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  • Perry Haldenby

Creating Thermophilic Compost


In part 1 my Soil Food Web consultant training, I'll be evaluated on creating compost adhering to specific high standards. This involves using carefully chosen organic materials, meeting processing time frames and reaching prescribed heat temperatures in the pile to eliminate pathogens and weed seeds. Additionally, using the microscope, I'll assess the compost pile to ensure it meets Dr. Elaine Ingham's criteria for the minimum amount of soil biology per gram of soil.


As I'm going through this process of experimentation, I thought it would be good idea to document the whole process and share my trials for us all to learn.


In this first post, I will describe the process of creating a thermophilic compost pile (hot composting). In subsequent posts, I will share how the composting process unfolded, highlighting significant variables such as time frames, number of pile turns for aeration, and the temperature and moisture levels of the pile. If you create your own thermophilic compost piles, you will also need to consider these same variables. There is an art and a science to this method.


Why do we want to create compost in the first place?

Compost is a nutrient-rich, organic material that is produced through the decomposition of organic waste. It is a natural and environmentally friendly way to recycle kitchen and garden waste, turning it into a valuable soil amendment. Composting is a controlled process that involves the breakdown of organic matter by microorganisms such as bacteria, fungi, and other decomposers.


One of the most crucial reasons why we want to create compost is to grow a multitude and diverse population of soil micro-organisms. In order to grow a diverse population of microorganisms, we need to create a system that feeds the organisms with a diverse array of food, in the compost industry, this food is often referred to as 'starting materials'. Remember, there are about 1 billion organisms in 1 gram of soil.


The basic ingredients (starting materials) for hot composting include


1. Green materials: These are nitrogen-rich materials, often referred to as "greens," and include things like kitchen scraps (fruit and vegetable peels, coffee grounds), fresh garden waste (lawn clippings). Green materials are predominately broken down by 'bacteria' due to the simple sugar structure of plant materials. Bacteria have trouble breaking down complex carbon structures like wood chip (brown materials) because they cannot produce the enzymes needed. Bacteria multiply on average every 20 minutes, and thus they create heat rapidly and then sustain the heat.


2. Brown materials: These are carbon-rich materials, known as "browns," and include materials like wood chips, dried leaves, straw, shredded newspaper, and shredded cardboard. Its the fungi's role to breakdown these complex carbon structures, they are successful at this because they can produce many enzymes at the same time, bacteria on the other hand only produce one enzyme at a time, so are less efficient at breaking down brown materials then fungi. Fungi multiply on average every 3 hours.


3.High nitrogen materials: Include farm animal manures, alfalfa, spent beer mash, grains, and seeds. Personally, I opt not to use animal manures due to the higher risk of pathogen contamination, also aligning to veganic farming practices, also known as 'stockfree' farming. Bacteria break down these materials rapidly, multiplying and generating heat quickly, providing the compost pile with an initial boost of heat.


4. Water: Adequate moisture is essential for the composting process. The compost pile should be kept moist but not waterlogged. About 50% moisture levels. Remember that microbes need water water to stay alive, just like us humans.


5. Air: Proper aeration is crucial for the microbes involved in aerobic decomposition.


The decomposition process in composting involves the activity of bacteria, fungi, and other microorganisms that break down organic materials into simpler substances.


Composting offers several benefits:


1. Waste Reduction: Composting diverts organic waste from landfills, reducing the volume of trash and preventing the release of greenhouse gases produced during the decomposition of organic matter in landfills.


2. Biological inputs: If made correctly, compost will 'grow' a diverse multitude of microorganisms, such as bacteria, fungus, protozoa and nematodes, which are crucial in aiding nutrient cycling, building soil structure, along with protecting plants from pests and disease.


3. Water Conservation: Compost improves soil water retention, reducing the need for frequent irrigation.


4. Sustainable Gardening: Using biological rich compost in gardening negates the need for chemical fertilisers and supports sustainable agricultural practices. Chemical fertilisers are detrimental for they kill the very microorganisms that we need in order to create our effective living systems.


