Human-produced fertilizer—why not? – GardenRant

Guest post by Natalie Levin

Composted manure, blood meal, bone meal, and fish emulsion are popular soil amendments. We routinely use these materials in our gardens. But consider adding your own menstrual blood or urine to your watering can and suddenly you might be a pervert. Despite this double standard, I maintain that using one’s own body fluids is safe and arguably less gross than using those of other animals. It’s also more sustainable and compatible with the idea of a garden being a peaceful place of harmony with living things.

Photo by Christine Matthews

The sacrosanct status of animal waste in gardening is a product of colonialist farming systems. Human cultures around the world have traditionally used a wide variety of materials from plants, human waste, and other animals as soil amendments. Those who domesticated large ungulates as livestock came to rely heavily on their manure, but this practice was never universal. Prior to European colonization, slash and burn or swidden agriculture was predominant in the Americas, where animal domestication was far more limited. Reliance on farmed animal byproducts as a primary fertilizer is a European tradition, enshrined in organic farming principles by the European and white American founders of the movement.^⁠

It takes for granted that domesticated animals must be at the center of any farming system, bred in large enough numbers to produce massive quantities of waste. In fact, there is no need to filter plant matter through animals to produce fertilizer. Animal agriculture is a significant emitter of greenhouse gases and the leading threat to biodiversity.⁠ There is an acute environmental need to shrink the industry, which has spawned a rise in reducetarian and plant-based dietary movements. And yet, products from animal farms, slaughterhouses, and industrial fisheries dominate the organic fertilizer market and gardening lore. When gardeners purchase these soil amendments, we are investing in an unsustainable industry. We might think that we are merely using up waste, but, in fact, the meat industry relies on marketing every part of the animal in order to remain profitable.⁠ Why cut back on hamburgers only to sprinkle cow blood on the garden?

Every garden hosts at least one animal who produces free nitrogen-rich soil amendments, and that is the gardener. Humanure is an obvious stand-in for livestock manure, but, first, you have to compost it yourself under specific conditions in order to kill off harmful pathogens.

Urine is easier and safer to use and can be poured into the soil right away, diluted with about 10 parts water. It can also be added to a compost pile to speed up decomposition of carbon-heavy brown material.^⁠ The same applies to menstrual blood. All three of these human waste products have been used in agriculture by people around the world, including in modern industrialized farming. Humans generally do not produce enough waste for it to be the primary source of agricultural fertilizer, but it can go a long way in a garden, especially when combined with composted kitchen scraps, green manures, or fallen leaves.

The gardening world is slowly moving beyond chemical fertilizer and composted manure as the go-to soil amendments. For those who have the forethought and space, compost piles are increasingly popular. Composting toilets are becoming somewhat more popular and urine fertilizer is reaching the edges of the mainstream gardening world.^⁠ It’s still considered a kooky thing to do. And when it comes to using menstrual fluids, ancient taboos persist about its supposedly negative powers.^⁠ The occasional brave TikTok hippie who shares her menstrual gardening secret is met with barfing emojis and may worry about it killing her plants or scaring away partners. Articles on the subject recount fearful experiments and concerns about the dangers of bacteria.^⁠ Those who support the practice tend to give it outsize credit as a magical elixir. But its nutritional profile is the same as slaughterhouse blood. The difference is that this is free.

In my view, it makes no sense to think that purchasing the blood and waste of farmed animals is preferable to flushing our own blood and waste down the toilet. Though, when it comes down to it, none of these amendments are necessary. You can have a lush garden using composted kitchen waste, lawn trimmings, comfrey, and other green manures. But if we’re going to use animal-based fertilizers, why not use our own? It costs nothing and wastes less. And it doesn’t contribute to the unsustainable industry that produces livestock manure, blood meal, and bone meal.