming from the best materials from either bin, which are closest to the ground due to leaching.  This material is more balanced and well aged, and is less likely be to oxidized or sterilize in the sun and air.  A hydrostatic pressure of sorts from both bins is slowly pushing material downward, then inward to the middle, and then upward.

The in-between zone is well insulated and protected.  Perhaps temperature or humidity or airflow is more ideal there.

Larger pieces are unable to filter through to the center section.  So only the small, nice stuff gets through.  It is a natural sifting setup and the process could be leveraged in future designs.

Time to mix in several more permaculture principles and a few new observations to this compost bin setup.  

Some principles:

Produce no waste.

Integrate rather than segregate.

Use edges and value the marginal.

Obtain a yield.

With fall comes fall decorations, and that means plenty of carved pumpkins!  For the past two years I've encouraged folks to put them into the compost bin.  After all, pumpkins are nutrient dense and carry a bunch of biomass, so it would be a shame for them to get tossed into a dumpster.  Fast forward, and what have we here?  A volunteer!  The vine right next to the bin grew from the seed of one of those tossed Jack-'o-lanterns.  It's produced two nice pumpkins, one of which is about 12" diameter now!  And recently, I discovered yet another pumpkin nestled between our other two bins (which are not in use).  I've propped it up on a pot to keep it dry and reduce nibbler pressure.  They will make for good fall decoration for the preschool, perhaps.

In addition to the volunteer pumpkins, we have had maybe five pepper plants pop up around the bin.  Are they volunteers, or did I take a bunch of seed a while ago from a discarded pepper that was in the bin, and then spread them everywhere along the side of the bin?  Yes and yes!  One of them has even started producing fruits!  I dug another couple up, and have transplanted them into my new "foundling" fence garden which I intent to share with the community quite soon.  

The strongest pepper is in that "goldilocks" zone I mentioned, as is the pumpkin vine.   I find it interesting that the peppers are doing so well, even though they are on the north side of the bin, and receive a fair amount of shade.    Perhaps there are just so many nutrients available, that the peppers don't mind a little more shade?  The best plant also had a couple black nightshade weeds collocated, which I've cut back.  Perhaps cutting the fellow nightshade plant down rapidly freed up energy for the sibling pepper?  Are these family weeds purely competitors, or are they also "nurse" plants in a chop and drop scenario?  Hmm.


Other thoughts:

Most people think of a compost bin as a distinct element, which of course it can be.  Its primary function is to produce compost after all, and that compost is transported elsewhere to help desirable plants.

But it's equally possible (desirable even) to close or eliminate that gap -- in other words, integrate rather than separate -- the bin and the garden.  After all, the best place to store nutrients is in healthy living things.  Every time it rains, nutrients and life will leach from a compost pile into the surround soil, so we might as well make good use of that surrounding zone and capture that life flow -  a little permaculture design energy flow analysis there for you!

There are other composting systems which better integrate the compost material and the garden...e.g. Ruth Stout method, mound culture, in ground worm bins, garden towers.  But even a normal bin can be integrated.

The yield of a system, even a silly compost bin, is theoretically unlimited.  Here are some of the unexpected yields I've experienced the last two years thanks to this community bin setup.