BY NATALIE BOGWALKER AND CHLOE LIEBERMAN

Plants do not grow because we feed them. They grow because the soil feeds them.

And soil, in turn, is fed by what once lived—plants, animals, microbes, fire, decay, and the steady return of nutrients through natural cycles.

Long before synthetic fertilizers and soil tests, fertility moved in a closed loop. Animals grazed, forests burned and regrew, minerals weathered, microbes digested, and nutrients circled back into the ground. What we often label as waste—manure, even urine—is part of that ancient exchange.

In modern systems, these materials are treated as problems to dispose of rather than resources to steward. Manure becomes pollution when concentrated in the wrong place. Urine is diluted and flushed into overburdened wastewater systems.

Even carbon, released through burning and decay, is framed only as a liability. Yet in a garden, these same materials can be transformed. They become sources of nitrogen, phosphorus, potassium, calcium, carbon, and microbial life— precisely the elements plants depend on for steady growth.

To “feed what feeds you” is to consciously re-enter this cycle. It means learning how to age manure safely and even reconsidering human urine as a nutrient-rich fertilizer rather than something to discard.

Each material has its own cautions and considerations, but together they represent a powerful truth: fertility is not something we manufacture. It is something we return.

Manure Fertilizer

Poop has been used to enrich soil and feed plants since plants began growing and animals began pooping. It makes sense: Animals eat plants (or eat other animals who eat plants) and then digest the nutrients from those plants (with the help of billions of gut microorganisms), only to excrete some of those same nutrients (and the dead bodies of the microbes) back onto the earth. It’s the original closed-loop sustainable model.

Bringing manure into the garden can favorably disrupt a waste stream, too. Larger-scale animal agriculture operations end up polluting groundwater, along with creeks and streams, when manure isn’t properly managed. The nitrogen from this manure, which can be amazing for plants, feeds algae blooms that wreak havoc on stream and river biology.

It goes without saying that big piles of poop are also stinky and attract flies. The silver lining is that you can sometimes get loads of manure for free or cheaply, especially if you’re able to transport it yourself.

Using manure in the garden can be highly beneficial, and although it’s not without challenges and precautions, you can usually manage it safely for both your plants and yourself.

Plant Nutrients in Manure

Almost all manures contain mineral nutrients, including macronutrients nitrogen (N), phosphorus (P), and potassium (K), in high quantities, as well as secondary nutrients, micronutrients, organic matter, and microorganisms. Real quantities of these nutrients depend on what the animals eat, their life stage, the season, and other factors, but rough averages can be estimated.

Aging or Composting Manure

To use manure safely, it’s best to age or compost it first. This is absolutely essential with “hot manure” (high in soluble nitrogen), which should never be added fresh in a garden bed where plants will grow within three months or less, as it will burn them and/or inhibit germination.

Once it has had time to decompose and mellow, hot manure is great to use. Another way to deal with hot manure is to add it in and then wait for a few months to plant in that area. This aging or waiting period isn’t necessary for “cold manures” like rabbit, goat, and llama poop.

Tip: “Hot manures” should be aged for at least three months before being added to a garden bed. When applied fresh, they can burn plants and inhibit the germination of seeds.

Three Ways to Age Manure

1. Dig it into garden beds in fall, but don’t plant anything there until spring.

2. Build a compost pile with the manure and other inputs (like straw), and let the decomposition process break it down more actively than just letting it sit.

3. Pile up manure in a heap and let it sit, although this will result in high nitrogen loss due to surface runoff from rain.

Pro Tip 1: If you choose the low-labor approach of piling up manure and waiting, cover it with a tarp to reduce nitrogen loss.

Pro Tip 2: If you get manure from a farm, ask the farmer how old the manure is and if it has been actively composted or aged—often it already has.

How to Apply Manure

Once the manure is ready, you can either work it into a bed or use it as a side dressing for established plants. Either way, cover the manure with soil and/or mulch so the sun’s heat doesn’t denitrify it (transform its nitrogen from plant-available forms back into airborne forms).

Sometimes we use soiled animal bedding (such as straw or wood shavings that are coated in manure) as mulch. Some of the nitrogen will be lost to the wind, and some will wash into the soil during rainfall and/ or when we water. This is a reasonable trade-off, however, since separating manure from bedding can be challenging.

Challenges of Using Manure in the Garden

Excess phosphorus: One challenge with using manure and manure-based fertilizers year after year is that manure has a higher phosphorus-to-nitrogen (P:N) ratio than plants require. Also, phosphorus (P) is less mobile in the soil than nitrogen (N), so you may see a soil buildup of phosphorus over time. Excess phosphorus can inhibit plant growth, so regular soil testing is the best way to keep track of this (we do a soil test every three to five years).

