Questions and Answers About Using Compost

What constitutes high quality in finished compost?

Compost quality cannot be measured merely with a look at its color, a sniff, and a feel. Neither can it be established by what is not in it. Of course the appearance needs to resemble crumbly moist soil, but its performance needs to be evaluated. How will the compost affect plant growth? How well was the organic material converted to humus? The product needs to have the energy to support plant growth for many months.

Thorough laboratory analysis has been designed specifically to analyze compost, evaluating how effective the compost process was in allowing beneficial biological activity. Quality can be established by testing for:

  • Phytotoxins
  • Nitrogen cycle
  • pH level
  • Sulfides
  • Sodium and other salt levels
  • Energy indicators
  • Germination
  • Pathogen screening
  • Number and diversity of beneficial organisms
  • Aerobic to anaerobic ratio of ten or more aerobes to every anaerobe

Microscopic examination should show crumb structure (soil aggregation) composed of a wide variety of beneficial microorganisms, packed with nutrients in a stabilized (non-leachable) and root-friendly form. High quality compost will germinate any variety of seed at full strength.

Ranges in compost vary from benign to very beneficial and valuable. A high quality compost can be used for any type of plant propogation.

Midwest Bio-Systems’ unique Value Point System provides recommended uses for every product tested through our system. Samples achieving certain point criteria receive an ACS Seal of Quality certificate along with suggested applications.


Can high quality compost be used along with fertilizers?

Yes, and savings are realized as fertilizer inputs are reduced as soil health is built over time with repeat compost applications. Even with the first application of compost the amount of fertilizer used can and should be reduced.


What is humus, how is it formed, and why is it important?

Humus formation is the return of formerly rich, fertile soils to their original state. High quality composting is simply reversing the process of soil “mining” where nutrients and beneficial properties are removed or altered. Degradation has taken place, but the process is being reversed through the addition of high quality compost.

A high quality compost will provide some immediate humus benefit while also adding yet-to-be-humified organic matter for further decomposition. Humification is the passing of organic matter through the stomachs of certain beneficial microbes.

It is incorrect to identify organic matter (OM) and humus as the same thing. Organic matter is to humus as wheat is to bread.

In testing, optimal humus numbers are in the 50-80 range. Humus quality is actually more meaningful than quantity. If humus numbers are well above this range, it indicates the presence of many loose ions. So more is not necessarily better.

We like our humifying process because it is faster than what occurs in nature and offers a predictable outcome. Our composting cycle is typically an 8 week cycle, depending upon the materials composted. Natural processes without the aid of a controlled, accelerated process may take several years. Our process adds proven beneficial microbes both during the breakdown and build-up phases to help control the process. Recipes (the mixing of various organic feedstocks) have been carefully controlled to achieve the desired end.

Our Aeromaster equipment helps ensure proper mixing and blending, an aerobic atmosphere, and an optimal moisture environment. Essentially we are trying to create the ideal environment for beneficial microbes to reproduce and work.


What is a recipe and how is it formulated?

An ideal recipe (apportionment of compost feedstocks) should have:

  • A C:N ratio in the range of 25-30:1
  • A structure which is not overly dense
  • Carbons and nitrogens which decompose at similar rates
  • About 50% moisture (can be added after windrow is formed)
  • Ratios of feedstocks are determined by volume, not weight
  • Clay, finished compost, and/or inoculant added to the row

If you purchase Aeromaster turning equipment, MBS will help you formulate workable recipes for your situation. If you are not an Aeromaster user, MBS will formulate recipes based upon available feedstocks for a fee.


What do I need to know about moisture levels in compost?

  • Research has shown that ideal moisture levels for windrows are in the 50% range (by weight).
  • Aeromaster turners aid moisture management by permitting each particle to be watered as it passes above the drum. The compost environment is consistent throughout the row with this mechanism, as opposed to merely spraying the outside of a row, then turning. The latter method ensures “mud here” and “dust there.”
  • Fresh water needs to be used (chlorinated kills the beneficial bacteria). Effluents can be used during the thermophilic (high heat) phase of the composting process, but as the time for the heat cycle to subside occurs, fresh water is necessary.
  • Too much moisture resists turning, will cause “balling up” or clods to develop and pore spaces to be closed (causing anaerobic conditions), lowers temperature levels, and sulfides may be found in the compost (due to the anaerobic conditions).
  • Too little moisture reduces the activity of beneficial microbes, causes temperatures to rise too high, humus development is retarded, and undesirable molds may grow in the compost.

Can salt levels be managed or reduced by composting?

Yes. One of our Nevada composters saw sodium readings in a pasture drop from 799 parts per million (ppm) to 53 ppm after application of his ACS compost. Base saturation percentage sodium dropped from over 29 percent to below 3 percent during a six month period.

Humification allows the effective transformation of salt ions in manure and other compost feedstocks into a benign substance. If the composter gets the windrow into an “active carbon” phase, which includes both the thermophilic (carbon reacting with nitrogen) and the biological activity of the beneficial microlife (introduced through inoculation), he will be able to succeed in transforming or binding salt ions.

If the composter fails to do this, the salt situation actually worsens, because a 50% volume reduction doubles the problem. Microbe degradation will take the electron of the salt and pull it into a carbon chain, neutralizing and transforming part of the electron. Part of the salt will be converted into fulvic acid — an energy force for plants. Mixing 5-10% clay, which is the foundation for the humus crumb, into the windrow can help with this process.


Can composting be combined or integrated in some way with a digester, or will digesting kill all the microbial life?

Yes, it can. A “digester” (for those who don’t know) is a facility that takes raw organic matter and sics microbes on it to “digest” it, i.e. break it down, much like the first phase of composting. We would expect digestion to actually add to the microbial life, but with anaerobic microbes since it is primarly an anaerobic process.

Using that result as a feedstock into our aerobic composting process would expand the aerobic microbes and convert the material from an anaerobic state to an aerobic state.

So yes, the processes can work together without killing microbes. Their numbers simply shift as aerobic microbes replace the anaerobic ones from the digester.


I read somewhere that applying compost tea right AFTER harvest can be beneficial to the soil… is this true?

Yes, it is true! You can read all about it here.>>


How does using manure from pigs that are given Ivomec dewormer affect my compost?

Disease control demands strict adherence to clean operating procedures while composting. It is also necessary to understand air, temperature, and moisture management for each individual particle. First, every particle should be separated so no large masses of feedstock are present. Air exchange must take place so that CO2 can be released, and the compost must reach and maintain a temperature of 130-150° F. In addition, moisture levels must be monitored and sustained at 40 to 50 percent. When making humus, the appropriate ingredients should be mixed with the waste and the correct inoculants should be added.