Humanure

By Hayley White

Reading time: 13 minutes

How would you feel if I told you that your waste - poop and pee specifically - could be composted and used as fertiliser for trees and plants?

I imagine you would be flipping through a whole range of emotions, some of which might include disbelief and probably a little bit of disgust. Yeah, I felt that, too. But despite what we think, many countries and cultures all around the world use composted human manure as a part of their agriculture and farming systems, and it is definitely not all negative.

Alayna Houde spent a month living in Punta Mona, a holistic living educational centre on the coast of the Caribbean. While not necessarily an expert on the science behind it, she always knew she wanted to have a composting toilet to produce her own human manure or ‘humanure’ as some people call it. But it was not until she and her husband got to Punta Mona that they really learned how to do it.

 

By Hayley White

Reading time: 13 minutes

How would you feel if I told you that your waste – poop and pee specifically – could be composted and used as fertiliser for trees and plants?

I imagine you would be flipping through a whole range of emotions, some of which might include disbelief and probably a little bit of disgust. Yeah, I felt that, too. But despite what we think, many countries and cultures all around the world use composted human manure as a part of their agriculture and farming systems, and it is definitely not all negative.

Alayna Houde

Alayna Houde spent a month living in Punta Mona, a holistic living educational centre on the coast of the Caribbean. While not necessarily an expert on the science behind it, she always knew she wanted to have a composting toilet to produce her own human manure or ‘humanure’ as some people call it. But it was not until she and her husband got to Punta Mona that they really learned how to do it.

“[Human composting] is basically a process of taking human waste and allowing beneficial bacteria to break it down into a nutrient-rich fertiliser that you can add back into the soil to heal the earth and complete the cycle instead of breaking the cycle and flushing our waste,” Alayna says. This is usually achieved by using a composting toilet which may be an expensive commercial device or a homemade job in which waste is collected in buckets. The waste is transferred to compost piles or bins where it is mixed with sawdust, grass clippings, kitchen waste, newspaper, and other compostable material.

 

For composting toilets to work well, no chemicals should be flushed or used for cleaning so that the human waste can break down naturally. They need very little water to flush and for some designs, water is not needed at all. If used properly modern composting toilets are odourless and the collecting drawers only need to be emptied every three months or so – by then the human waste has already transformed into dirt-like compostable matter and will have decreased in volume considerably.

These days, Westernised countries have strict wastewater systems that dispose of our waste for us. We do not really have to think about where it all goes, and I imagine for most of us, the last thing on our mind when we are on the dunny is the environment. These wastewater systems have special treatment plants that work towards decontaminating our waste. Though there is leftover sewerage sludge called biosolids, not all countries who produce this use it for agriculture. But some do, and they have been using biosolids or humanure for centuries.

Known as ‘night soil’ to some, sewerage was used as a fairly common ground fertiliser, especially in the ancient world. Ancient Attica collected theirs in a large reservoir that channelled into the Cephissus river valley to be used as fertiliser. Various Mesopotamian countries used human waste as fertiliser for their crops as well. The Aztecs, particularly, are well known for their chinampas. These were essentially compost islands that consisted of mud, sediment, human waste, and dead vegetation that produced crops that could be harvested up to seven times a year. Research placed the origins of the chinampas to around 1100 C.E. in an Aztec town called Culhuacan. Chinampas were constructed by fencing an area around 30 m x 2.5 m and 91 m x 9 m using wattle then filled with all the things mentioned above. Trees were planted at every corner to stabilise the chinampas, primarily āhuexōtl (Mexican willow tree) and āhuēhuētl (Montezuma bald cypress tree). Chinampas were quite common before the Spanish conquest and can sometimes be seen today in Mexico.

The reuse of human waste as fertiliser was common in Japan as well. In the city of Edo, compost farmers used to gather night soil to sell to farmers – a good additional income for both farmers and the apartment owners from whom it was gathered. Human waste from higher classes was sold at higher prices because their diets were better, so presumably more nutrients lay in their waste. After World War II, selling human waste became less common, both for sanitary reasons and because of the introduction of chemical fertilisers, and only 1% of night soil was used. This was also the result of the American occupying force in Japan at the time who did not agree with the use of night soil and considered it unhygienic. They condemned the practice and tried to stop people from eating fruits and vegetables from local markets who still used night soil as fertiliser.

