Compost shortage

Once my composting operation settled into a routine, I could count on having two of my four bins produce a good supply of fully made compost every year. Every fall I spread a thick layer on the vegetable bed, where organic matter is used up fast by food-producing annual plants. 

Food compost from the closed bin will enrich the soil of the vegetable bed

When I planted new areas, I spread compost on the soil surface before starting to dig. When I learned that harvesting (really mining) peat contributes to global warming by releasing carbon, I started mixing finished compost from the bins with coir (coconut fiber) to make homemade peat-free potting mix.

     This year I haven't produced as much compost as I used to, and I'm going through it faster. Last year I gave away so many potting mix samples that I ran short of finished compost. 

Cute, right?

The reason for the samples was to interest garden club members I met in making their own peat-free mix. I thought if they tried mine, they'd see how easy it is to make a mix that looks, feels and functions a lot like commercial products based on peat. 

     Last year too I piled fewer fall leaves into the bins. I used to heap up leaves on the bins at the end of the gardening season, knowing the fluffy mounds would flatten during the winter, gradually decompose, and become part of the compost. But last year I went big on piling the whole leaves on beds to provide winter shelter for native insects.

Collecting leaves from the sidewalk to pile on garden beds

     Another call on my compost supply last year was the sheet composting project I started last March. The majority of the material for this composting-in-place soil improvement mound came from thick layers of wood chips and fall leaves. Thinner layers of compost were needed, though, to introduce soil organisms that would do the decomposing. I can see that they're doing their work. Already this fall the mound has sunk to about half its original height.

The sheet composting mound is sinking and starting to look like soil

     These extra demands on my compost economy have left the bins nearly exhausted this fall. Cutting down vegetable plants and emptying summer containers, I've started the process again in two of the four bins. According to the old system, though, the other two bins should be full of year-old developing compost. They're not.

The cupboard is bare

     In the past, I've just waited two years for the compost to be finished. Usually I make a point of adding garden waste to the compost as it comes, with no recipe. But I don't want to go through next summer with no finished compost. I may have to adjust my lazy-woman's composting method this year. 

     To get back on track, I can mix shredded leaves with the dead plants in the bins. 

Shredded leaves will decompose faster

Combining "brown" high carbon and "green" high nitrogen components will speed up the process. Desperate times call for desperate measures.

A mother's work is never done

I felt I had a personal encounter this week with the biggest bumblebee I’ve ever seen. Maybe I’m wrong, but I seemed to spot the same rotund, furry bee visiting flowers near the house several times in the course of a sunny afternoon. 

    Perusing Heather Holm’s Pollinators of Native Plants, I learned that the bee I was watching was probably a queen looking for pollen and nectar for her offspring. 

Earth bumblebee (Bombus terrestris)-photo Ivar Leidus

Bumblebee queens can be three times as large as worker bumblebees. The orange ball I saw on one of her back legs was probably her corbicula, or pollen pouch. When I watched her moving from flower to flower, she was collecting pollen grains on her head, thorax and abdomen, combining them with nectar, and storing the mixture in the pouch to carry back to her nest.

The orange ball is her pollen pouch-photo Tony Wills

    Another bee behavior I’d happened to notice also made sense now. A few days before, I saw a bumblebee fly into a small hole in the mound of sheet compost I started last month. The mound is topped with chopped straw and hay over a layer of compost; under that there’s a thick pile of wood chips. Now I know that this could be an appealing spot for a bumblebee queen looking for a place to dig a ground nest. 

The top of the sheet compost offers a good bee nesting site

    Bumblebees can sting repeatedly without dying, but none has ever threatened me. The ones you see sleeping in flowers in the early morning are probably males, because once they leave home, they don’t have a nest to go back to.

    I learned that except for rising queens, all bumblebees die at the end of autumn. A queen spends the winter underground, emerging early next spring to start her colony. 

Bumblebee on a crocus-photo Rasbak

She looks for a hole that another animal has made in the past or for some loose, open sandy or loamy soil where she can dig tunnels. Sandy loam is what I’ve got, but I tend to cover open soil with mulch. In future, I’ll make a point of leaving some unmulched areas for bee nesting sites. Meanwhile, the loose, uncompacted surface of the sheet compost mound is providing nesting opportunities.

    I’d thought bumblebees were solitary, but they live in eusocial colonies, where mothers and daughters work together to raise the next generation. With the results of her foraging, my queen will create nectar pots and pollen balls, lay her eggs, and seal each one in wax with some food for the larva when it hatches. When the larvae pupate and emerge as adult bees, those tapped to be next year’s queens will get more food and grow bigger. How does the queen decide which of her daughters will succeed her?

    Bumblebees are generalist pollinators: they visit many kinds of flowers, in contrast to some other native bee species that specialize on a few kinds of flowers. That’s why bumblebees are so useful to farms and gardens and why it makes sense to protect them by providing habitat and eschewing pesticides.

It's not hard for bees to find flowers in the garden in May. August will be more of a challenge.

Sheet composting begun

Blood meal came in the mail (sounds ominous, doesn’t it?), enabling my grand-dog Felix and me to start the sheet composting project. As you’ll remember, this is a technique for converting some lawn to expand a planting bed. We’d be applying layers of compostable materials to smother the grass and make rich soil for new native plants.

