The Craigslist ad was pretty straightforward: free horse manure without shavings, you load and haul. Something for free for a little effort; that’s a good deal!
Or is it?
Fall is the time of year to add organic material to a garden bed and manure is black gold when it comes to a soil amendment. As the Craigslist ad shows, finding a source of manure is little more than a mouse click away. All the easier if you have a truck or trailer to haul it home with.
Because manures can carry bacteria, weed seed and bugs, all manures need to be composted or aged before they are put into a vegetable garden. Ask how long the pile has been sitting: the answer should be about six months. This gives the pile enough time to heat up to above 130 degrees for a period of time which kills most of the bad stuff.
Not all manures are created equal. Manure from herbivores (horses, cows, chickens, goats, llama and other grass eating animals is OK to use. Manure from pigs, dogs and cats is not because they can carry parasites and diseases humans can pick up. Horse manure will have more weed seed in it than other types because of the way the horse digests its hay. Chicken manure can be a bit smelly.
Manure is a great source of organic material and helps build up the soil’s ability to hold water, support soil life and provide aeration. Manures are also a source of nitrogen and other nutrients with rabbit having the highest level of nitrogen at about 2 percent while chicken is usually about 1 percent. Beef, sheep and horse are just under a percent while dairy cow manure is the lowest. These ranges are not exact and can vary widely depending on how much bedding and wood shavings are mixed into the manure and how it was handled at the farm. The nitrogen is in a slow release form that is available to the plants over a longer period.
Now back to the practical side of the great Craigslist offer. First and foremost is how close to town is the farm. If you have to drive a distance, it might be cheaper to buy it. Manure, especially wet manure, is heavy and if you have to load it yourself with a shovel, you better find some hungry kids who will work for a pizza to go with you. If the farmer will load with a tractor for a fee, take him up on it.
Lastly, how are you going to get the manure from your truck to the garden spot? Free isn’t going to sound very good if you have to haul it up a flight of steps and through a narrow gate a bucket at a time. Maybe those kids need another pizza.
Pat Munts is a Master Gardener who has gardened the same acre in Spokane Valley for 30 years. She can be reached by email at [email protected] inlandnwgardening.com
The all-natural organic way to improve native soils is to start by using Black Kow® composted cow manure, “The Mature Manure.” By mixing Black Kow® cow manure before planting, you do 3 important things:
- Provide moisture holding capacity to sandy soils. Black Kow® manure holds water and nutrients in the soil around the roots. The roots can use the water and nutrients when needed instead of letting the nutrients leach through the soil.
- Provide aeration and moisture holding capacity to hard, clay-type soils. Black Kow® cow manure helps break up those soils so that water and nutrients are available to the plant when needed.
- Give your plant’s roots the optimum environment in which to get started. Black Kow® cow manure contains millions of beneficial microbes. These microbes convert nitrogen and other nutrients into an easily available form for the plant. It is organic and contains nutrients that are released slowly without burning tender roots. These nutrients and moisture are held in the soil around the roots until the plant needs them.
Manure is a valuable soil amendment for home gardens.
Animal manure is a valuable soil amendment for home gardens. It not only supplies primary nutrients (nitrogen, phosphorus and potassium) and micronutrients for plant growth, but also is a source of organic matter. Increasing soil organic matter improves soil structure, increases the water holding capacity of sandy soils, improves drainage in clay soils, provides a source of slow release nutrients, and promotes growth of beneficial soil organisms. These manures used as fertilizers are typically from herbivores (i.e. plant-eating animals), such as cows, sheep, chickens, etc. (Never use cat, dog or pig manure in vegetable gardens or compost piles.)
The amount of nitrogen in and manure depends on many factors, including the type of animal it came from.
The nitrogen in manure is not available all at once to growing plants as much of it may be tied up in organic forms. Organic nitrogen becomes available to plants only after soil microorganisms decompose the organic compounds, converting the released N to NH4, which occurs over a period of years. The actual amount of this conversion varies considerably depending on the animal it came from, any bedding materials with it, temperature, moisture content, and handling. In general, about 30% to 50% of the organic nitrogen becomes available the first year, and the amount gradually decreases thereafter.
Fresh poultry manure is is particularly high in ammonia.
