Humanure

Humanure, simply put, is the composted excrement produced by humans.

The word composted here is important because when working with humanure we need to make sure that human pathogens that may be present in the excreta are rendered harmless to produce safe and nutritious compost soil that can be used for food production.

In the Humanure Handbook by Joseph Jenkins in Chapter 5 you will find that organic compostable material is theming with mesophilic and thermophilic bacteria which will help raise the temperature of the compost pile to levels which destroy human pathogens ie above 60 degrees Celsius.

<to do insert table for temperature to time destruction of common pathogens and parasites here>

This is an important stage in composting. If the compostable material is not composting ie reaching required temperatures then the material is not safe to be used as fertilizer on the ground.

Joseph Jenkins outlines the composting stages as follows:

1. Mesophilic Phase > temperatures up to 44 degrees Celsius
2. Thermophilic Phase > temperatures up to 70 degrees Celsius or higher
3. Cooling > temperatures decreasing slowly
4. Curing > temperatures stable and going to outdoor air temperatures

For composting to happen micro-organisms have to be able to travel around the compostable materials to break it down, this is not possible without moisture.

If urine is separated you will need to add moisture to the compostable material in order to start the composting process. The material needs to be moist but not water logged or oversaturated/leaking. A water logged compostable pile will stink and the odor will be an indicator that you need to add more dry organic matter such as sawdust which absorbs the moisture and acts as a biofilter for odors. This is not only documented in many composting books including: <to do insert references here>, you can ask any compost toilet owner and they will confirm this. Straw is a less efficient biofilter but a good top cover - on top of the compostable pile where you want to discourage animals from digging through it.

If urine is not separated you will need more sawdust per toilet use this is because of the odor produced by urine. However, with the right amount of sawdust to excreta (let your nose guide you) you will have an odorless toilet.

At Kuckucksmühle we have two mobile compost toilets in order to make the most of the humanure we produce we want to research and document our findings here together with any test results.

In the first year of use, 2018 we separated the urine in a big water tank, we diluted the urine with water 10 to 1 and watered the garden with it. Unfortunately the moisture content in the compostable pile pile was not enough to complete the composting process at least in the outside areas of the pile. One can still see solid perfectly shaped poop. So what happened?

1. Rain water was not enough to provide the required moisture levels in the compostable pile
2. The outside insulation layer (thin straw layer) may not have been enough to reach the thermophilic stage in the edges of the pile
3. Ants moved into the pile which is a strong indicator that the pile was too dry and not nearly warm enough

This means that the compostable material has to be:

1. Reinsulated with straw / other organic material
2. Rehydrated - we are discussing whether to use urine from the tank for this purpose
3. Monitoring of temperatures and moisture to establish where we are in the composting stage

An immediate action was the purchase a compost thermometer (July 2019).

In order to ensure that the humanure is composting properly we need to monitor the temperatures of the pile, this will tell us whether the pile is reaching high enough temperatures to destroy any pathogens that may be present in the pile. It also gives us the opportunity to correct conditions in the pile in order to reach and maintain the right conditions for compostation to happen.

Important factors to consider:

• if the pile is too dry the temperature is likely to drop as the compostation process slows down
• if there are ants this is an indication that the pile is too dry and too cool to put them off

The solution would be to add water in the middle of the compost and cover top with straw

• the addition of water/liquid should be gradual to avoid waterlogged conditions which would cause the pile to stink

The solution would be to add more dry material but as the pile is full we should avoid going to this stage, add water/liquid slowly and monitor temperatures daily.

Observations should include ambient temperature spikes, rain and previous day weather conditions, changes to the compost pile like addition of water or dry material should be documented, together with temperature changes.