Purple coneflowers will be able to spread into the enlarged bed

    The first step was to mark off the grass section for execution. I did this using short stakes and some stretchy orange plastic surveyor’s tape. I can re-use the tape when this project is finished.

    After moving the stakes around to see how the edge of the new bed would look, I settled on a straight edge parallel to the nearby rectangular vegetable bed and 10 feet from the rabbit fence that protects that area. The ends of the new bed would curve into existing planting areas.

Orange tape marks the edge of the future planting area

    Next I sprinkled a dusting of blood meal on the grass and followed it with layers of newspaper. To pile them several sheets thick, I had to combine sections of the paper, overlapping them so no grass was showing. I avoided glossy supplements that might contain problematic inks. The paper wanted to blow around in the spring breeze but subsided with a generous sprinkling from the watering can. I laid down newspaper in three stages, weighing it down with the next materials before moving on so that the paper wouldn’t dry out and blow away.

I watered the newspaper to keep it from blowing away

    On top of the newspaper I spread a layer of composted cow manure. I had two bags left over from last fall, both open. Some of the contents were frozen, and I couldn’t break them up. I stood the icy parts in the sun to melt. 

Cow manure popsicle warming in the sun against the rabbit fence

In all, it took most of four 50-pound bags to cover the 120 square foot area with an inch of cow manure. I was treating the sheet composting recipe more like instructions for a stir fry than a fine pastry—just adding what looked about right.

A section of newspaper covered with cow manure

    Admonishing Felix not to dig through the manure-covered newspapers, which seemed to be an alluring possibility, I next turned to hauling wood chips from the big heap in the driveway. After many wheelbarrow trips, I’d dumped an 8-inch layer on top of the newspaper. 

Wood chip layer

I added a few inches of fall leaves that I raked from nearby beds, anchoring them down with more wood chips. That’s where the project stands as of Saturday afternoon: a long foot-tall mound of compostable layers, widest in the middle and tapered at both ends.

It doesn't look like much now. Give it two years.

    The next stage will be to pile on a layer of compost, which will boost the population of soil organisms to start the decomposition. The icing on the cake will be a topping of weed-free straw.

    Moving the wood chips wore me out, but the initial investment of time and energy seems like a small price to pay for what should become an area of great soil in a couple of years.

Smothering some lawn

On Friday Kevin Newman’s team did some long-overdue pruning in my yard. They cut out dead branches, pruned back our trees where they were hanging over the fence, and removed branches that had grown over our property from next door. They fed all the branches into the big chipping machine parked in the driveway. Before they left, they carefully dumped a portion of the chips in front of the garage.

A new trove of wood chips

    This puts me right where I want to be. I’ve got big plans. I’m going to add a big swath to one of the shrub and perennial beds by trying out sheet composting.

    The spot I have in mind is some lawn in front of the dawn redwood (Metasequoia glyptostroboides). When we planted the tree in 1997, it was slender and just 10 feet tall. Now it’s rooftop height and wider every year, with feathery branches overshadowing the perennials I planted around its base. By commandeering some of the lawn in front of this bed, I can grow plants that need more sun than they can get under the tree’s branches. And I can forward my mission to subtract lawn.

Now covered with snow, this patch of lawn doesn't know what's about to hit

    My planting plan for the new part of the bed is still vague. I’m picturing low native plants. I’ve got time to study my ecoregion’s plant community to decide what these should be. The flower color scheme so far has been blue and deep pink. I’ll try to harmonize with the dusky pink blooms of a growing patch of purple coneflower (Echinacea purpurea) at the front of the existing bed.

What goes with purple coneflower?

    Sheet composting is the same process that happens in compost bins, but spread out over a wider area. 

Master Gardener Eve Werner, Butte County, CA, demonstrates sheet composting over lawn

The technique I’ll use is adapted from Toby Hemenway’s permaculture book Gaia’s Garden. Usually I skip recipes for “lasagna composting,” because I can make compost more easily by dumping plant waste on the compost piles as it comes. This time, though, I’m going to try the recipe to speed things up. If I just put down a layer of wood chips and fall leaves, they’d take years to decompose.

Wood chips on paths decompose very slowly

Here’s the recipe from the ground up:

1) A thin layer of blood meal for nitrogen (Blood meal powder is a byproduct of slaughterhouses. It appeals more to me than a high-nitrogen chemical fertilizer, which could leach nitrogen into the groundwater).
2) A layer of newspaper, minus glossy supplements, an eighth to half an inch thick, to smother grass
3) Composted manure for more nitrogen 
4) Twelve inches of wood chips mixed with fall leaves
5) A couple of inches of compost to inoculate the pile with soil organisms
6) Two inches of clean straw that’s free of weed seeds

    It’ll take a couple of years for soil organisms to weave through these layers and convert them into rich soil. I can plant seeds and seedlings this year in pockets of compost. 

Tomatoes planted into sheet compost-photo Natureln

Bigger plants will wait until next year. Meanwhile I can gloat over the lawn decomposing underneath.