Tag Archives: compost

Compost – Carbon-to-Nitrogen Ratios

A couple of months ago I posted about Compost-What’s In and What’s Out.

However, it’s not enough that you throw your organics, food and yard waste into your compost bin (although it’s a good start!)  You must also be aware of the carbon to nitrogen ratio so as to keep your compost happy, healthy, and not stinky!  For best performance, the compost pile, or more to the point the composting microorganisms, require the correct proportion of carbon for energy and nitrogen for protein production. Scientists (yes, there are compost scientists) have determined that the fastest way to produce fertile, sweet-smelling compost is to maintain a C:N ratio somewhere around 25 to 30 parts carbon to 1 part nitrogen, or 25-30:1. If the C:N ratio is too high (excess carbon), decomposition slows down. If the C:N ratio is too low (excess nitrogen) you will end up with a stinky pile.

Below are the average C:N ratios for some common organic materials found in the compost bin. For our purposes, the materials containing high amounts of carbon are considered "browns," and materials containing high amounts of nitrogen are considered "greens."

Estimated Carbon-to-Nitrogen Ratios
Browns = High Carbon C:N
Ashes, wood 25:1
Cardboard, shredded 350:1
Corn stalks 75:1
Fruit waste 35:1
Leaves 60:1
Newspaper, shredded 175:1
Peanut shells 35:1
Pine needles 80:1
Sawdust 325:1
Straw 75:1
Wood chips 400:1
Greens = High Nitrogen C:N
Alfalfa 12:1
Clover 23:1
Coffee grounds 20:1
Food waste 20:1
Garden waste 30:1
Grass clippings 20:1
Hay 25:1
Manures 15:1
Seaweed 19:1
Vegetable scraps 25:1
Weeds 30:1

Note: Many ingredients used for composting do not have the ideal ratio of 25-30:1. As a result, most must be mixed to create "the perfect compost recipe." High C:N ratios may be lowered by adding grass clippings or manures. Low C:N ratios may be raised by adding paper, dry leaves or wood chips.  Many home gardeners will put up with a slight odor and keep some excess nitrogen in the pile, just to make sure there is always enough around to keep the pile "cooking!" Learn more about building a hot compost pile here.

Compost–What’s In and What’s Out

I’ve had a Mantis twin barrel composter for several years now, before that we used a couple of old tires stacked on top of each other to form a compost bin.  I’ve really enjoyed having a composter because it helps to reduce landfills and of course is “free” assuming you take care of your compost.  Interestingly the EPA says something along the lines of 27% of the US waste stream consists of yard waste and food.  Imagine if that went back into the soil!  we would reduce our land fill consumption by one fourth and of course have vibrant, healthy soil!  It is important when composting that you know what you should and should not put into your compost pile, here is  partial list of “good” stuff:

  • Cardboard rolls
  • Clean paper
  • Coffee grounds and filters
  • Cotton rags
  • Dryer and vacuum cleaner lint
  • Eggshells
  • Fireplace ashes
  • Fruits and vegetables
  • Grass clippings
  • Hair and fur
  • Hay and straw
  • Houseplants
  • Leaves
  • Nut shells
  • Sawdust
  • Shredded newspaper
  • Tea bags
  • Wood chips
  • Wool rags
  • Yard trimmings

And of course, a list of what not to put into the compost pile:

  • Black walnut tree leaves or twigs
    • Releases substances that might be harmful to plants
  • Coal or charcoal ash
    • Might contain substances harmful to plants
  • Dairy products (e.g., butter, milk, sour cream, yogurt) and eggs*
    • Create odor problems and attract pests such as rodents and flies
  • Diseased or insect-ridden plants
    • Diseases or insects might survive and be transferred back to other plants
  • Fats, grease, lard, or oils*
    • Create odor problems and attract pests such as rodents and flies
  • Meat or fish bones and scraps*
    • Create odor problems and attract pests such as rodents and flies
  • Pet wastes (e.g., dog or cat feces, soiled cat litter)*
    • Might contain parasites, bacteria, germs, pathogens, and viruses harmful to humans
  • Yard trimmings treated with chemical pesticides
    • Might kill beneficial composting organisms


Want to learn about how to get started at home?  Cornell has a pretty good PDF here: http://cwmi.css.cornell.edu/compostingathome.pdf

Giant Organic Pumpkins from Compost

Every year around this time, the great pumpkins come out. I’m not talking about THE Great Pumpkin from the Charlie Brown Halloween Specials, but instead the gargantuan pumpkins that people grow in various vegetable growing competitions.

Pumpkin Contest


HowToCompost.org has a contest every year for the largest pumpkin grown worldwide without the use of chemical fertilizers. Now my little pumpkin won’t win anything this year (especially as I didn’t actually enter the contest and it probably tops out at 20 pounds), but I think I’ll have to see if I have what it takes for 2008. The rules for growing the pumpkin are pretty simple.

  1. Use only compost to prepare your soil (no chemical fertilizers/supplements allowed).
  2. No force feeding of nutrients through the vines.
  3. The pumpkin must be grown outdoors. (Seeds can be germinated inside and transplanted outside in the early spring.


