PHOTO: iStock/Thinkstock
January 18, 2016

During my Master Gardener days, I remember listening to a soil scientist from Utah State University give a presentation on poop. Not just any poop, of course; this presentation was about building quality soil for food production in the backyard garden, and the focus eventually turned to manure. Grant E. Cardon, USU extension soil specialist, bemusedly recounted to us the looks on his interns’ faces when he explained that for several weeks their lab would be receiving sample after sample of manure from across the great state of Utah in order to compile some general information on the samplings. They weren’t exactly thrilled.

I can’t really imagine why, as manure is one of my favorite things. If you’re lucky enough to be able to keep chickens or goats on your urban farm, I’m guessing you are likewise enamored of what comes out of the south end of those animals. We’re such garden nerds, we’d rather have composted manure than bricks of gold.

What makes people so thrilled with the manure of chickens, goats, cows and horses? As Cardon noted in the results of his manure sampling, “Increasingly, growers and homeowners alike are looking to local manure and compost products as a source of fertilizer and for soil conditioning.” You can purchase chemically prepared fertilizers for your garden beds, but why pay for something you can produce in your backyard or find for free in your community?

Must Have Manure

Before applying manure to your garden—or any other amendment, for that matter—the first thing you should do is test your soil. The results of a soil test will show you the nutritional makeup of your soil and in what areas you’ll need to improve deficiencies. Your local cooperative extension office can help you with this.

In general, gardeners are looking to increase the nitrogen, phosphorus and potassium (NPK) levels in their soil. There are other micronutrients required in healthy soils, but NPK are the big guns and they make up most fertilizers.

Manure has a lot to offer that commercial fertilizers don’t provide. For one, if you or a neighbor keeps the the animal, the manure is free or very cheap, which isn’t true of commercial organic fertilizers. Also, manure improves your soil’s structure and tilth, making it more permeable while holding moisture. Plus, it’s a simple, sustainable way to add nutrients back into your soil without having to rely on outside sources of fertilizer.

By properly composting manure, you eliminate the risk of contaminating your crops with pathogens, like salmonella. You can add a big batch of raw manure to any garden beds left fallow in the fall so that potential pathogens can dissipate and the manure can mellow over the winter. This is especially true of chicken manure, which contains high levels of nitrogen that can burn plants. You can also apply it in early spring so it can cool and begin to break down. Avoid applying fresh manure in any area where you’ll be harvesting in the next 120 days; however, I apply my composted manure as I need it during the height of plant production.

Be aware that manure contains salt in varying levels. If you live in a dry climate, you’re probably already used to watching salinity levels in your soil, so manure from a healthy, clean-fed animal is going to be the least of your saline problems. With a normal watering/rain pattern, salinity is controlled. Also, be judicious about application: When over-applied, the phosphorus can bind up other elements, making them unavailable.

Chicken Manure

Chicken manure is widely regarded as the best—read: most nutritive—manure. (Don’t tell that to the rabbit people, though.) It ranks as one of the highest in nitrogen levels and has ample phosphorus. Cardon (or rather, his manure-laden interns) recorded that chicken manure had the highest nitrogen level of the manure samples tested—6.62 percent. Comparatively, swine manure was the second-highest, coming in at 1.79 percent. Note that these percentages will vary by region, so check with your local extension agent to see what testing, if any, has been done in your area.

High nitrogen levels have a drawback: Nitrogen is hot. In order to avoid damage to plants, actively compost fresh chicken manure for at least four weeks before applying it. You can try side-dressing crops with raw chicken manure—nitrogen promotes leaf growth, so it’s particularly helpful for leafy greens—but note that you might have to experiment to find success.

Chicken manure also comes with high levels of phosphorus, which can interfere with the soil’s absorption of other nutrients, like iron and zinc. Once in the soil, those elevated levels of phosphorus can stick around for several years, as the plants can only filter out so much in a given season. If you’re applying a lot of chicken manure for the sole purpose of raising your nitrogen levels—even if you compost it well—apply it judiciously and use a nitrogen-fixing cover crop along with it, so you’re not depending on manure alone to bring up nitrogen content. Like sea salt on a meal, a little goes a long way.

Goat Manure

Goat manure may not be stuffed with nitrogen but it’s certainly there and if you’re using goat droppings that are mixed with urine, the nitrogen levels will be increased. The trade-off for less nitrogen overall is a mellower poop.

Goat manure is considered cool, and it has a more balanced pH and less salt. It’s also much drier than chicken manure, dropping to the ground in polite, little pellets, much like a rabbit’s poop only a bit larger. These pelletized droppings allow for more air in the composting manure pile, and the dry nature allows it to compost faster. Unlike its chicken counterpart, goat dung is practically odorless. Although goat manure can contain some weed seeds, overall it doesn’t seem to attract maggots and flies as readily as chicken manure.

It’s also light and easy to move, making working goat manure into garden beds a pretty easy job. I’ve put goat manure in the garden in the early spring and those beds are ready to plant in a matter of weeks. In short, a clean-fed and properly cared for goat will produce a mild but effective manure each year without too much work on your part. Again, a little goes a long way, even if you’re using a manure tea, which will work nicely for any manure, not just goat.

Make Your Choice

The decision to amend your with chicken manure or goat manure is for you to decide. As for me, I’ll take both. I usually pile up my chicken manure after the early coop cleaning in March and let it compost somewhere out of the way. I turn it a little and let the sprinklers water it, but I mostly ignore it until July when I want to give the garden a boost. My goat manure I directly apply early to the soil for the spring garden and at the end of summer for the fall garden. Personally, I prefer goat manure because it’s less work: Just sprinkle and wait a few weeks for it to break down.

The truth is, there’s a place for most livestock poop in our gardens. The key is to be aware of your dirt’s dynamics through soil testing and to keep your applications of natural mulches, composts and manures varied and balanced. Replacing your store-bought fertilizers with natural additives isn’t complicated if you remember to let manure mellow and apply it with care.



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