A good way to prevent a buildup of phosphorus in the first place is to alternate between manures and plant-based nitrogen fertilizers, such as alfalfa meal and legume cover crops, nonmanure animal sources like urine (yes, human urine), feather meal and blood meal, or fish emulsion. This diversity tips the scales in the direction of balance, along with providing a broader spectrum of nutrients. Here’s an example of how this might look in practice: You apply animal manure for three consecutive years, skip a year or two, and use one of the other nitrogen sources just mentioned, then go back to using manure again after the break.

Pathogens: All manure is rich in microorganisms, some beneficial and others harmful. The harmful organisms, called pathogens, can make you sick. Most pathogens break down during the composting process and with exposure to ultraviolet light (sunlight). Methods for aging or composting manure can help destroy them.

Weed seeds: Some manures contain viable weed seeds. The most likely culprit for these unwelcome hitchhikers is horse manure, since these animals have a single-chambered stomach and eat lots of plants and their seeds. Even ruminants (cows, goats, sheep, llamas), which have multichambered stomachs, can sometimes pass weed seeds unscathed in their manure.

If you’re getting manure from a new source, we suggest spreading some in a pot or tray and watering it to see what sprouts over a couple of weeks. It can be a major bummer to bring in nutrient-rich manure full of weed seeds, especially thorny or otherwise noxious weeds, such as Chloe’s nemesis, spiny amaranth.

If the inventory shows you a lot of nasty weeds, better to pass on that particular manure. If it’s weedy but the weeds are more benign (like clover and grasses), you can apply the manure and wait long enough before planting to make one or two passes over the area with a stirrup hoe to kill most of those baby weed plants.

Be sure to irrigate enough to sprout the seeds unless it rains sufficiently.

Persistent herbicides: If you can locate manure from organically raised animals, that’s ideal. If not, it’s worth inquiring which herbicides were used on anything the animals have eaten (pasture, hay, other feeds).

One class of herbicides in particular can persist even through the composting process: pyridine carboxylic acids. These include all herbicide products containing active ingredients in the pyridine family, especially aminocyclopyrachlor, aminopyralid, clopyralid, and picloram.

If these come into your garden with manure, your vegetable growth can become extremely stunted, or you may even have a barren garden, and this problem can persist for years. At this writing, the following products contain these toxic compounds:

Urine

Human urine is a fantastic free fertilizer for the garden. If you’re already responding to the ick factor, we encourage you to keep an open mind and read on.

Urine is rich in nitrogen and phosphorus, as well as lots of secondary nutrients and micronutrients that plants need for growth. It’s basically a well-balanced plant food that comes right out of your body every day, at no cost.

Currently, wastewater treatment systems and infrastructure around the world are under increased stress due to unpredictable weather and aging components, and human waste can end up polluting rivers, lakes, and groundwater when these systems fail. So when we use pee in our gardens, we’re not only giving our plants what they need for free, we’re also diverting from a waste stream and helping to protect wild water.

Field tests on hay crops conducted over several years at the Rich Earth Institute have shown equivalent yields between test plots fertilized with urine and those fertilized with chemical fertilizer. Both test plots had significantly higher yields than unfertilized plots. Forage quality remained high, and one farmer has been able to achieve a solid second cutting of hay where previous yields were not sufficient to warrant a second cutting.

Human urine is actually a much higher-quality fertilizer than human feces. This might seem surprising, since we’re so used to using manures of various kinds in the garden. In fact, human urine contains over eighty percent of the nitrogen and over sixty-five percent of the phosphorus that we flush away each day; pee has more of the good stuff plants need than poop does. Plus, urine doesn’t easily harbor pathogens and bacteria as feces do, and it’s relatively easy to sanitize, if need be.

Urine can carry some viruses and bacteria, so if you’re using it on vegetables you’ll be selling or sharing with folks outside your household, the World Health Organization recommends sanitizing it.

This just means either leaving it in a closed container for six months or more before using it, or pasteurizing by heating it to between 160 and 180°F (71 to 82°C) for thirty minutes. If you’re using urine from your own household for vegetables that will be eaten only by members of that household, sanitization isn’t necessary.

Both Natalie and Chloe have been using un-sanitized pee on their gardens for years and have never run into any issues. The Rich Earth Institute has found in their research that you’re more likely to catch a sickness from a roommate by sharing a kitchen or bathroom with them than by eating vegetables that were fertilized with their pee.

Challenges of Using Urine as a Fertilizer

It stinks: We’re not going to lie, a jug of pee is going to be a bit stinky. Adding white vinegar to your collection vessel can help dramatically. Rich Earth recommends four cups of vinegar for a 5-gallon jug of pee; you can make adjustments to this ratio based on your collection vessel.