With that understanding, below I will walk you through my thermophilic compost pile preparation, including all the materials and tools I used.


Materials and tools I used to build my compost pile included:


  • 1 Reused wooden pallet

  • 12ft wire meshing to create a 'cage' to hold the starting materials.

  • Chicken wire, to use on the base of the pallet to prevent starting materials falling through the gaps.

  • 3 Bungee cables to help hold the cage in place.

  • Pliers to to help cut the wire meshing and chicken wire.

  • The volume of starting materials used to create the compost pile was 800L.

  • The 800L was divided into:

  • 1 Compost specific thermometer to record pile temperatures.

  • 1 Tarpaulin to use as a cover for the finished compost pile.



Step 1. The pallet


















This is a standard sized wooden pallet. Its approximately 3ft by 4ft. I try not to use any colour painted pallets to avoid toxins.


The pallet serves as the base for the compost pile. While it's not essential, using a pallet offers several benefits. It creates a space for air flow underneath, ensuring the pile remains well-oxygenated.


Additionally, elevating the compost pile off the ground is advantageous. This prevents potential issues such as water logging during heavy rain. By being raised, the pile is safeguarded from washing away and avoids becoming saturated with water, which could lead to anaerobic conditions due to the lack of air spaces occupied by the water



Step 2. Covering the pallet


















Adding the chicken wire to the base of the wooden pallet helps prevent the starting materials falling through the gaps of the pallet. I bought this chicken wire from my local hardware store, it was quite cheap and was bought in a roll. I measured the wire to fit the whole base of the wooden pallet. In order to save using resources, I didn't use any nails or plastic zip ties to hold it place, I simply tucked the ends underneath the pallet to secure it in place.



Step3. Preparing the cage























To prepare the wire cage encapsulating the starting material and creating a structured pile, I utilised a cylindrical form. This design facilitates systematic heating and oxygenation through a specific turning sequence, which I will detail later.


The images below show the tools used in constructing the wire cage. Using a wire frame with 1-inch squares, I cut a 12ft length from a roll approximately 3ft in height. This sizing allowed for a cylindrical wire frame capable of holding 800 litres of starting material.


Wire cutters were used to shape the frame, and it was secured with three bungee cords – one at the top, one in the centre and one at the bottom.


The cage will be used over and over again for future compost piles.


Wire cutters being used. Red bungee cord, used to hold cages shape.


Step 4. Preparing the recipe buckets

I used the 'bucket method' as described by Dr. Elaine Ingham for this composting experiment, this ensures precise and easy to use measurements of the materials used. This meticulous recording is crucial for monitoring and documenting the experiment. Successful outcomes provide valuable notes and measurements, enabling the replication of the experiment with the expectation of achieving consistent results.


I used 30 litre buckets to measure my ingredients.


I was gifted these reclaimed buckets which I was really grateful for, alternatively you can likely buy them for around £1 to £2 pounds each on sites like facebook market place, its often builders that sell them on after using them for cement bags.


To calculate how many buckets needed for a 800 litre compost pile, simply divide 800/30 = 26.6 ( I rounded up to 27)


Sometimes the buckets being sold are 20 litres in size, this is totally fine to use, just adjust the math to work out how many you need, 800/20 = 40 buckets.


In order to save space or money buying 30/40 buckets, you can use 10 buckets, emptying and refilling them until you reach the desired amount. For ease and efficiency I used and filled the exact amount of buckets that I needed.


Below, the picture on the left, you can see my buckets set out ready to be filled with my starting materials. The picture on the right are my buckets filled with the various starting materials, ready to be soon mixed together and placed into the wire frame.



Working out the percentages of starting materials to fill your buckets


There are many considerations when it comes to creating recipes for thermophilic composting. Remember, we are balancing Nitrogen (green materials) with Carbon (brown materials) and we are inserting a little High Nitrogen to create a boost of heat.


Note: Heat in a compost pile the is created by the microorganisms rapidly reproducing.


We also have to consider the ambient temperature (outside temperatures) of your location, you can check this using an app or checking online.


