What is Compost? A Complete Guide to Composting

All Composts are NOT Created Equal

For our first blog entry, we would like to talk about a very near and dear topic to us at Amended Soils – compost!

What is compost?

The compost definition was recently redefined by The American Association of Plant and Food Control Officials and recognized by The US Compost Council; “is the product manufactured through the controlled aerobic, biological decomposition of biodegradable materials. The product has undergone mesophilic and thermophilic temperatures, which significantly reduces the viability of pathogens and weed seeds, and stabilizes the carbon such that it is beneficial to plant growth. Compost is typically used as a soil amendment, but may also contribute plant nutrients.” (1)

Prior to April 2018, the definition was much vaguer allowing products to be called “compost” that would not qualify under the current guidelines.  It did not require products to have specifically undergone certain stages crucial to the development of true “compost”. Just creating piles of the decaying matter was sufficient enough for most.  This allowed inferior or inadequate products to propagate the market with both small and large scale agricultural consumers and their crops suffering as a result.

So then what IS compost?

To start composting, you want a mix of “brown” and “green” materials, with a higher mix of brown.  Brown materials, such as leaves, wood shavings, wood ash, paper, and cardboard are all examples of brown materials. They provide the carbon for breaking down over time and also provide energy for the compost microbes. (2)  Green materials, such as grass clippings, vegetable peels, feathers, seaweed, plant cuttings consist of high nitrogen and protein sources vital for the compost microbes, accelerating the decomposition process. Manure is an excellent green material, and at Amended Soils, we use chicken manure from egg-laying hens, the most nutrient-rich available.  A minimum pile of 3x3x3 (feet) is needed, otherwise not enough heat will be generated for an efficient breakdown, or it will rapidly cool before the processes had completed. (3) There is no maximum size for the pile, but to ensure anaerobic environment (airflow and oxygen reaching all parts of the pile) and prevent too much water retention, manually working the pile or “turning” is required at regular intervals. Bulk providers such as Amended Soils utilize this process.

There are four stages to the composting process (4):

  1. The mesophilic phase
  2. The thermophilic phase
  3. The cooling phase
  4. The curing phase

Compost bacteria in the pile combine with oxygen and carbon to produce carbon dioxide and energy. These are mesophilic bacteria and as they proliferate their energy raises the temperature of the pile up to 111* F.  This is the Mesophilic Phase of composting.

As the temperature continues to rise, very active Thermophilic microorganisms take over, producing a lot energy and heat. During this phase, the heat given off by them will raise the temperature up to 160* F.  This may happen very rapidly, and can last for anywhere from days to months depending on the size of the pile and materials used. This is the Thermophilic Phase.

At this point most of the readily available green materials have been broken down, especially the manure, lowering the temperature of the pile. But there is still plenty of food left, and many of the coarser green materials or lignin from them have not. Microorganisms chased away by the heat, come back to go to work breaking down those materials. Fungi and other microorganisms such as Earthworms move in as well. This is the Cooling Phase of compost.

The last phase, the Curing Phase is one of the most crucial and also the one consistently avoided or cut short by large scale commercial and municipal compost producers.  The curing phase will see the temperature of the compost continue to decrease but also aid immensely in pathogen destruction and maturity, making the compost safer for your plants or crops.  It can take up to a year for some composts to cure, and most commercial and large scale compost providers don’t have the time or space to wait that long as more compost base products are brought in and client demand increases.  So they continue to push it out even when not completely ready. This is especially prevalent towards the end of a season, for example with vineyards. Generally, the winter is a slower time for vineyard composting, so providers can build up stock and allow their existing inventory to fully mature.  That translates to more fully developed compost going out in the spring and early summer. You will see lower temperatures, green materials broken down more, and a better product overall. But as demand continues to exhaust the aged supply, then spikes during the historically busier fall season, the compost providers are forced with a dilemma: tell their customers they have to wait for the compost to cure, or give them what they have!  Who wins in this scenario? No one! The provider puts out a substandard product, while the customer’s plants and crops will suffer.

So why is Amended Soils any different? We are also a bulk supplier, after all.  First, we have chosen to use the finest, organic, sustainable ingredients for our composts. We start with the aforementioned first source chicken manure from egg-laying hens, widely considered to be the most valuable, richest manure available. It provides more nitrogen, phosphorous, and potassium than any other manure.  It also rich in other minerals such as calcium increases the water holding capacity and beneficial biota of soil. (5) We use redwood shavings to support our carbon, and inoculate our piles with Bio-Char early in the process, allowing them to mature and activate together, improving nitrate leaching and NH3 emissions. (6) We do not use or allow bio-solids in our compost. (7)  We do not utilize grape pumice in our composts, which not only take longer to break down in a compost pile, but also carry the risk of disease or infestation of Meal Bugs or Grape Phylloxera transmission from one vineyard to another. (8) We also have multiple facilities from which to manage our inventory, allowing us the flexibility that others for full mature compost that others don’t.  Lastly and most importantly, is that we recognize our product availability is finite and refuse to issue anything we would consider sub-standard. Our products although large scale, are of limited quantity and we would rather tell a customer honestly that we are sold out of our finished product than allow the release of anything less.

It’s that open honesty, combined with our quality and service, that truly makes Amended Soils, A Better Blend.










Send comment