Composting is an important way to recycle and can be done at home. It is an easy way to reduce the amount of household garbage by about one third. As well, it produces a valuable soil amendment for use in gardening and landscaping.

Mantis ComposT-Twin

We have been using a Mantis twin barrel composter for about 2 years. It was a gift from both sets of parents for Christmas (it’s fairly expensive for what it is, but convenient and it actually looks good in the side yard). I absolutely love the idea of having our own compost right there and of the reduced footprint we have on our landfills. Until we got the barrel composter we were using the used tire method of composting. This was a good method, but was fairly labor intensive and we piled everything on from the top, so we had some problems with aeration.


Remember that compost is not just decayed organic matter. Composting is applied microbiology. Literally thousands upon thousands of different species of microorganisms (2 million individuals per gram) in a highly complex ecosystem.


I think one way of maintaining a sustainable lifestyle is that it must be as easy or easier than the more conventional approach. When collecting our kitchen scraps for compost, we keep a bucket under our sink next to the cutting board. Instead of taking scraps to the regular trash, they go there, when it’s full we take it out to the composter. This is just as easy as if we were tossing it into the trash can for pick-up. Yard scraps work just as well since we pile everything in and if it’s full we put the waste under the barrel and in a couple of days the compost has “cooked” down to where we can stuff more in. It is an easy way to reduce the amount of household garbage by about one third.

Now the website says that you should turn the composter every day – in reality we only turn it when we are dumping in our scraps and that works just as well. And of course the advantage of the twin barrel is that we can just keep filling and filling one chamber while the compost spends several weeks cooking in the other.

Producing quality compost is the most important job on the organic farm. A lot of the problems I see on farms I visit could be solved by making better compost.

— Elliott Coleman, The New Organic Grower

How to Compost

Here’s some great tips for what to compost and how to compost in your back yard. You don’t need to go out and buy a big barrel composter like we’ve got, but you should definitely try it out and see if it’s something you enjoy!

What to Include

  • From the Garden
    • Leaves (chopped – to speed their breakdown)
    • Grass (not wet)
    • Plants & Weeds (without ripe seeds)
    • Old potting soil
    • Soft plant stems
  • From the Kitchen
    • Fruit scraps
    • Vegetable trimmings
    • Egg shells (crushed)
    • Tea bags
    • Coffee grounds with filters
    • Shredded paper

DO NOT include…

    • Meat, fish and bones
    • Plastics
    • Metals
    • Fats and oils
    • Dairy products
    • Pet waste
    • Cheese, meat or other sauces

Clues on Composting

  • The composting process works best when the organic pieces are small. Weeds and trimmings should be shredded.
  • Don’t add thick layers of any one kind of waste. Grass should not be more than 6 cm deep, leaves up to 15 cm deep (cut or chop or dry and crumble them). If you can, let grass dry first or mix it with dry, coarse material such as leaves to prevent compacting.
  • The composter contents should be moist like a wrung-out sponge. If the contents are too dry, it will take overly long to compost; and if too wet, the contents may begin to smell.
  • Turn or mix the compost every couple of weeks or each time you add new material. This keeps the compost well aerated.
  • Composting can be done in the winter. You can add materials to your composter all winter long. The breakdown process slows down or stops when the pile is frozen, but it will start up again in the spring. Thorough turning in the spring will reactivate the pile. Empty the composter in the fall to make plenty of room.


Composting is not difficult but sometimes the process requires a little extra attention. Here are some easy solutions to correct certain situations which might occur.

  • If the pile does not decrease in size or generate heat, composting may need a boost. If the pile is dry, add water – mixing thoroughly. If the pile is wet and muddy, spread it in the sun and add dry material. Remember to save “old” compost to mix with incoming material.
  • If the center of the pile is damp and warm, but the rest is cold, the pile may be too small. Try to keep your composter as full as possible. Mix new with old, dry with wet, breaking up mats and clumps.
  • If the pile is damp and sweet smelling but not heating, it may need nitrogen. Add grass clippings, table scraps or a sprinkling of organic fertilizer from the garden centre.
  • If the compost pile develops a foul odour, it may not be getting enough air. Loosen up the pile, break up clumps, unblock vents and perhaps add some wood chips to help the pile “breathe”. Turning the pile always helps aeration.
  • Compost in a container with a cover to prevent animals from getting into the composting materials. A wire mesh around the base can help to prevent pests from digging under the pile. Dig in or cover food waste immediately.

Is It Finished Yet?

The composting process can take from 2 months to 2 years, depending on the materials used and the effort involved. To accelerate the process, the pile must be a balance between wet and dry material, turn it frequently and make sure the waste is shredded or in small pieces.
Compost is ready to be used when it is dark in color, crumbly and has an “earthy” smell.

Put Compost to Good Use

Composting can benefit your soil and plants in many ways. It increases the soil’s organic matter content and its moisture-holding capacity. Compost improves soil porosity and helps to control soil erosion. It also enhances plant and flower growth and helps plants develop a sound root structure.
Use it on your lawn, in your garden, around trees or combine it with potting soil for your plants.