The Composting Process

I’ve seen in your videos where carbon dioxide is released into the atmosphere during composting. Isn’t this a dangerous greenhouse gas that contributes to global warming?

Yes, CO2 is released, but since it is part of a natural process, it isn’t considered man-made; therefore, it isn’t figured into greenhouse gas emission calculations. Actually, composting, when done properly, as with our Advanced Composting System, reduces greenhouse gases a great deal, (especially methane and nitrous oxide, which are considered far more dangerous than CO2) when compared to simply dumping an equivalent amount of organicwaste into a landfill.

Read more! Download this factsheet from the U.S. Composting Council >> (USCC Fact Sheet, “Greenhouse Gases and the Role of Composting: A Primer for Producers,” Copyright US Composting Council 2009. For more information, visit

Do fabric covers offer a benefit to the process?

Fabric covers, because they help control the process, offer a spectrum of benefits to raise quality, consistency, and predictability in the finished compost product. Those benefits include:

  • Moisture management — If the climate is wet, excess moisture is kept out of the windrow; if the climate is dry, moisture is retained within the row.
  • While shedding rain, gaseous exchange is still permitted.
  • Nutrient retention is higher in covered compost than uncovered.
  • The compost cycle will finish sooner.
  • Ultra-violet ray damage is minimized.
  • Covered compost retains temperature levels better than uncovered. In freezing conditions, covered compost does not freeze as deeply during winter and warms faster in spring.
  • Leaching is significantly reduced when compost is covered.

You may want to visit the McGill University study regarding compost covers which can be found on our University Research page.

What is the significance of the shape and size of a windrow?

To generate the heat necessary for speeding the decomposition process and degrading undesirable elements, the windrow should be four to six feet deep. If the windrow is too flat or spread out, required temperatures cannot be achieved. The inverted “V” of the ACS process creates the desired chimney effect. If the row is too high (above 6 feet), anaerobic conditions can easily set in.

Aeromaster drum tines are engineered to gently lift and turn the compost row’s perimeter towards the center of the windrow while moving middle materials to the perimeter. Proper turning aerates (exchanges CO2 out for O2 in), blends materials (providing for maximum interaction between carbon and nitrogen atoms), and shapes the windrow without the use of external shields or curtains (which limit humus formation by the destruction of aggregate crumb structure).

What should I know about windrow temperature?

To have a controlled process producing a high quality end product, a predictable temperature curve is required. Temperatures are primarily controlled by the C:N (carbon to nitrogen) ratio of the feedstocks. If the ratio is too high, temperatures will be low. If the ratio is too low, temperatures will go too high (which limits humus formation and significantly lowers the soil and plant benefit of the finished compost product).

A good temperature cycle will have windrows in the 131° to 150° F. (55 -66° C.) range for at least 2 weeks and progressively declining thereafter. If temperature stays in this thermophilic range for longer than 2 weeks, that is preferable to their declining prematurely. If temperatures are too low, pathogens, chemical and pesticide residues, in addition to weed seeds and other undesirable constituents will not be destroyed. If this occurs, minimum EPA quality standards will not be achieved. (Remember that EPA standards are much lower than MBS’ standards regarding compost quality.)

Temperatures are affected by the feedstocks used, their ratios in the windrow, their individual decomposition rates, moisture levels, and access to oxygen. Microbes added to the row and compost windrow covers can also be determinants.

Can I eliminate odors from the windrow?

Odor control can be achieved in 2-3 days after beginning the ACS composting process. Odors result from the nitrogen forms of the feedstocks used. If the nitrogen is in the raw forms of ammonium or ammonia, these highly volatile gases emit unpleasant odors. If these raw forms are converted to the stable nitrate, odors dissipate. MBS will teach you how to manage the nitrogen cycle. Anaerobic metabolism is the prime contibutor to odors. Aerobic metabolism produces odorless forms. 

I’ve heard that inoculants don’t really make much difference… is this true?

Misconceptions abound regarding the use of inoculant. They include:

“Inoculant is applied to raise the heat in the compost.” Incorrect. Heat will rise to the desired levels primarily because of the interaction of the carbon and nitrogen atoms apportioned in their desired ratios in the feedstocks due to microbial decomposition activity. Inoculant, rather, is applied to ensure that appropriate “breakdown” microbes are present for purposes of decomposition (e.g., cellulose and lignin digestors).

