These little worm workhorses turn compost into rich humus. (Mary Lowther photo)

These little worm workhorses turn compost into rich humus. (Mary Lowther photo)

Mary Lowther column: Contemplating the compost heap

David made me a three-bin compost system

By Mary Lowther

“Why is an old metal tire rim sitting in your mom’s back yard?” I asked David.

“She’s composting it,” he replied. “She says it’ll break down completely eventually.”

I don’t know where she learned to do this, but it makes sense, because the rusting metal would add iron and whatever other minerals they used to make the steel into the soil, adding a je ne sais quoi to the mix.

Given the enormous loss of minerals we flush down the loo, we should try to replenish the soil with more if we want nutrient dense, tasty crops, though I’m not sure how plant-friendly the minerals from mom’s tire rim would be. Some of these minerals can be incorporated into a fertilizer mix, but rock phosphate takes about a year to become bioavailable to plants, so if we add some to our compost heap along with clay, a nitrogen like seed meal or manure and garden refuse, red worms come out of hiding, turning all of this into rich humus that remains stable for decades.

David made me a three-bin compost system: one bin contains compost that will be ready next spring, one holds leftover vegetable scraps that I’ve tossed in over the past year and the third bin is empty, awaiting this year’s additions. As I build the heap in the empty bin this fall, I’ll incorporate the leftover vegetable scrap pile into the mix. I’ve still got bags of leaves from last fall so I’ll use them in the new heap. I don’t shred the leaves. First of all, I don’t have a shredding lawn mower and secondly, I’ve tried using a weed whacker in a garbage can of leaves and never got anywhere because the leaves flew out of the can as soon as the whacker started whacking. Besides, when I layer the leaves along with other amendments in the compost heap, they break down just fine.

I follow Solomon’s guide: I have a bucket of clay, a bucket of alfalfa seed meal or manure, a bucket of soft rock phosphate, the pile of leftover vegetable scraps plus this season’s detritus, the bags of leaves and a garden hose with a valve I screwed on that will allow me to turn the water on and off at the heap. First I put down two layers of thick stalks like corn stalks, the second layer criss crossing the first. This gets everything off the ground and allows a certain amount of air circulation. Then I fork in a three inch layer of vegetable detritus, cover this with a sprinkling of clay, some alfalfa meal or manure, a cup of soft rock phosphate and a two inch layer of leaves. I spray this down with some water — not too much, just enough to wet the layers lightly. I continue adding these layers until I run out. Finally I close the lid down and leave the whole shebang alone, ready to use it in a year and a half in the spring.

In the spring following this winter, I’ll use the compost that’s been sitting in the bin from last fall. It should be mostly composted and stable and won’t pull nitrogen from the soil when I add it to the beds.

Please contact mary_lowther@yahoo.ca with questions and suggestions since I need all the help I can get.

Columngardening