Ask Master Composter Joshua

A well built compost pile will hit at least 150 degrees. Photo by Scot Nelson, shared via Flickr.

We’re going to start a new series called “Ask Master Composter Joshua.” So throw us your composting questions!

Hello and I hope all is well with you on this raining morning. I have composting issues. I’m the only one I know that can not compost. I had some that I aged for about a year that I added to part of my garden soil this spring and it has pretty much killed everything… Seeds won’t germinate and healthy plants shrivel up and die. There are not even weeds…

I currently have a plastic spinning bin compost container that I am using for all my composting needs. I have been thinking about using two composting areas instead of one. One for yard and chicken manure and one for kitchen scraps. I like the green cone compost containers, but don’t really want to spend $100 on each one. I remember that you have on your blog that you buried garbage cans in your yard for composting.  Is this were you compost your kitchen scraps? Is it the same method as the green cones? Do you have holes on the bottom or also on the sides? How far into the ground do you bury your garbage can. How full do you fill it? How long before you harvest? Can you compost chicken manure and yard waste or just table scraps.

Happy farming! –Jilene

Hi Jilene, I see two big questions in your post. We’ll start with the first:

Why is my compost apparently killing my garden?
Compost is just broken down organic matter, an important component of all soils. In a natural environment, compost is generated naturally as plant and animal detritus decomposes. Once this detritus has been fully decomposed, it represents a stable, steady food source for your plants. But while it’s decomposing, it has the potential to “tie up” important nutrients that your plants need to grow. For example, uncomposted leaves will temporarily tie up nitrogen if dug into the garden. Nitrogen is important to photosynthesis, and plants grown in soil with no available nitrogen will not thrive. Or if you’ve made your compost from chicken manure, the uncomposted manure may be too strong (too high in nitrogen) and can chemically “burn” your plants. Chicken manure (with its bedding) should be combined with an equal volume of carbon-rich brown materials (such as fallen leaves) and will compost fully within a few short months if kept properly moist.

Was your compost fully decomposed? You say you aged it a year, but I see you used one of those elevated rotating bin composting systems.

The tumbler is prone to drying out.

Those systems are famous for drying out, and it could be your organic material simply sat there, inert, for a year and was only finally able to begin composting when you put it on your garden. Compost-in-progress should be kept “as moist as a wrung-out sponge.”

A second scenario is that a broad spectrum herbicide managed to find its way into your compost, and later into your garden. I would not suspect this unless you’d used non-organic (and thus herbicide-treated) straw in your compost. This is a major reason to use organic straw as your chicken bedding. Many such herbicides survive the composting process. And finally, nature sometimes makes its own herbicides. Certain plants, such as laurels, eucalyptus and black walnuts, are allelopathic. That means they create a toxin in their leaves that prevents other plants from growing. Personally, I compost these alleopathic materials without problem and suspect the toxins break down quickly, but there’s a chance alleopathic compounds could have made it into your garden.

And finally, your problem might not be related to compost at all. We’ve had a couple of rainy years, and over time this raininess increases the acidity in our soil (actually a decrease in pH). You have to add agricultural lime, dolomite lime, or gypsum every few years to offset this gradual acidification, at least if you want to grow non-native plants. A proper soil test from a lab would help you identify this problem.

Of all your symptoms, the complete lack of weeds is the most puzzling. There is a weed for every soil type, and homemade compost is usually full of weed seeds that would thrive in any type of soil you could possibly create. For this reason, I suspect herbicides. But I would still expect some grasses to germinate. A more extensive lab test could detect some major pollutants, if this problem persists into next year.

What exactly are green cones?
Your second question concerned green cones and buried garbage cans. These systems are a great way to deal with food waste, which would otherwise attract rats to a compost pile. The holes in the sides of the can – or the “buried laundry basket” type enclosure that lies hidden below a green cone – allow worms to crawl in and out of your food waste, but keep rats out. (In some ratty areas you may have to further predator-proof a green-cone by surrounding its buried basket with 1/2 inch galvanized hardware cloth).

A great way to deal with table scraps

If you choose to use a garbage can, you can bury it all the way if your soil drains freely. But if water accumulates, you’ll want to raise it a bit so worms can climb out of the water (and onto your pile of undigested food) if the container floods. I like to keep two green cones or buried garbage cans. I fill one for six months, then move to the second while the first digests. Then I harvest from the first, and begin refilling it again while the second cone is digested. To fill your green cone or buried garbage can, simply open the lid and scrape food inside. Then close the lid. It’s that simple. Other items, such as chicken manure and yard waste should go into the compost pile. That’s because a well-built compost pile will heat up to 150 degrees – that’s too hot for the worms that populate a green cone.

