Composting 101 – What is Compost?

If you want to grow healthy vigorous plants, then you need to start making compost. It is the single best amendment to your soil that can be added. Compost is full of essential nutrients necessary for tall healthy plants of any kind!

The purpose of this article is to give you a comprehensive understanding as to what compost actually is, and how the composting process works.

In this article:

What is Compost

Composting is the process at where bacteria and microbes break down organic matter such as kitchen scraps into a stable and fertile humus medium, which is known as compost.

Compost is the byproduct and final, stable form or decomposed organic matter. Full of nutrients and extremely fertile, compost can help build fertile soil that is full of life and nutrients, lending itself to be consumed by plants.

==>RELATED: 17 Benefits of Compost

All organic organisms can be composted be it plant or animal. Although in general you should composting any parts of animals, meats, or cheeses due to the longer time they require to break down. But, given enough time, all organic matter returns to the earth.

Aerobic vs Anaerobic Compost

There are two classifications for the types of bacteria that will break down organic matter. Aerobic and anaerobic. The distinction between the two is of particular importance for gardeners.

Aerobic bacteria requires oxygen to survive. This type of bacteria gives off heat as it breaks down plant matter. It is generally known as the ‘good’ bacteria due to the speed at which it can break down organic matter. With a large enough pile, the temperatures can reach 130F (53C) or more which is generally enough to kill any weed seeds present. [1]

Anaerobic bacteria does not require oxygen. It also does not give off heat, which means it that any weed seeds present will be viable. Anaerobic bacteria takes longer time to break down organic matter. It also creates an unpleasant odor.

The four ingredients of compost

For composting to take place, you need the following ingredients:

  1. Nitrogen (green material)
  2. Carbon (brown material)
  3. Water
  4. Oxygen

With the presence of all four ingredients you create an environment for the composting bacteria to thrive.

How organic material turns into compost

Soil microorganisms, or bacteria are made of carbon and nitrogen. They also consume carbon and nitrogen to live. And these microorganisms require a moist but aerated environment to survive.

Soil microbes will consume Carbon and nitrogen to survive. The amounts of carbon and nitrogen is referred to the C:N ratio. The optimum C:N ratio for making compost is 24:1. [2] So, as these bacteria consume the material, the give off heat and carbon dioxide (CO2). However, a slightly higher C:N ratio will provide some excess nutrients for plants once the compost is applied.

What are the benefits of compost

The benefits of compost to plants and soil are huge! Compost contains essential plant nutrients and are available in a form for nearby plants to consume them. The bacteria present in compost further enhances the soils ability to breakdown other organic matter into usable, natural soil amendment and fertilizer for plants.

Benefits of Compost on crop yields

Studies have shown repeatedly that the application of compost results in larger plants and increased yields of fruits and vegetables [3]. The excess nutrients in compost become available for plants to utilize, resulting in larger more lush plants and their fruits. Topdressing of grass has been found to greatly improve the growth and color. [5]

Finished compost generally has carbon to nitrogen ratios (C:N) around 20. [4] Application of compost with a C:N less than 25 will result in excess nitrogen and other nutrients available for plants to consume.

I can confirm this from my own personal experience. The addition of compost to my former-turf-lawn vegetable garden has been critical to success. The more heavily I amended a plant with compost, the larger and more bountiful harvest I receive.

Benefits of Compost on Soil

Compost benefits soil in multiple ways. Besides enhancing the microorganisms, soil structure, and nutrients – Compost will enhance the drainage of clay soil and the water retention of sandy soil. Additionally, compost will reduce compaction within soil aiding the overall drainage and water holding capacity of soil.

Additionally research has found a negative correlation between soil penetration rate and bulk density decrease with the application of compost [4] (which is a good thing!). The research has also shown a positive correlation with soil porosity, infiltration rate, and aggregate stability increase with application of compost. This will reduce erosion and increase water holding capacity. [4]

What materials can be composted

While it is true that any form of organic material, be it plant or animal, can be composted, it doesn’t mean that you should compost everything.

Plant materials break down quickly. And some manures such as poultry, rabbit, and cow have high amounts of nitrogen making them an excellent source of green material.