And those sanitary concerns were not unfounded. Nowadays, there has been a ton of research into creating safe ways to compost human waste – and composting toilets are a big part of that. But for most developing countries attempting the technique, the biggest struggle is combatting the parasites and diseases transferred from untreated human waste. It is an important point to make: if human composting for the reuse of human waste is not done properly, there can be issues.

“I don’t know down to the science exactly what the reasoning is for all of that, but I do know that they said it’s usually safer to put it on things like larger trees. But I do think that it can be used for food crops if it’s properly managed and in a healthy ecosystem that can handle the bacteria balances,” says Alayna. To be fair, no one else really knows the science either, because it seems that little research has been undertaken although there are a ton of YouTube videos on the subject. Some people believe that humanure should not be used on crops destined for human consumption.

Alayna got to see how it’s done first-hand in Costa Rica. “So, it was when we got [to Costa Rica] that they first showed us their system. We were there for a month, so we got to know the system pretty well. Basically, they have a large wooden structure that sits off the ground and you go up the stairs to get into the bathroom stalls and it kind of drops down into a large pit beneath – which is why it’s built off the ground a little bit,” she explains to me.

“They instruct you to use it normally and then you put a few scoops of the sawdust and wood chippings they collect after they’re done cutting wood in on top of your waste, and that’s pretty much all there is to our side of using it.”

She says that they were told to pee outside in nature because the nitrogen level in urine usually makes it smell bad. But Alayna says that once their stall pits are full, they let them sit for around three to six months to fully break down, depending on the number of people who regularly use one particular composting toilet. She says that sometimes the stalls are needed before then, so they move the pit into a field and leave it for a few months to decompose.

The amount of time needed for human waste to decompose varies. Alayna says that it takes three to six months in Costa Rica because it is so hot, but in other countries, it can take anywhere up to a year. The system is pretty lengthy but mixing in other compostable materials like mulch and sawdust, can increase the temperature of the compost and speed up the process.

Of course, not everyone would be open to the idea of sewerage sludge or human compost being used to fertilise their gardens – and each to their own choice. But whether human composting should be a household occurrence, Alayna says there were a few people who expressed concerns when she posted her video on social media.

“When I posted my Reel [on Instagram] people got a little bit upset thinking that it would be a problem, so I think it’s important people are educated to know how it’s done and how the environment can properly break it down. I think that a lot of people with homesteads are already incorporating compost toilet systems into their property. That lowers their need for water because using fresh water to flush waste can be avoided which is amazing and then getting that fertiliser for the earth is also amazing. I think it would be beneficial to do that as long as it’s done properly,” she says to me.

There have also been several studies into whether human waste is beneficial for the environment and, surprise, surprise; it is! Nitrogen is one of the most important elements needed for plant growth, and human waste has it in abundance. A study conducted by Park, Cho, Choi, and Ligaray (2019) showed that using human waste in composting is an effective nutrient source, not only because of the nitrogen but also the humic and fulvic acids that are found there too. The interesting distinction in this study was that human manure derived from a purely organic diet was much better than regular manure, but either one was a great source of nutrients for germination.

For Alayna, the benefits of using human waste as a part of fertilising gardens closes the environmental loop. For her, this means that when we take from the earth, we also give back and return all those nutrients to the soil.

“If you look at monoculture, we see their fields are dusty and depleted of nutrients because we take; we don’t give back. So, I think the biggest thing about humanure is the concept of being part of the cycle of nature; taking food from nature; eating it; decomposing it the way our bodies do and then giving it back to nature so that the plants that need nutrients can take it back up and use it again,” she tells me.

“So, I think when we’re putting it into septic systems, we’re kind of removing ourselves from the cycle of nature. I think the best way to heal our planet is to put ourselves back into that cycle and say we are a part of nature – not separate; and when we work with nature, I think we can heal our planet.”

 

Source: Organic matter composition of manure and its potential impact on plant growth. Sustainability

To immerse yourself in more articles like this, Subscribe or Log in