Fresh manure typically has high amounts of ammonium or soluble nitrogen. This results in a higher available nitrogen content compared to composted manure. Poultry manure is particularly high in ammonia and readily burns if over-applied. Because of the high amounts of ammonia-nitrogen in fresh manure, it should be incorporated 6 to 8 inches within 12 hours after application. Without incorporation much of the soluble nitrogen will be lost to the atmosphere as ammonia. If the manure is mixed in with bedding or litter this will dilute the nutrient content. If there are large amounts of straw or sawdust, nitrogen availability to plants may be lowered by increasing the C/N ratio. High carbon relative to nitrogen (greater than 25 /1) will tie up nitrogen.
Fresh horse manure often contains lots of weed seeds.
Salts in fresh manure also tend to be high — especially in chicken, turkey, or other poultry manure. To avoid salt damage, wait 3 to 4 weeks after application before planting anything in the area.
Fresh manure may contain high amounts of viable weed seeds, which can lead to a weed problem. Horse manure is notorious for this, since those animals don’t digest what they eat as well as many other animals do, and seeds pass intact through a horse’s digestive system.
Do NOT use fresh manure on vegetables, particularly root crops.
Because of the potential of transmitting human pathogens, such as E. coli, fresh manure should never be used on fruits and vegetables. If you are growing crops where the edible portion is in contact with the soil (such as carrots, beets, or potatoes) fresh manure applications should be made at least four months prior to harvest. On other edible crops, fresh manure applications should be made at least three months prior to harvest. With just a four month or so growing season, this means you should only apply fresh manure in the fall; not in the spring or during the growing season to any area that is or will be planted with food crops.
Composting manure eliminates some of the problems of fresh manure — including the odor. It is lighter and easier to haul since it has less moisture, and the composting process may kill weed seeds and pathogens if the pile heats above 145°F. But salts may be more concentrated and some of the nitrogen is lost, leaving the more stable organic forms. Composted manure has lower availability of nitrogen and will contribute more to the organic matter content of the soil compared to fresh manure.
Many brands of composed cow manure are available commercially.
However, unless applied at high rates, composted manure alone may not be able to supply all the nutrients for fast growing plants. It’s not as important to immediately incorporate composted manure into the soil as for fresh manure, but incorporating it in to a depth of 6 to 8 inches is recommended whenever possible to obtain the full benefit from the compost. If spread in the spring, it is best to wait a least one month before planting crops so the microbial activity it stimulates won’t interfere with seed germination.
If you have convenient access to a supply of fresh manure you can try composting it yourself, but most people just purchase bagged composted manure that is readily available in garden stores and nurseries.
Many animal manures are mixed with bedding such as wood shavings in this chicken coop.
So how much manure should you use? If you purchased bagged composted manure, the label on the package will tell you the nutrient content and application rates. If you’re dealing with buckets of fresh or aged manure from a friend’s farm, the contents of your backyard chicken coop, or a donation from a neighbor’s horse barn it may be much harder to estimate whether what you’re spreading in the garden is too much or too little or just right.
Farm animal manure varies in its nutrient content.
The nutrient content of farm manure varies considerably depending on many factors. The availability of the nutrients from the manure for plant growth will depend on the breakdown and release from of the organic components. Generally, 70 to 80% of the phosphorus and 80 to 90% of the potassium will be available from manure the first year after application. Calculating nitrogen availability is more complex as it is dependent on microbial activity to make it available for uptake.
Suggested rates of fresh manure or compost to apply to supply about 0.2 lb of available nitrogen per 100 square feet:
|Manure type||pounds to apply
per 100 square feet
|Dairy cow||no bedding||75|
A 5 gallon bucket holds about 25 lbs of fresh manure or compost, so you can estimate how much to use without actually weighing the materials. For example, use three buckets full of dairy manure without bedding spread over a 10 by 10 foot garden to add 0.2 pounds of available nitrogen. You’d need to add 8 buckets of composted cow manure over the same size area to apply the same amount of nitrogen.
A pot of black gold at the end of the rainbow.
In most cases, manure application is based on its nitrogen content and estimated availability for the first growing season. But remember that some manure contains high levels of phosphorus, so you may end up adding way too much phosphorus as you are incorporating enough manure to meet the plant’s nitrogen demands. It is important to have your soil tested to help determine if the level of phosphorus in the soil is building up too much (in which case you probably should use a different type of fertilizer that has low or no phosphorus for a while), as well as to know if other plant nutrient needs are being met with manure alone.