Where to go from here.
If your problem was related to improper composting, don’t worry, your garden should recover in time for a fall crop. If it’s herbicide related, you may have a longer wait. Start your seeds in trays, to give sensitive seeds an advantage before being transplanted into potentially inhospitable soil. Grow a cover crop if you can and let the garden go fallow for a year. If you haven’t added lime, purchase some from your garden center and apply at the recommended rate.

Compost pile. Photo by Milkwooders, shared via Flickr.

Composting is essentially a simple process, once you get the hang of it. It makes gardening easier, as compost helps protect your plants through droughts and nutrient imbalances. To keep your composting simple, follow these three guidelines:

  1. Build your compost pile by mixing equal volumes of organic green and brown materials. (Bonus points for chopping your material with a machete ahead of time.)
  2. Keep it moist as a wrung out sponge. Some old cardboard on top will help. Let it sit, 3 months if you turn it regularly with a pitchfork, 6 months to a year if you don’t.
  3. Divert table scraps to a separate, rat-proof system such as a green cone or buried garbage can.

9 Responses to Ask Master Composter Joshua

  1. Joshua –

    Thanks for answering my questions. I did accidentally purchase cedar shavings instead of pine for my chicken bedding last year. And being on a budget just used them. Would that be the reason for possible herbicide? Is there a test I can purchase to see if my soil does have herbicide? If my soil does have herbicide in it that would defeat the purpose of buying organic seeds and plants… Dang it! I now use shredded paper for my chickens bedding (not any shinny paper).

    Thanks for the Lime tip. I’ll get a soil PH test kit and see if it needs any lime (which it sounds like it does).

    I think I’ll bury a garbage can or two. Then at least I’ll have some kitchen scrap compost that I can use.

    I guess I can look forward to next year… What a great learning experience.

  2. Joshua McNichols

    I just did a web search and it sounds like cedar shavings may contain allelopathic compounds, which means they contain a natural herbicide. I also read that cedar shavings can take an extra long time to compost (and break down these compounds). This is the very reason people like to use cedar for planting beds – it resists decay.

    If this is indeed your problem, try digging some lawn clippings into your garden to speed the decay of the high-carbon, uncomposted cedar shavings. Keep the bed slightly moist and periodically apply a mixed cover crop. When one generation of cover crop has successfully matured, you’ll know you’re in the clear again. You may want to just let the cover crop stay on the bed through the winter and start over next spring, since by that time it will be pretty late in the year.

    Herbicide tests are done in labs, and cost a lot more than a standard test. I think you don’t need one, as cedar appears to be the problem. Home pH kits are notoriously inaccurate – you may want to get a professional test every few years and in years between just apply lime at the standard recommended rate for your region.

  3. Thanks ;)

    I added lots and lots of shredded paper and water to the compost I have in my tumbler yesterday. I looked at it this morning and it looks MUCH better already! I’ll add shredded paper and grass clippings to my garden beds and start looking at different cover crops (I didn’t realize there were SO many options). I like the idea of over wintering the cover crop and starting over in the spring.

  4. Joshua McNichols

    Just get a cover crop mix – a typical mix will contain cereal grains (rye, oats, something like that) and legumes (peas, vetches, clovers). That way you’re giving yourself the best possible chance of germination in your temporarily inhospitable soil.

    If your problem is allelopathic cedar, then you need grass, not paper, to further break down the cedar in the soil. It’s about achieving the proper ratio of carbon (cedar, paper) to nitrogen (grass, chicken droppings) in order to achieve compost. An extreme excess of either of these two elements could be the cause of your stunted garden. But an excess of carbon seems more likely, which is why I recommended grass clippings to accelerate the breakdown of the allegedly allelopathic cedar.

    There are some things you can do to check if your compost in your tumbler is too high in nitrogen or carbon. If, after you’ve kept it moist for a few days, it fails to heat up (stick your hand in the center – it should be warm), you need more nitrogen. If it smells like ammonia, you need more carbon. If it heats up and doesn’t smell, you’ve hit the balance of these two elements just right.

  5. Grass… got it. :) I’ll add some tonight.

    Maybe I’ll get a thermometer instead of sticking my had in the chicken poop compost… ha ha ha. Does that show my city girl side or what!

  6. I added grass clippings and water and mixed it all together really good and let it sit for a few days. This morning I turned the pile again and guess what I saw? Steam! Yes, that’s right, steam! It also looks so much better already. It’s a deep dark wonderful brown. And it doesn’t smell at all. I think I got it! I am SO SO excited. Thank you Master Joshua!

  7. Joshua McNichols

    Great news! Steam is a good sign.

  8. Can you compost chicken poop in a green cone? Seems good since my dogs want to the at the poop. The would be mixed with pine shavings. What’s the best way to do it?

    • Annette Cottrell

      Hi Jenna, absolutely!! You could also just get some hog wire and bend it into a cylinder and pile the wood shavings and poop (aka soiled bedding) in there to keep your dogs from eating it.

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