For my compost pile I used 27 buckets at 30 litres each


60% Wood chips (carbon source) = 16 buckets

30% Grass clippings (Nitrogen source) = 8 buckets

10% Spent beer mash (High nitrogen source) = 3 buckets


The ambient temperatures in my region were a high of 13C (55.4F) and a low of 7C (44.6F). It was November in the U.K.


If ambient temperatures are colder, then we would slightly increase the amount of nitrogen and decrease the amount of carbon, and perhaps create a bigger pile to create more thermal mass. The extra nitrogen brings extra heat.





















Wood chip




















Grass clippings




















Beer Mash


Step 5. Mixing the ingredients together

Use a tarp as a mixing surface near your wire frame. Place 1/3 of each material on the tarp. For my materials that meant firstly mixing:

5.3 buckets of wood chips.

2.6 buckets of grass clippings.

1 bucket of beer mash.

Then mix thoroughly.



After the materials are mixed together, place the whole mixture into the base of the wire cage.





















Next

Repeat step 5, mixing another 1/3 of your starting materials and placing it into the cage.





















Add the last third of your starting materials until the wire cage is nearly full to the top. Ensure all buckets are now empty, and the starting materials are well-mixed inside the wire cage, ready for decomposition. To maintain the pile's shape, I've used bungee cables, and it sits neatly on the wooden pallet, facilitating airflow



Finally


At this point, the compost is ready for activation, and within the initial 24 hours, a notable rise in temperatures should become evident. Before leaving the pile unattended, a crucial step remains—to 'cover' it with a tarp. This precautionary measure serves to shield the compost from adverse weather conditions, preventing potential issues such as water logging due to excessive rain or snow, as well as dehydration from prolonged exposure to wind and sunlight


Simply secure a tarp over the top of the pile and leave about a 1 to 2ft gap around the bottom to allow for air flow. I used bungee cables to secure the tarp in place. See the picture below.





















Measuring and monitoring

With the construction of the compost pile completed, we are now employing measuring tools record the experiment and to comply with organic safety regulations.


Three variables are measured and recorded for the purpose of gaining a thorough understanding of the starting materials used. This observational approach allows us to learn how these materials interact with each other. The recorded results serve as a valuable resource, enabling us to replicate successful outcomes and refine aspects that may not have yielded the desired results in our experimentation.


The variables that we measure are:

  • Time

  • Temperature (Ambient temperature and Compost pile temperature)

  • Moisture (Moisture inside the pile)


What next?

In terms of 'building' the initial thermophilic compost pile, that is all the information you need. The instructions above will help you create and good standard thermophilic compost pile.


So how did my compost pile turn out?

In an upcoming post, which I'll be sharing shortly, I'll delve into the outcomes of my composting experiment. I'll provide detailed insights by sharing the measurements and recordings I documented, including dates, times, ambient temperatures, pile temperatures, and moisture levels. Stay tuned for a comprehensive overview of the experiment's results.


Summary and key learning

In this post, we've explored how composting transforms organic waste into nutrient-rich soil teeming with diverse microorganisms.


I cant emphasis enough how crucial it is to recognise that microorganisms play vital roles in nutrient cycling, soil structure, and defence systems against pests and diseases. Its essential for these organisms to be living in our soils.


I also shared step by step instructions on how to set up your very own thermophilic compost pile (hot composting).


Understanding that heat is generated in the decomposition process, and that the pile will need to be kept aerated as the microorganisms that we are interested in growing thrive in aerobic environments.


Time, heat, moisture and air are key components in achieving a biological rich living compost.


I hope the post was clear and helpful, giving you the tools and steps to create your own compost pile. Please don't hesitate to reach out if you have any further questions.


Dont forget I will be shortly sharing the results of my trial compost heap, along with the recordings of the key variables.


All the services I offer, along with the information I share, are provided free of charge. However, if you'd like to contribute, your donation would be greatly appreciated. Donations help support the creation of more content and the biological soil lab services I offer. You can find out more about donations on my page here


If you would like to find out more about the soil assessment services I offer please click here,

and to learn more how I assess soil samples, please consider reading my previous post here


Let me know how you get on!


Perry



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