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Introduction to Humanure: Let's Talk about Poop

Building a Fertility Lab

Moving to a raw piece of land is at once thoroughly exhilarating and overwhelming. My partner and I moved to our homestead Mountain Jewel as part of our lifelong adventure, driven by a desire to embody a vibrant way of life, create something worthwhile and beautiful and be able to share the abundance and beauty of Earth centered living with others. When we moved here, there was an overgrown driveway, 15 ac +/- of mature woods and roughly 3 acres of old field full of young saplings and the plants affectionately known as “brush” that had been cleared a decade or so ago. Moving onsite full time on New Year’s Day 2016 was the biggest step of we’ve ever made.

The homestead priorities began with the humble step of meeting our daily needs. Getting water, finding ways to prepare food, setting up a shelter, and managing our outputs (the stuff that starts shitty conversations) and finding creative ways to use our outputs as inputs into another (something thought of as waste into something useable like compost). Having a lot of exposure to ecologically sound ways of living through visiting eco villages, WWOOFING, taking part in Permaculture courses and self guided study, we knew that we needed to develop a system to safely transform out humanure into rich humus (the backbone of a healthy soil food web). And so we began.

Having never built anything (we had participated in some building projects, but never as the guiding force), we thought a composting toilet would be great place to start. It would meet our needs of humanure management and allow us to experiment with different natural building techniques. We wanted a place we visited at least once a day to be peaceful, beautiful and enjoyable, so we took our time to make this project intentional.

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Humanure

We had read John Jenkins Humanure Handbook (See part 3 of this post) and were fairly familiar with our options. The simplest method is the bucket system, where 5 gallon buckets are filled with humanure, urine and sawdust and emptied into an outdoor composting bin. Having no running water, and looking into the future where we didn’t want one more chore (emptying and cleaning buckets), we opted for a double bay system in a standalone building.

Compost Chambers

We built the 2 bays from local rocks we picked up from the side of the road after grading. They we widely varied in size and shape and certainly made for an interesting process of laying and fitting rocks together. This was our first time laying stones and it was a satisfying and creative process, albeit slow & heavy. We used a lime and sand (1:3) mortar (if you do use lime, make sure it’s covered by an overhanging roof as it will erode in rain) to build the 2 stone bays. Then we created a ¼ hardware cloth dome to cover the bay and cemented it.

Foundation

We poured a small bond beam on top of the rocks to create a level surface to rest the back of the building on. We sunk 2 concrete tubes 2’ into the earth and laid stout oak posts on top to them to support the front. We had salvaged a lot of oak lumber from a friend’s barn and set to stick framing a roughly 8x8x8 cube (we designed it based on the lumber we had).

Slip Straw & Clay Plaster

Once the walls were up, we filled the cavities with slip straw / light straw clay (a little straw mixed with a clay slip and packed lightly into study cavities with a temporary form). We used local clay, sand and cow manure mixed with a little chopped straw to plaster the walls with. This is a technique we were really excited to play with as both of us had practice with straw bale, cob and using clay plaster. It took some trial and error, but after doing two more buildings in this manor, we’ve finally got the right clay ratio and density of packing (it gets its insulation or R value from actually not being packed too densely- more on this in another post).

Roof

The gable roof is a 6:12 pitch and sheathed with reclaimed corrugated galvanize steel salvaged from the same barn the studs came from. We designed a generous 2’ overhand on all side to keep water off the building. We stand by the old saying that buildings will last ages if they have a good hat (on piers and stones) and boots (roof).

In this system, one bay is used at a time to deposit urine and humanure to which aged sawdust is added (we fill up our pickup for free from a local saw mill) along with toilet paper (roles and all) and cooked chicken bones we want to keep away from dogs. The addition of carbon rich biomass is the major difference between an outhouse and composting toilet, humanure composting doesn’t stink! (If it does- add more sawdust!)

Outhouses conjure up horror stories among many of us, but this is usually because the humanure and urine are not balanced by a carbon source and thereby create an unhealthy environment and a reeking mess. The deposits are not following the natural order of things, become anaerobic and are not going through a composting process.

Composting is summed up in the acronym WONC, Water and Oxygen must best in proper balance, as must Nitrogen and Carbon.

The mass must have adequate but not excessive moisture (think of a moist sponge) and sufficient air to feed the microbes that dine on organic matter. The oxygen feeds an aerobic environment (healthy) rather than anaerobic (stinky, swamp). Ideally Carbon and Nitrogen would be in a 30:1 ratio, but composting organism are fairly forgiving. The point is striving for a balanced C and N diet.

We add sawdust to maintain the C:N ratio and absorb the liquid from our humanure and urine. Any smell is an indication that we haven’t added enough sawdust. If a humanure system smells, it’s time to add sawdust (or any other appropriate carbon source such as rice hulls, straw, leaves etc.). Don’t be shy with adding more carbon.

We happily go on filling our first bay with humanure, urine and sawdust (the soldier fly larvae invited themselves and we are happy about this! More on these guys in future posts). We fill until we can’t fill anymore. We were amazed how much the mass keeps settling as the soldier fly larvae were digesting the humanure and turning it into frass. It would literally sink inches each day and we just kept filling it up! Eventually our bay reaches capacity, and we switch over to the second bay. The fist bay filled up after more than a year of use (mostly the 2 of us).

We leave the first bay to sit while the second is in use (a sure safe time period for humanure to compost is 2 years). Once the second bay fills up, we will move the compost from the first bay to an outdoor composting bay, and let sit another year, just to be safe (some pathogens are survivalists!). Then we will top dress the numerous fruit and nut trees and shrubs we have established at Mountain Jewel. When our humanure has transformed into humus, it would be safe to add to annual garden as John Jenkins does, but we’re exercising extra caution, not to mention our perennial production is much higher than our annual beds. There are thermophilic methods (hot systems) of humanure composting that don’t need to sit two years, but that’s not the subject of this post.

We are really happy we built this composting toilet and are pleased to say it has served its purpose of providing and safe and enjoyable experience of managing humanure and teaching up about natural building. We focused on beauty and aesthetics because both of us had sat in too many shitty outdoor toilets to create one ourselves. The act of relieving oneself should be relaxing, not something you want to get away from! The was the first project of many at Mountain Jewel endeavoring to meet immediate needs, experiment, grow, learn, highlight local materials and live in line with Earth.

The next building we’ll showcase is our solar storage shed made with locally milled (cut on our property, milled on our property!) live edge cedar and slip straw with clay plaster and a rubble trench foundation with poly bags filled with stone!

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