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More on Compost

By Kate Gridley, April 7, 2011 - 10:10am

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While John worked at fixing the raised beds this weekend, and built a tunnel so I could get some plants into the ground earlier, I messed around with compost.

Sounds disgusting -- but actually, while I discovered no rich crumbly soil at the bottom of the heaps, I did find rotted material that was quite dry. I think it needs to compost further. So I reorganized our compost.

I have always been a lazy composter. Which is to say, while I believed in the theory of composting -- that circular miracle where food and plant scraps go back into circulation, with the addition of soil, and maybe some limestone, altered by tiny microbes and worms -- it seems like it has never really happened in my yard.

Every year, we pile as much organic detritus as we can fit into the southwest corner of our lot, behind some scraggly yews. When there's no more room -- which happens quite quickly on account of how much stuff there is to compost (grass clippings, leaves from the maples, garden thinnings, weeds and kitchen waste from four people) -- we start hauling "waste" to our friend Bill's bonfire pile. Last year, we started another pile in the northeast corner, with leaves going into a bin ( we keep them separate, hoping for leaf mold), kitchen scraps going into a covered bin, bigger pieces going into a third. But there has been no perceptible composting action.

The pile behind the yews sits, and sits, and compresses, and sits. Put it this way, whatever is happening is happening so slowly, I assume we've done something wrong.

As I did my research this past weekend, I discovered that I have never really understood what needs to happen. I had heard it might have something to do with temperature. My friend Eileen's barn caught on fire because of heat from a compost pile. But how did it get that hot and do I want a compost pile that starts fires? Where would the heat come from?

The materials -- plant wastes -- that go into compost contain beneficial substances. This is obvious: they were once plants, they successfully grew, incorporating whatever nutrients they needed. Elliot Coleman, in his wonderful book Four Season Harvest, suggests "don't pass up any weeds, shrub trimmings, cow pies, or odd leaves you can find. If you mix together a broad range of plants with different mineral makeups, the resulting compost will cover the nutrient spectrum."

His book is becoming my garden bible. He then suggests dividing the compost into two categories "based on their age and composition. The two categories are called green andbrown." The green ingredients come right out of your kitchen, plus all the fresh green trimmings that come out of your garden and off your lawn. These materials are fresh, and they are moist. The brown ingredients are older and drier and they decompose much more slowly. One example of "brown" is my pile in the corner of the yard. So is the straw lying on the top of my raised beds.

According to Coleman, you need both. So I tore apart all the various compost piles in the corners of my yard this weekend, and started over. I have set up three bins in a more accessible place, and I have started to rebuild them according to his recommendations. The trick is the layering of green and brown materials, with a layer of soil. Start with a brown layer ( 3 inches), then a green layer (1 - 6 inches), then a thin layer of soil (1/4 to 1 inch). Repeat.The moisture content has to be just right. And there has to be oxygen.

It turns out that composting is about fire. Coleman writes "the decomposition process is akin to a smoldering fire. If you take care in building the heap, it will "light" every time. The slow combustion of the compost heap is an exothermic reaction -- that is, it gives off heat. The microorganisms create the heat by breaking down the organic material...The temperature inside an active heap can reach 140 degrees....the brown ingredients provide the fuel. Straw, for instance, is a carbonaceous material with a high ration of carbon to nitrogen. The green ingredients provide the fire... "

If a compost heap is too wet, it will give off a bad smell. If the heap fails to heat up, it is probably too dry. I am thinking that my compost heaps failed to fire up -- too dry -- OR I had the wrong mix of green and brown materials.

My friend Allen (nicknamed The Happy Farmer) was really into composting. He had three compost heaps, each one a circle ten feet in diameter, contained in a chicken wire cage. He had maps of each circle, so he could remember what substances he had put in where - and when!

That's not happening in my yard. No compost maps for me. For now, I am reading madly about composting because I want my heaps to ignite: I want the microbes to be happy, and I want to close the circle between my garden, it's waste products, enriching the soil where my plants grow.

I'll be writing more about composting as the season unfolds. I am beginning to wonder if I need not only a soil thermometer, but a compost thermometer, too.

TAGS: Kate Gridley, Gardening

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