“Inoculant (often misnamed ‘compost starter’) only works in the beginning ‘breakdown’ phase.” Incorrect. ACS inoculant offers a wide range of proven beneficial microbes (plus an enzyme booster) which each go to work during their respective temperature phases of the composting cycle. There are both breakdown (decomposition) microbes and build-up (recomposition) microbes present for beneficial humus building.

“Inoculants do not make a signicant difference.” Depends. Composters who do not see differences usually do not have the ability to get equal microbial distribution throughout all parts of a windrow. The microbes do not migrate well, so if they are only applied to the perimeter of a row, much of the windrow will not benefit. Using an Aeromaster turner avoids this problem as each particle is inoculated while it passes above the turner drum.

As with all composting, a proper environment must be regularly maintained (temperature, aeration, moisture) for the microbes to flourish and provide their desired impact.

Not all inoculants are created equal. Some have better quality and diversity of species than others. That’s why we sell our own ACS product.

“Inoculants do not pay for themselves.” Not true anymore. When composters utilize the revolutionary AEROMAX system, the cost of inoculant drops to less than 30 cents per cubic yard (better than an 80% saving from previous inoculation methods). Proven beneficial microbes pay for themselves several times over. They not only improve breakdown, but build-up, humus crumb development, species quality and diversity, increased nitrogen retention, provide consistency for the composting process, and shorten the length of the composting cycle.

“Inoculants do not store well.” Incorrect! ACS “Compost Finisher” is freeze dried and can be stored indefinitely.

Can I mix MBS composting inoculants directly with litter/manure?

This will work fine for the N Converter, but not for the humifier and finisher. You’ll want to mix those only with water.

Why should a compost process be aerobic?

There are numerous reasons why an aerobic process will yield superior results, both during the composting process itself, the quality of the finished product, and its ultimate benefits to the soil.

  • It has been said that, by the composting process, you are “growing microbes.” Beneficial microlife are perhaps the most important factor in having fertile soil. But those beneficial microbes need oxygen to function efficiently in the compost windrow. If they have access to oxygen, they can feed and grow through the pile. But if they are cut off from oxygen, they die in their own excrement.
  • Beneficial Humus development is enhanced when there is a controlled exposure to oxygen. Humus is the reservoir for soil nutrients.
  • In volatile compounds, aerobic metabolism is odorless while anaerobic metabolism produces odors.
  • Aerobic bacteria feed on carbon and cause the soil to crack, making possible the entry of air into the soil (breaking up compaction).
  • Aerobic bacteria take humus and convert it to energy for the plant.
  • Microorganisms that require high oxygen availability improve the energy level in the soil. Microorganisms living in the absence of oxygen usually decrease soil energy levels increasing hydrogen levels.
  • The recommended ratio of aerobic organisms to anaerobic organisms is 10:1. In a balanced environment, anaerobic organisms begin necessary and important functions where aerobic organisms then finish the job.

How should I interpret 7130 ppm as a sodium result in the Chicken Manure on my feedstock report? Why is the sodium level tested anyway?

Sodium is something that we monitor because we know it will impact whether or not we can make Humus Compost.

Humus formation is Polymer formation. Polymer growth comes from microbes that specifically manufacture polymers. They cannot do it in a salt toxic environment. The reason there is no desired level is that you usually do not have a lot of control over how much sodium is in any particular feedstock. So the solution test is there to evaluate how much is in it and then decide what percentage that feedstock should be utilized in the overall recipe, in other words to manage the overall salt levels.

If you are striving to manufacture Humus Compost, 7130 ppm is not too much. Use it at less than 35 percent of the entire recipe. If your goal is a little less lofty, and you are looking to make “very good” compost as opposed to Humus Compost then you could go up to potentially 70% in the recipe.

Can blood be composted in with residues and manure? Is sterilization necessary?

Blood can be an ingredient in a balanced recipe. It is a nitrogen source and thus would need to be accompanied by adequate available carbon. Sterilization will then occur naturally with adequate heat.

However, some areas of the windrows may not get hot enough to destroy the blood-borne pathogens. For this reason, it is recommended that the blood be pasteurized.

Apply the blood only in the first week of composting, regardless of pasteurization. Apply through the existing water manifold and nozzles to distribute it evenly on every particle.