Experience in Composting History

John Crockett started 'playing' with compost in 1993, working with thousands of cubic yards of horse manure and wood shavings.  The shavings are used as bedding for the horses in the barn.  An invaluable lesson that I learned was that there is more to composting than I had thought. 

This is from early in 1996, that's my Case 580K (yellow) up on the pile, and you can see a man standing down at the base of the pile.  The cloud is moisture from the hot compost when exposed to cooler air.  I guess there was about 12,000 cubic yards total at this site which I worked from 8/1993 until 1997.  I estimate that I spend about $100,000 of my time and machine time, turning compost, under the illusion that I was making a major difference, keeping it much more aerobic.

That was all part of my learning process, what I refer to as my "compost university". 

It was the fall of 1995 that I started learning about VFA's, Volatile Fatty Acids, which are byproducts of Anaerobic decomposition, what Dr. Elaine Ingham likes to call "putrefaction of organic matter".

This picture from January, 1996, shows our first experiments with forced aeration.  The little blower on the ground in line with the front wheel of the loader, was the cooling blower from my 1981 Data General CS/50 computer which I salvaged in 1990. 

Within a couple of weeks of our starting to experiment with forced aeration, we got an oxygen and CO₂ meter set and started measuring the oxygen and CO₂ levels in our compost. 

What we quickly discovered, from monitoring the oxygen and CO₂ is that the microbes can apparently very quickly consume the oxygen in a pile of compost.  Logically, a key factor is how many ACTIVE aerobic bacteria are present in the pile. 

This isn't "theory".  The chart to the right represents data that we gathered, using an oxygen meter in the pile of compost pictured above. 

In the Spring of 2004 we got a $24,500 Leica microscope and started doing the microbial assays, doing direct estimates of the total and active bacteria and fungi, we started taking our documentation to a new level. 

How much air pressure does it take to keep compost aerobic?  Manometers are used to measure air pressure at low levels.  We needed to answer that question.  During 2007 we did over 150 rate of air flow tests, so we have a significant database on how much air is needed.  How much air is needed, depends on how many oxygen consumers are present, and that depends on the feedstocks and how the compost is being managed.

We made our first manometer in February of 1996.  Being cold weather, we used automobile antifreeze for the fluid.  We quickly found that it takes less than ¼ psi of pressure.  24" difference in the columns of fluid would be 1 psi.

By Spring of 1998 our aeration manifolds and manometers had gone through a number of permutations, development stages.  This manifold was 157' long, and was attached to a diesel powered blower that we developed, and which performed up to our highest expectations, and burned only 8.2 gallons of diesel fuel a day, running full time.

this picture shows a system that we developed in the Spring of 1996.   It utilized a 1 horsepower electric blower that put out about 800 cfm.  We used a generator to provide the electric power, and the generator burned about 11 gallons of fuel per day, making it far more expensive to operate than the diesel powered blower which we developed afterwards. 

While our first diesel powered blower may have been a bit crude, the important thing is that it worked very well, and economically.  It was the culmination of three and a half years of experimenting and learning, two years of playing with forced aeration. 

I

N 1999 we started playing with compost research silos.  Again, the system shown to the left was the result of having gone through several previous versions, learning along the way.   The aeration manifold for the silos, likewise, was the result of several earlier versions.

Our compost research silos include thermocouples for monitoring temperature, connected to an Omega TempScan, which is connected to a computer in our office. 

The silos have been used for doing extensive research composting the organic residuals from a local restaurant.  During the Summer of 2000, we worked the silos quite intensively. 

Our compost research silos have been constantly going through an evolution, constantly being improved.  The picture to the right shows what they were like as of the end of August, 2006.

Much time and energy has gone into designing the new composting facility.  Moisture balancing of incoming feedstock is one important consideration.  It was during the late Fall of 2001 that we developed a good working understanding of mass / moisture balancing.

The values in the "Ratio" column are proportions by volume.  Until we test and verify this at the compost research silo level, it is good "theory".  We feel that it needs to be verified. 

In the Spring of 2001 we refined our ability to do compost moisture content testing.  We developed a simple QuattroPro Spreadsheet template, that makes it really easy to 'crunch' the numbers.  We also bought a lab balance that has a capacity of 200 grams, accurate to a hundredth of a gram. 

Basically the formula is:

We weigh the dish, add some moist compost and weigh the combination of the dish and sample.  Then we bake it for 12 hours at about 200°F, to bake out the moisture.  Then we weigh the dish with the dried compost.  Once we have that information entered in the spreadsheet, the formula in the last column determines the moisture content.   Baking in a MicroWave oven does not work well, based on our experimenting. 

Bio-Assaying, Quantifying our Microbial Workforce... "census taking"

In August of 2002 we developed a QuattroPro spreadsheet template for processing the numbers for assaying the total and active bacteria in compost and/or soil.

The data shown is from Sample #2518, assayed in our own lab on June 14^th, 2004.  Considerable mind power went into developing this template, including the key formulas.

In 2004 we invested over $24,000 in a Leica microscope, and additional funds in other lab ware, enabling us to do the assaying.

We feel that to responsibly manage large volumes of compost, we must be able to 'check up on our microbial workers'.   Doing direct estimates, using basic microbial assaying techniques seems at this point the best way to check up on our workers.

While research is expensive, it is far less expensive than ignorance.

Why are we targeting Food Residuals?

This page was last updated: March 15, 2011 10:10 PM