*RELATED ==> See our comprehensive list of 101 items you can compost here

For brown materials, stick to plain paper products or pure wood sawdust or shavings. Don’t use plastic labels or tape that is often attached to cardboard boxes. Also, avoid any newspaper or cardboard that is glossy or has colored ink.

Related ==> You can read more about pollutant risks with using the ‘wrong’ cardboard or paper products here.

What not to compost

While bacteria and other microbes will decompose everything, proteins, meats and cheeses tend to take a very long time to decompose. So, to make sure you get your compost in a timely manner I recommend that you stick to plant materials or certain types of manures.

How to build a compost pile

Simply put, a mixture of shredded green and brown material thoroughly moistened and aerated is a compost pile. Layering, then mixing, and moistening is the proper steps to make a compost pile. Also, targeting a pile that is at least 3′ diameter (1 m) to help achieve sufficient bio-mass for the compost to heat up.

However, we have written a detailed step by step guide to making a compost pile. It is simple, to the point, and has pictures and video to help you out. You can read it by clicking on the link below:

How to Build a Simple Compost Pile, with Results and Video

Tumblers, bins, containers – different ways of composting

There are an infinite number of ways to compost. Some people use tumblers, bins, cages, or simple piles on the ground. There are pros and cons for each method, and you must carefully evaluate them to your own situation.

While tumblers are neat and clean (on the outside), and easy to turn, they also are costly and prevent worms from locating your pile. Alternatively, bins and piles can be unsightly next to a home, and moisture levels need to be managed more than a tumbler.

How to use compost

Compost can be used in many ways. I use mine for all sorts of different applications in my yard.

Top-dressing a garden with compost will increase the soil fertility and prevent weeds. The nutrients will trickle down into the soil beneath, and worms will help transfer organic matter deeper into the soil.

Top-dressing a lawn will result in a significant boost to the growth rate and color of the grass. [5] If the lawn is aerated prior to top dressing, it will help the compost reach deeper levels allowing for better water infiltration and water holding capacity.

==>See how to topdress your lawn with compost here

Amending soil with compost when planting new seedlings. By simply adding a handful of compost to the bottom of a hole, or mixing with the back-fill soil of a vegetable plant or flower seedling will result in larger, healthier plants. [3]

Applying a layer of compost around tree and shrubs (but not against the trunks) will act as an organic fertilizer, which will in turn help the tree achieve it’s full potential growth rate. I apply compost to my trees and shrubs each fall.


Learn more about Composting……


[1] Bob Bergland, US Secretary of Agriculture et al. REPORT AND RECOMMENDATIONS ON ORGANIC FARMING. USDA Study Team on Organic Farming, United States Department of Agriculture, July 1980

[2] USDA Natural Resources Conservation Service. Carbon to Nitrogen Ratios in Cropping Systems.

[3] Aziz Shiralipour, Dennis B. McConnell, Wayne H. Smith, Uses and benefits of MSW compost: A review and an assessment, Biomass and Bioenergy, Volume 3, Issues 3–4, 1992, Pages 267-279, ISSN 0961-9534,

[4] Craig G. Cogger (2005) Potential Compost Benefits for Restoration Of Soils Disturbed by Urban Development, Compost Science & Utilization, 13:4, 243-251, DOI: 10.1080/1065657X.2005.10702248

[5] Daniel Garling, Michael Boehm. Temporal Effects of Compost and Fertilizer Applications on Nitrogen Fertility of Golf Course Turfgrass, Agronomy Journal, Volume93, Issue3, May 2001,
Pages 548-555.

Joe Foster

Hi - I grew up outdoors in nature - hiking, fishing, hunting. In high school I got my first job at a garden center where I learned to garden and landscape. I've been growing plants from seed and designing native plant gardens for over 10 years. I hope to share some of my knowledge with you! You may have seen some of my videos I create on our YouTube channel, GrowitBuildit (more than 10 million views!). You can find my channel here: Additionally I am a wood worker / DIY enthusiast. I enjoy designing/building projects (with hand tools when I can!). I hope to give you some tips and useful information!

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