Natalie has also used wood ashes to neutralize the smell. It can be handy to keep a small chamber pot or “pee jar” in your house that you pee in and rinse out regularly, then keep a bucket or larger container outside, where a little stink is not as offensive; be sure to cover this vessel with a snug lid to minimize odor and prevent bugs from flying in.

Salt accumulates: A lot of folks worry about salts accumulating in areas fertilized with urine.

In trials at the Rich Earth Institute, they haven’t found this to be an issue, but they do suggest extra caution and monitoring in greenhouses, container gardens, and very dry places. If salts do build up (as evidenced by a soil test), you can flush them out with fresh water.

Similarly, the Rich Earth Institute hasn’t recorded significant pH changes in their soil, but they suggest soil testing every few years (which is a good idea anyway) for monitoring levels in your particular conditions. Most urine is relatively neutral, with a pH of 6.0–7.5, but it can get fairly acidic or alkaline, depending on the person’s diet and health status, and can range from 4.5–8. A pH of 7 is neutral.

Pharmaceuticals leave residues: The most common “drug” that the Rich Earth Institute has found in urine they’ve studied is caffeine. This and all other drug residues, including pharmaceuticals, show up in such tiny amounts that they don’t think they’re worth worrying about. In contrast to the aquatic ecosystems where municipal wastewater ends up, soil ecosystems (especially biologically active garden soil) are equipped with microorganisms that can break down pharmaceutical residues, rendering them less harmful.

Then there’s the ick factor: This gets in the way for many gardeners who otherwise would love a free and effective fertilizer source. If you’re grossed out by using pee as a fertilizer, think about where your other fertilizers come from. Chemical fertilizers are mostly made from fossil fuels, and their manufacture produces climate-warming gases; manure is poop; fish emulsion is basically a dead fish smoothie; alfalfa meal and other vegan fertilizers require lots of energy and machinery to produce.

The bottom line: Death and decay and metabolic waste products are what fuel life on this planet.

Embracing the beauty of these cycles can turn the “ick factor” into an “awe factor.”

How to Use Urine in the Garden

Adults produce between 100 and 150 gallons of urine per year, containing about 9 pounds of nitrogen and 0.8 pounds of phosphorus.

As a reference, this amount of fertilizer can grow enough wheat for a loaf of bread every day of the year. The urine our households produce and use in our gardens creates more than enough nitrogen to satisfy the needs of our vegetables.

Depending on the size of your garden, you may not need to import any other nitrogen and phosphorus sources. Urine, however, does not replace the important roles of organic matter and mineral-rich amendments, such as kelp or borax, when they’re needed.

Pee carefully and don’t go overboard!

As with any nitrogen-containing fertilizer, you don’t want to overdo it with urine and end up polluting groundwater. Any amount of water-soluble nitrogen that isn’t taken up by green growing plants will wash away. Only use pee on plants that are already green and growing (not on germinating seeds, tiny seedlings, or plants that have moved into their fruiting stages).

Pour directly on the soil: The easiest way to apply urine is as a soil drench (meaning something poured, or peed, directly onto moist soil). If your soil is dry, dilute the urine with water. Chloe generally favors a 1:1 ratio, while Natalie tends to dilute more, with a 1:3 or 1:5 ratio. Alternatively, you can irrigate immediately after application. If you want to foliar feed with urine, which Natalie likes to do, dilute it to about 10 parts water per 1 part urine.

Note: Never spray undiluted urine directly on the leaves or stems of plants, but rather pour it into the soil about 4 inches from the base of the plant’s stem. An appropriate application rate is about 5 gallons per 100 square feet over the course of the growing season. We have never measured this out, because our gardens are fairly large and it’s harder to overdo it.

When we start to see manure and even urine not as garbage but as gifts, the whole story of our gardens begins to change.

Instead of importing fertility in bags and bottles, we can grow food in a way that honors the lives and cycles that make that food possible in the first place. It doesn’t require perfection or a complete overhaul of your system—just a willingness to pay attention, to experiment, and to return what you can. Over time, that simple practice turns a garden into an ongoing conversation with the land, one where the soil feeds you because, day by day, you’ve chosen to feed it back.

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Natalie Bogwalker and Chloe Lieberman are cofounders and codirectors of the Growing Wise gardening school, and Natalie is the founder of Wild Abundance, a school for permaculture, carpentry, and rewilding. Together, they’ve taught gardening to thousands of students around the United States.

Well Being Journal adapted the above excerpt from The New Natural Food Garden by Natalie Bogwalker and Chloe Lieberman. Copyright © 2026 by Chloe Lieberman and Natalie Bogwalker. Printed with permission from Storey Publishing, an imprint of Workman Publishing, a division of Hachette Book Group, LLC.