Chooks and Worms in the Greenhouse
Chickens in the Greenhouse
I was intrigued by the idea of keeping chickens in the greenhouse since seeing it in practice at Polyface Farm in the Shenandoah Valley (home of Joel Salatin, sustainable agriculture guru). Part of our Fall, 2005 greenhouse renovation referred to in “Greenhouse Basics” (replacing the foundation boards with block) involved installing some block partitions for chicken pens as well, with light wood framing and poultry wire on top. (Click on the thumbnail above for design and construction details.)
I had three reasons to overwinter chickens in the north end of the greenhouse. Plants take in carbon dioxide in order to harvest energy from its breakdown into carbon and oxygen, so the CO2 in the poultry’s exhalations should be of benefit to them. Now, before you think I’ve gone off my rocker factoring chicken breath into the greenhouse equation, know that in The Netherlands growers pay good Dutch money for bottled CO2 to pump into their greenhouses. Of course, there is no way I can measure how much difference my flock’s exhalations make, but the logic seems sound.
My second assumption is that the body heat of the enclosed flock will moderate the overnight chill in the greenhouse. Again, I have no control for testing this proposition scientifically, but I had 43 chickens, three ducks, and two African geese in there at the height of last winter—I’m convinced that more than 250 pounds of warm living bird has to make a difference.
Finally, I hate confining my flock in the winter. It’s a necessity, since they would degrade the dormant pasture sod if on it full time. (I make do with deep litter over an earth floor as the best alternative inside.)
That is, it was a necessity, until it occurred to me I could heavily mulch the garden area outside the flock’s sleeping quarters in the greenhouse pens, net it with electronet fencing, and release the birds onto it during the day. (I used several 800-lb round bales of old hay, since a dry season did not permit a heavy fall cutting off my pasture.) The results were more than satisfactory: The mulch was deep enough (six to eight inches) to prevent freezing of the soil in my climate (Zone 6b), and the busy chickens stcratched down through it to live animal food (earthworms, slugs and slug eggs, etc.), and germinating seed in the hay—both a terrific boost in nutrition. The mulch absorbed the poops laid down and scratched in by the flock, rather than accumulating as a slick glaze on a patch of bare frozen dirt, eager to run to the nearest stream, lake, or estuary (to say nothing of the groundwater) with the first thaw. The mulch thus recaptured that manure as fertility for the soil in the coming season. The chickens, quite cold hardy if not wet, enjoyed themselves in the sun, on even the coldest days. And shelter at night, or from rain during the day, was always a few steps away inside the greenhouse pens.
By spring, the mulch hay had been shredded to something between fine mulch and finished compost, and was easy to apply in the garden, even between closely planted crops like carrots. (When you use a mulch like this, which contains pulverized droppings, it is advised that you allow 60 days—some would say as much as 120 days—before harvest. Frankly, I have not paid much attention to such “withdrawal times” when using homestead manure—an entirely different beast from manures of animals in high-confinement operations—and have never had the slightest problem with such mulches.) Finally, remember that the mulch was laid down over a garden, and was protective of its soil, preventing the horror of bare soil over winter.
Vermicomposting in the Greenhouse
I experimented with a 3x4-ft worm bin for several years. When I did the greenhouse renovation project, it seemed the perfect opportunity to step up to more serious vermicomposting. We put in two courses of 4-inch hollow block for the bins, dug almost 16 inches into the earth, 40 feet right down the center of the greenhouse. Every 8 feet, we put a cross wall of block, to give five 4x8-ft bins 16 inches deep. We put two 4x4-ft lids made of ¾-inch plywood on 2x4 framing over each bin, giving in effect two 4x4 sections in each bin. (Great for management: I can empty out one section and refill with bedding. The worms migrate in and populate from the full side.) When the flock is out of the greenhouse over the summer, their two 8x8 pens are used for an additional 128 sq ft of vermicomposting bin.