Proper use of manure in the garden can supply your plants with nutrients and help improve soil structure. Adding too much manure can lead to nitrate leaching, nutrient runoff, excessive vegetative growth and, for some manures, salt damage. And using fresh manure where food crops are grown poses risks for contamination with disease-causing pathogens. In general, when using manure (other than commercially processed products) in the home garden it is best to allow it to age first for 6 months to avoid any potential problems. An ideal way to do this is to spread the manure in the fall or winter and incorporate it into the garden in the spring before planting.
– Susan Mahr, University of Wisconsin – Madison
- Fertilize with Manure without Damaging Plants
- This Manure Will Destroy Your Garden!
- A Load of Manure is a Gardener’s Paradise…Naturally
- That Herbicide is Poison
- Toxic Manure in the Garden is No Joke
- This situation is bad manure, and gardeners everywhere need to be warned!
- Here’s how to keep your gardens safe.
- About the Author
Fertilize with Manure without Damaging Plants
Manure is one of the best additions for your garden. It improves soil and fertilizes your plants by helping them to absorb water, oxygen and other nutrients, which are essential for their health. Other benefits of manure are that it’s inexpensive, readily available and easy to mix into your garden soil.
Fertilizer and Amendment
Manure is both a fertilizer and a soil amendment (material added to improve soil). Manure slowly releases nutrients into the soil that plants can easily absorb. Manure contains nitrogen, phosphorus, potassium and micronutrients, which are important for plant health. Nitrogen is the most important nutrient that plants need and is responsible for rapid plant growth and the green color of plants.
Fresh manure has a very strong odor and is harmful to plants because it contains high levels of nitrogen and ammonia that can “burn” plants. Plants in contact with fresh manure will rapidly dehydrate, causing the leaves to turn brown and wither. This process is called burning.
Before manure can be used to fertilize plants, it must go through an aging process called composting. In this process, fresh manure sits for 3 to 12 months. As the manure ages, nitrogen changes into a form that won’t burn plants, and any pathogens present in the manure are also killed. Another benefit from composting manure is that it loses its odor. (That’s a big benefit!)
Cow manure is the most popular source of manure for plants because it doesn’t contain high amounts of nitrogen and is less likely to burn plants. Other sources of manure for the garden are horses, chickens and rabbits. Based on the type of animal, manure has different levels of nitrogen. Rabbit manure has the highest level of nitrogen, followed by chicken, horse and cow manure, which has the lowest amount.
How to Apply Manure
To apply manure, add a 2 to 3 in. layer of manure on top of existing soil and mix in well. Like cow manure, horse, chicken and rabbit manure are great for your garden, but because they have higher levels of nitrogen, make sure that they are not fresh and that they have been composted. Do not use manure from cats, dogs or pigs, which contains dangerous pathogens.
Fresh manure can be added directly to soil as long as there aren’t any growing plants. Mix the fresh manure with the existing soil in fall and don’t add plants until spring arrives. By then, the manure will have aged long enough so it won’t burn plants. It is especially important not to apply fresh manure during the growing season to vegetable gardens, because the pathogens found in fresh manure can contaminate vegetables.
Adding manure to your garden is a great way to fertilize your plants and improve the soil. Just be sure that the manure has been composted—keep in mind that “older is better” when adding manure to your garden.
Manure is generally considered one of the best amendments you can add to your garden. At least it used to be. Here’s how manure in the garden may actually destroy your soil and plants for a long time.
This article may contain affiliate links. Please read my disclosure for more info.
The following article was written by David the Good of The Survival Gardener.
David and I first connected after he wrote an honest and thorough review of my book, ‘The Suburban Micro-Farm’, for Mother Earth News. David is an expert at home-scale food production and I was thrilled that he enjoyed it.
The truth is, herbicide-laced manure is a widespread problem that can completely destroy a garden. David has been on the front lines of this problem and was one of the first to sound the alarm.
I’m grateful he’s sharing this information with us so that we may prevent this devastating and costly misfortune from occurring in our own gardens. — Amy
This Manure Will Destroy Your Garden!
Manure is rich in nitrogen, organic matter and a variety of minerals, adding nutrition and tilth to the soil and ensuring rich harvests of green and happy vegetables. It’s generally considered to be one of the best amendments you can add to your garden.
