Humanure -- Safe Use

Human waste is a complete fertiliser -- it contains the nitrogen, phosphorus and potassium that our food contained, returned to the ground it came from. For thousands of years, societies across Asia and Europe used it to maintain soil fertility. The issue is pathogen safety, not the principle.

A simple wooden compost toilet or bucket system works well. The essentials:

• A seat over a removable bucket or directly over a vault below.
• A supply of carbon cover material beside the toilet (dried leaves, bracken, or straw).
• Cover every deposit immediately with a generous handful of carbon material -- controls smell and flies within seconds.
• Empty buckets regularly (every few days for a family) into the dedicated humanure compost chamber.
• Separate urine if possible -- dramatically reduces the pathogen challenge and produces a clean, near-sterile liquid fertiliser.

Without sawdust, which needs power tools, this climate offers plenty of alternatives:

• Dried bracken fern -- best overall substitute, cut/dry in late summer, stores well, very effective odour control.
• Wood ash -- partially suppresses pathogens, adds potassium, historically the most universal amendment, use freely.
• Oat or wheat straw -- widely available, chop with a spade to improve coverage.
• Dried rushes or sedges -- cut from wetland margins, dry before use.
• Dried autumn leaves -- gather and store in autumn for year-round use.
• Peat -- effective but a finite resource, use sparingly if at all.

• Dedicated chamber -- separate from general garden compost for the full processing period.
• Build heap mass -- minimum one cubic metre; larger heaps generate more internal heat and maintain it longer.
• Insulate thoroughly -- straw bales, old carpet, or wooden boards against all sides.
• Add animal manure if available -- mixing with cattle/horse manure provides microbial diversity and additional heat.
• Twelve months filling, twelve months resting -- the two-chamber cycle applied strictly; no new additions to the resting chamber.
• Monitor for heat -- push your hand into the heap; it should feel warm to hot in the centre throughout summer. A compost thermometer is a worthwhile investment.
• Turn twice during the rest year -- to expose all material to the high-temperature core.

• Fruit trees and established shrubs -- the safest application, surface mulch only, edible parts never contact the soil, apply freely.
• Autumn dig-in for following year's brassicas -- fully composted material dug in during autumn for planting the following late spring gives maximum additional safety time.
• Avoid entirely: salad crops, root vegetables, strawberries, any crop where the edible part contacts the soil or compost directly.

Fresh urine from a healthy person is essentially sterile and an excellent nitrogen-rich fertiliser (urea, potassium, phosphorus). Treat it entirely separately from faecal composting:

• Dilute 10 parts water to 1 part urine before applying to soil or plants.
• Apply directly to the compost heap as an activator -- especially valuable in winter when the heap is cold and needs a nitrogen boost.
• Apply diluted to fruit trees and established plants in spring for a rapid nitrogen boost.
• Best applied to soil rather than direct on leaves; water in after application.