Life, Poop, and Compost

Our New Orleans Compost Bioreactor Journey

Written by Nat Kearney

Bioreactor Composting System built and ready to be filled.

On February 1st, 2024 at Baby T-Rex Farms in Mid-City, New Orleans, four sweaty, smiley, and poop-stained people gathered together to enjoy lunch after successfully filling a homemade, six foot tall cylindrical structure with an assortment of scavenged composting materials.

To understand how we arrived at this scene, we have to go back several months to July 2023. Megan, the founder and farmer behind Baby T-Rex Farms, had approached me several months into my flower farming apprenticeship about the possibility of starting to research how this special kind of compost pile, called the Johnson-Su Bioreactor, functions - and if it would be a possibility to sustain one in our hot and humid New Orleans climate. To begin my research, she suggested I read the book What Your Food Ate: How to Heal Our Land and Reclaim Our Health by David R. Montgomery and Anne Biklé. In it, the authors outline a handful of radically innovative techniques that have been developed to promote diverse and healthy soil that organic plants can thrive in. One of these techniques was the Johnson-Su Bioreactor, named after its developers Dr. David Johnson and Hui-Chun Su Johnson.

Using bricks to set up the foundation for the Bioreactor Composting System

Reading the book, I began to learn that unlike traditional compost piles, which need to be regularly turned (laboriously by hand or expensively by specialist equipment), the Johnson-Su Bioreactor is an entirely aerated (therefore aerobic) composting system, so it doesn’t need to be turned. This is accomplished due to the addition of perforated tubing throughout the compost structure. (Without this addition, an unturned compost pile can quickly descend into an anaerobic environment which yields the bad kind of bacteria, like mold on rotting food.) Furthermore, the book detailed how creating one of these Johnson-Su bioreactors results in a biologically diverse, fungal-dominated compost which is proven to improve soil health. I was inspired and ready to get to work adapting the structure to thrive in a New Orleans urban environment, and got to planning with Megan about where we would source our key ingredient: poop.

A Water Buffalo from Bayou Sarah Farms in St. Francisville, Louisiana

Calling upon Megan’s extensive network of cool farmer friends, just one month later myself, Megan, Baby T-Rex prodigy Caroline, and globetrotting WWOOFER Ash were piling into Megan’s big blue pickup truck and heading to St. Francisville, Louisiana to meet Sarah of Bayou Sarah Farms. Sarah has an incredibly beautiful and only slightly scary herd of water buffalo that she lovingly raises, providing a source of organic, local meat and dairy products along the way. Her herd also provides an invaluable asset in the form of soil regeneration, utilizing a grid system to evenly graze across her land and deposit some nutrient-dense manure in the process. This manure is what we were traveling for. Sarah equipped us all with shovels and took us for a ride to a grid of her farm with the Goldilocks selection of poop: not too dry and not too wet. After collecting, we got to have some fun riding the water buffalo, touring her land, and trying some delicious water buffalo milk ice cream.

Water Buffalo Poop - a key ingredient for the Bioreactor Composting System

Once back home in New Orleans, the task turned to drying out the manure and procuring the other materials we would need for assemblage. We gathered the necessary building materials second-hand wherever we could: wire, pipes, and a pallet were all collected from The Green Project in the St. Roch neighborhood and hauled back to the farm. These materials were the bones of what would become a six-foot-tall compost bioreactor. We collected chicken manure from another friend of Megan’s, picked up some dried wood chips from Schmelly’s Dirt Farm, and collected various other yard waste materials like dried leaves from our own productive Baby T-Rex inventory.

Drilling holes PVC Pipes for aeration. PVC pipes are sourced from The Green Project

The plan was to dry all the materials by laying them out like a bizarre tapestry under the sun, and then after a few short weeks, building would commence. However, due to an unusually wet Autumn and Winter, the transition from collection to construction took longer than anticipated: waiting for poop to dry in wet New Orleans weather is not the most fruitful task, and the building plans unfortunately kept getting pushed back. In early Spring of 2024, enter Juan and Lydia, two WWOOFERs from Detroit, who brought the readiness and enthusiasm to get this project completed right when we needed it most. They successfully assembled the six foot tall structure in just a day.

Bioreactor materials laid out to dry in the sun

And just like that, the stage was set for filling. The process of filling a bioreactor is definitely a humbling one. We packed plastic crates full of filling materials (leaves, grass, mulch, poop, or some combination of all the above) and dunked them in a wheelbarrow of water, sufficiently wetting them to be packed in the reactor structure. We then hauled the crates across the garden to the reactor, up one of the two ladders propped against it, and dumped all the contents. Along with this slurry of potential life, we added pipes perforated with holes at equal distances allowing the even distribution of air throughout the whole structure. Nothing can compare to the feeling of satisfaction of climbing up the ladder and looking into the tower’s opening to dump more materials, only to realize that we had finally done it: it was full, and after only a few short hours! We successfully filled the interior of the bioreactor with this poop mixture - our soggy clothes a testament to this feat - and now we were free to change and enjoy a communal post-build meal.

Filling the Bioreactor

Not only was there the gratification of a hard day’s manual labor successfully completed, but the knowledge that we had set the stage and created the conditions for a thriving microorganism environment. Once all the materials were combined into the cylindrical reactor structure, the thermodynamic process of breakdown began, setting the stage for a slow metamorphosis over the course of a year. By leaving the bioreactor’s contents alone for this much time, the materials will dramatically shrink down, metamorphosing into maybe 60cm of a concentrated, soil-like putty at the bottom. This end product will be microbially diverse and active compost, teeming with the good minerals and micronutrients necessary for robust plant growth. Once diluted with water, it will become what’s called a “compost tea”, an enriching elixir which will nourish our soil by introducing beneficial fungi and bacteria. We can expect some pretty extraordinary results:

• increased ability for soil to capture carbon,

• increased crop yield,

• increased soil nutrient availability, and increased soil water-retention capacity.

It will improve our seed germination and growth rates, saving money and stretching our seed supplies further.

A look inside the Bioreactor

It is worth noting that composting does not have to be as complicated as this! The classic hand turned pile works wonders as well. But as a group of people fascinated with enriching our urban environment with complex microscopic life, it was definitely an interesting and worthwhile exercise. According to the scholars that developed this system, at the end of this process we will be able to reduce our water usage by up to six times, and reduce our total composting labor time by 66%. We won’t have to turn it at all, and if we ever wanted to refill the bioreactor after this batch of compost is ready for use, we can refill it with a diverse array of compost materials. The aerated thermodynamic reaction that takes place in the bioreactor produces no odors or associated insects, and all in all our materials for the whole project cost less than $300.

At the end of the day, although our building and assemblage techniques may have been a tad homespun, the structure itself is impressive. This agrarian experiment spanned months, many under the sweltering Louisiana sun, and I for one cannot be prouder to have been a part of it. For me, this process was a testament to the fact that even in the most urban of environments, there are always opportunities for creating interesting connections to the land, and to the cycle of life and decay that sustains us.

If you’re interested in building your own bioreactor in the New Orleans area, contact Megan at babytrexfarms@gmail.com!

Thank you for reading - Nat Kearney, farm apprentice and bioreactor project coordinator.

Riding the water buffalo at Bayou Sarah Farms