Composting Basics - Three Primary Elements: Food, Water and Air

The Composting Basics are all about creating a good habitat in your compost for the organisms that work in the decomposition cycle. Compost is a living ecosystem that supports a complex web of microbes and other organisms. Like you and I they need food, water, and air. No matter what method of composting you choose you will need to pay attention to and supply these composting basics or life essentials.

So... what are the implications of the fact that compost is alive? And in our composting how do we supply the basics of life for this living system.

What Exactly is Compost?

When I first started seriously gardening I spent a lot of time with Catherine, a wonderful artist and a great gardener. She always started a garden bed by throwing a layer of compost on it. By contrast, my family tended to buy a load of topsoil every two or three years. We'd replace the soil and then sprinkle a generous topping of 20-20-20 fertilizer on top. Catherine's garden was great, my family's garden was kind of lame.

Many of us tend to use numbers to compare things. The three fertilizer numbers refer to the percentage of N (nitrogen), P (phosphorus) and K (potassium) they contain so in my old book 20-20-20 was darn good. I was very surprised to find that Compost was only about 1-1-1. Compost gets creamed in the NPK numbers game.

So why does compost make Catherine's garden great, while my parents brand new topsoil and 20-20-20 fertilizer made a wimpy plant plot.

The story of compost is best told with a microscope. You might find pretty crystals in the 20-20-20 fertilizer but you won't find any life. Under the scope, your compost will be teeming with huge populations of an incredibly diverse number of species. In compost you have a whole ecosystem - or put another way - the makings of a soil civilization.

These micro herds may not have chemistry's big three but they do have the means to mine those nutrients from the soil and bring them to the plants in your garden. Compost is a diverse symbiotic community capable of

  • mining the soil for nutrients,
  • transforming the nutrients into food plants can use,
  • storing the food close to the plants so it's handy when needed,
  • conditioning the soil so roots can grow deeply into it, and helpful microbes have a home,
  • storing a water reservoir and,
  • fighting disease and healing sick plants.

By comparison your 20-20-20 fertilizer is a fast food meal gulped down in the car while driving to your next appointment .

The Composting Basics or Care and Feeding of the Compost

Compost is such a miraculous substance it is well worth the effort you put into making it. The fact that you make it from readily available ingredients you'd otherwise throw away is a bonus.

Composting Basics #1 - Feed Your Compost a Balanced Diet

The materials you add to your compost pile or bin are food for the organisms that actually make the compost. It's helpful to categorize these materials based on their carbon nitrogen ratio. All living things on earth have both nitrogen and carbon in them. Those materials with a ratio below 30, or 30 parts carbon to 1 part nitrogen are considered high nitrogen inputs and are called greens. Those with higher ratios are high carbon browns.

Common C/N Ratios

Most of us get the lion's share of our material from either the yard or the kitchen.

  • Yard and Garden Waste Your grass clippings, green weeds, and most garden trimming are greens. Fall leaves, dead dried plants are browns
  • Kitchen Waste Your food waste including fruits and vegetables as well as meat and dairy leftovers would all count as greens. It is often recommended that meat, fish and dairy be left out of the compost, but with care you can compost them. Dirty paper napkins, used kleenex, the rolls from toilet paper and paper towels, as well as shredded paper from the home office can make up part of the compost browns.

Check out our compost ingredients page for more information. There you'll find the C/N ratio of common ingredients and links for tips on how to manage some of the more challenging materials.

One last point - the compost process can break down most pesticides and herbicides. However, there are some very persistent herbicides that break down only very very slowly. Make sure any hay, straw, manure, or grass clippings that you are processing have not been sprayed with one or other of these. Our page on picloram and others will tell you what to watch out for.

Composting Basics #2 - Is Your Compost Thirsty or... Drowning?

All life here needs water and the microbes, insects and worms working your compost are no exception. A moisture level in the range of 40 - 60% is ideal.

If you have a moisture meter you can use it to measure the levels. The rest of us can use a touch test. The compost materials should feel as wet as a squeezed out sponge. With too much moisture add dry brown stuff, too little add water.

Strategies for moisture adjustment depend on the climate you live in. In my area, 90% of compost problems are caused by too little moisture. Those living in more humid areas will need to make sure things don't get too wet. Check our compost moisture page for more tips on keeping the right moisture levels in the compost.

Composting Basics #3 - Can Your Compost Breathe?

Ideally you want good oxygen levels throughout your compost bin or pile. As your compost rots down it will shrink. In many cases the oxygen gets used up and your aerobic microbes die.

Add air when this happens - one way by turning the compost. You can also build your compost to help keep air pockets in the middle of the compost. You'll find composting tips for keeping air in your compost on this page.

Bokashi composting is one exception to this rule. It is a two step process which ferments various food wastes and then finishes the process by burying or composting the pickled material. This is an anaerobic process and done well is an excellent method for handling food wastes. See our step by step Bokashi pages for help.

Final Words

No matter how you decide to compost remember first that your compost is a living system. Then treat it with the care you already give your garden plants or perhaps your puppy. If your composting provides the basics of life you can't go wrong.

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