At least it used to be.
Now adding manure to your garden is playing Russian roulette with your plants. There’s a very good chance that it will completely destroy your beds and cause your plants to grow into twisted parodies of their proper growth pattern before dying ugly and unproductive deaths.
A Load of Manure is a Gardener’s Paradise…Naturally
Some time back I did a very normal thing for an organic gardener: I bought a trailer of manure from a local dairy farm and had it dropped in my front yard.
I then proceeded to spread it across multiple beds, add it around the trees in my front yard food forest, and turn it into the ground along the front fence line where I was planting dozens of newly purchased thornless blackberries.
>>>Read more about creating food forests.
A few weeks later, I planted my gardens – and everything started going very, very wrong. My transplanted tomatoes and eggplants started to twist up. They were still green, but their leaves were thick and curled and the amount of new growth was much smaller than it should have been.
Something was very wrong.
My thought upon seeing the weird growth in my tomatoes and eggplants was that I was dealing with a virus. They were both Solanaceae family – maybe it was some weird and horrible disease I’d never seen before?
Then some of the edges of the blackberry leaves started twisting and turning brown.
A virus wouldn’t jump families – blackberries are Rosaceae! I had to look elsewhere.
I noticed the blackberry leaves were deep green, despite their strange growth. Perhaps there was too much nitrogen in the manure? The manure had been composted for over six months, according to the farmer. And it certainly didn’t look or smell fresh. It was earthy and crumbly, well-aged stuff. It looked just like something you’d want to add to your garden.
Then the mulberry tree started looking weird. And the pecan trees and the olive exhibited the same symptoms.
Would you like to learn more about using soil amendments safely in the garden?
You’ll find more information like this in my award-winning book, The Suburban Micro-Farm.
That Herbicide is Poison
From my reading, it wasn’t too much nitrogen. The symptoms were too strange. And it wasn’t a virus.
The only thing in common between all these sick plants was one big load of manure.
I called the local master gardeners and shared the symptoms and they had nothing helpful to suggest, so I started searching on my own, looking up phrases like “twisting leaves manure,” until I came across an article about a community garden disaster on the left coast.
They had purchased a load of manure compost, then lost many of their plants because of a recently released herbicide designed for hay growers and cattle farmers.
I had met my nemesis.
I called the farmer who had sold me the manure and asked him if he’d sprayed anything on his hay fields. He told me he had tried a new product recommended by the University of Florida for the elimination of spiny pigweed, an obnoxious recurring weed in his pastures. “It worked really well,” he told me.
I shared that all my plants were dying and asked if he could find out what he’d sprayed. I was pretty sure I knew already, but when he sent me a picture of the label, I knew for sure.
It was Grazon, an aminopyralid-based toxin from Dow AgroSciences.
Herbicide Damage -Eggplant. Image by David The Good.
Contaminated compost: aminopyralid effect on tomatoes. Photo by Karen Land.
Grazon Damage. Image by Luzette of Buffalo Girl Soaps.
Toxic Manure in the Garden is No Joke
The farmer was quite upset by my report. He had sprayed his pasture the previous summer. That was about nine months before I called him, and he was told Grazon was safe for animals to consume.
Armed with my new research, I shared that the toxin could continue killing plants for years, even after being eaten by animals, then excreted, then composted for months.
He refunded the $60 I’d spent for the manure and apologized, telling me he wouldn’t spray again and that he had a lot of people that bought his manure.
I didn’t blame him for the mistake and I didn’t ask for his help replacing the thousand dollars or so of destroyed produce and perennials. We all make mistakes and he seemed like a decent guy.
I reserved my blame instead for the University of Florida, Dow AgroSciences and the government that lets these poisons into our gardens.
By the time I knew what was going on, I had lost the first half of the growing season. Most of my garden beds were loaded with this manure – and my poor blackberries were twisted and dying, along with multiple fruit trees.
This situation is bad manure, and gardeners everywhere need to be warned!
I was angry and feeling sick over the whole thing, so I called my friend Carolyn who owned the local Natural Awakenings magazine and asked if I could write an article warning other gardeners about the new danger of using manure in the garden.
She agreed, and that led to me being contacted by Mother Earth News and becoming a blogger with them. Eventually, the manure fiasco led to me dedicating myself to making all my own compost – and that led to my book Compost Everything: The Good Guide to Extreme Composting.
