Unlike green manure, humanure is actual excrement. As the clever name might lead you to guess, it is excrement that comes from humans. What does this have to do with natural gardening?
Let’s talk about fertilizer.
Fertilizer is substances – often artificial substances – that help to provide nutrients for plants. A key ingredient in fertilizer is nitrogen, an element that is important to both plants and animals. Nitrogen is found abundantly in our atmosphere – when you breathe, you are inhaling much more nitrogen than oxygen. But most plants cannot absorb nitrogen from the air. They need it in a different form.
This alternative form can be artificial fertilizer, or it can be compost. To make good compost, we must put in materials that contain lots of nitrogen. What contains lots of nitrogen? One answer is (recently) dead plants. Another answer is human waste.
Our own urine and excrement – which to us is useless and toxic – is valuable and nourishing to plants. If we relieve ourselves on plants, they will happily absorb that nitrogen.
While it might be fine to do exactly that on a camping trip in the woods, nobody thinks we should fertilize our suburban yards by defecating in them. Instead, we can use the somewhat more refined process called humanure.
We begin with a composting toilet. This device, instead of using clean, drinkable water to move our bodily waste to a treatment center, simply collects our byproducts in a bucket. A seat can be placed on top of the bucket to make it more comfortable, and a handful of sawdust after every use will hide the mess and absorb all the odors.
When the bucket is full, it can be emptied into a compost pile. At this point, it is very important that the compost be managed well. Human waste is full of pathogens, and the compost pile must get hot enough to kill those organisms. (No need for artificial heat: the beneficial organisms in the pile will generate plenty of warmth as they munch their way through all that delicious organic matter.)
Once the humanure is fully decomposed, it is indistinguishable from any other finished compost, and it is safe to use on our plants – even on our vegetable gardens. However, like greywater systems, humanure is severely frowned upon by many local health departments, due to its perceived hazards.
Humanure is a normal and natural way of recycling waste products back into valuable resources. It connects our own bodily processes to the cycles of the earth. However, because it is dangerous if not managed properly, and because it is not yet legal in many places, please thoroughly educate yourself on this topic before attempting to establish a humanure system. There is no shame in planting some native flowers today, and leaving humanure until you are more experienced and confident as a natural gardener.