When are you starting this series? Today is April 30, Walpurgisnacht (Walpurga's Night; anybody familiar with the ballet "Giselle"?). Tomorrow is Beltaine (May Day). Auspicious for new undertakings and adventures. So...
(statement of primary theme, forte) Get the cardboard together. Heck, go wild: get two layers' worth of it together!
Find out how many of the other garden members make compost. Surely *some* of them do. Ask the ones who make compost to bring a 3-gallon bucket of it in the interest of an experiment. If they're enthusiastic about the experiment, ask gently (leise, piano) whether they'll contribute 5 gallons' worth.
You, of course, will contribute as much in the way of vermicompost as possible; it's pretty powerful stuff, as we all know, and you've told us on the forum that your specific system generates good volume as well. So that will be your volume contribution.
My idea is that the mugwort patch can be cardboard stifled 100% with the two layers of FREE cardboard. Then one-half of the area will have compost applied on top of the cardboard; the other one-half will "just" have the double layers of cardboard. Why? Because...this is an experiment. (In precisely what, I'm not sure; there are many possible parameters to observe.)
I'm sure you and the other gardeners can decide on two plants which generate edible food + biomass and can be planted on both halves of the mugwort experimental patch. Does corn grow there? Sweet potatoes? I'm thinking maybe vining plants (winter squash, melons) will generate food + biomass; I know sunflowers do.
So that you end up with four areas planted in the mugwort patch:
+ two food/biomass crops
Cardboard + (vermi)compost
+ two food/biomass crops
I would've suggested fava beans, but you said that cover crops were a rough slog, so maybe food + biomass will work for this tough crowd!
Now, what to observe? Hmmm...so many choices! You know best what they'll go for, so here are some ideas:
--Which seeds germinate when? (Maybe give the seeds on the "cardboard only" side a little handful of soil apiece so they don't simply blow away.)
--First edible food?
--Total pounds of edible food?
--Total pounds of biomass **for the community garden's new compost project**? (so that you aren't stuck with the leaf-only stuff)
If the ground to be covered with compost is reduced by half in this way, maybe there will be enough compost, what with the others' and your vermicompost, to give the compost-covered side a real boost. In any case, it may get people interested in contributing biomass from other plants on other plots to a community compost project.
(2nd iteration of the theme, mezzo forte) This is also a good entry point for discussing plant diseases: diseased plant remains should not be composted; they should be trashed so as to avoid spreading the disease to the whole place. No sprays, etc. Just good, old-fashioned hygiene! If you're a good enough teacher, the others will be convinced they thought it up themselves....
If not, maybe it can be the next (or "a future") session.
(harmonic suggestion Windrows
are used in commercial compost production b/c they coordinate with the machines used for aerating and turning the materials. The windrows I've seen were maybe 20 feet wide at the base, tapering to a point approx. 15 feet off the ground, and as long as the compost yard's property, minus a turnaround at either end. The cross-section of a windrow, taken as the viewer looks from one end toward the other, is an acute isosceles triangle which appears somewhat "squashed" on top. Windrows do generate lots of heat
due to the volume of materials; one municipal compost yard in the Bay Area caught fire two or three years ago when the crew made an error, either in the watering or aerating schedule--I forget now which one it was.)
organum, organic ... vox/vita humana