My manure-in-the-garden fiasco ended up launching my writing career. God works in mysterious ways. My terrible year of poisoned gardens ended up saving a lot of other people’s gardens – or helping them figure out what happened after a poisoning event.
Person after person has written me to share tales of wrecked gardens. Some people lost beds because of contaminated hay they used in their compost. Others lost beds due to manure. Still others purchased compost or garden soil and had it kill their plants.
Aminopyralids are all over the place now and it’s a minefield for gardeners.
New gardeners are really in a bad place now, as they often don’t know what to expect from their plants. When Aminopyralid symptoms strike, they just assume they made a mistake, not that their beds were poisoned.
Here’s how to keep your gardens safe.
1. Don’t purchase compost.
Many facilities still don’t have proper safeguards in place to keep their product uncontaminated.
2. Don’t use manure from grazing animals.
That neighbor offering you well-rotted horse manure? A decade ago I would have said “great!” Now I would say “absolutely not!”.
Though your neighbor might not spray his fields, he likely buys hay – and a lot of hayfields are now sprayed. It happens again and again and again. I have heard reports that even store-bought bagged manure is killing gardens.
Just say no to manure in the garden from grazing animals.
Remember, though, that Grazon is used to kill broadleaf weeds in hay. If you can get manure from non-grazing animals, it should be fine. Chickens and rabbits should be okay, unless you use straw or hay as bedding. Rabbits may eat a little grass but they are usually fed with alfalfa pellets and alfalfa is not sprayed with Aminopyralids.
3. Avoid hay and straw in your compost or as mulch.
A friend lost a chunk of her food forest plants after picking up a load of well-rotted hay and spreading it around. Members of the grass family may be sprayed with Aminopyralid-containing pesticides. Avoid.
4. Make your own compost.
Learn to compost everything. Fall leaves, shredded paper, fish guts, eggshells, lasagna – whatever. The more organic material you can add to your compost pile and eventually to your gardens, the less you need to buy to amend your gardens.
I compost all kitchen scraps, including meat. Gather lots of leaves or grass clippings from your (unsprayed!) yard and throw them over stuff that might stink. You can also cover your bin to keep out vermin. Nature will do the rest. It’s just a matter of time, not perfection.
This isn’t an easy time to be a gardener. The world is toxic and there are plenty of pitfalls, including the use of manure as an amendment.
I’m not exaggerating when I say this is a widespread problem. It’s no longer a good idea to add manure to your garden. If you do, you’re running a big risk and can destroy your plants because someone sprayed toxins on a field somewhere far from your garden.
It’s not easy to find good alternatives, but it needs to be done. Watch your back and start making your own compost. It may save you some serious heartache.
Get David’s tips for fixing Grazon contamination.
A Note from Amy
It’s important to support your local farmers who commit to doing honest and good work. If you have a farmer who has been supplying you with material such as manure, hay, straw, or compost, then I encourage you to start a conversation about herbicide contamination.
Ask questions. Learn about their process. If they have control over all of the materials in the supply chain and emphatically say they do not spray, then they deserve to have your business.
If the farmer outsources any of those materials (hay or straw?), it’s more difficult to know for sure. Ask for the contact info of their supplier. Ask more hard questions. Go with your gut. Don’t assume that all farmers are dishonest, because that is certainly not the case, but obviously you want to be cautious.
Farmers are busy. When their extension office tells them a widely used (herbicide) product is safe, they may go with it, having no idea of its wrath.
Have you suffered problems due to herbicide-laced manure in the garden? What changes will you make to your gardening routine to avoid it?
About the Author
David The Good is the author of multiple gardening books including Compost Everything: The Good Guide to Extreme Composting, Totally Crazy Easy Florida Gardening, Grow or Die: The Good Guide to Survival Gardening and his latest release Turned Earth: A Jack Broccoli Novel, the world’s first gardening thriller.
David has been featured in Mother Earth News, Backwoods Home, Heirloom Gardener Magazine, The Grow Network and other outlets. He is also the creator of TheSurvivalGardener.com. David currently lives with his wife Rachel and their children somewhere in Central America where they collect rare edible plants and enjoy growing everything from ackee to yams.
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>>> Get my free 19-page Guide to Organic Soil Amendments for more ideas: