A Guide to Fertilizing With Animal Manure

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The process of growing fruits, vegetables and flowers naturally depletes the nutrients in the soil. There are ways to add fertilizer that do not require chemicals. Instead, use the stuff nature provides by adding animal manure to your garden beds.

Not all poop is created equal! Some can actually be used fresh from the animal and used as a soil amendment or side dressing fertilizer with the plants. Others must be aged or composted before they are suitable. Use these guidelines as a beginning step and then research the specifics of each individual kind of manure. I’ve provided publication links for you at the end of this article.

The Composting Process

In all cases the process of composting manure is simple. You’ll first need to select a site for a compost heap. Mix the animal manure you’ve collected from your animals with other organic material such as hay, grass clippings or straw. If you regularly feed hay to your stock, you may already have plenty of hay intermixed with the manure. In this case, you might not need to add much in the way of additional organic matter.

Composting requires regular introduction of oxygen to the pile to stimulate aerobic microorganisms that feed on the organic components. This will convert the organic material to a nutrient-rich soil amendment. Remember to turn the pile every few weeks and after 6 months you will have a wonderful product ready to use in your yard.

Another option is to spread fresh manure directly on the soil in the fall. As long as there aren’t any growing plants you can mix the fresh manure with the existing soil in fall and then plant as usual when spring arrives. By then, the manure will have aged long enough so it won’t burn plants.

These manures can be used directly in the garden and do not require composting.

Rabbit–Fresh rabbit manure is approximately 2% nitrogen, 1% phosphorus and 1% potassium, which makes a nice general purpose fertilizer. It is easy to handle and not messy, or smelly. You can use it directly from under the hutch, it won’t burn plants. Rabbit manure also makes a great addition to your compost pile and will attract earthworms. A family of 3 to 4 rabbits will provide most of your regular fertilizer needs.

Worm Castings–A great source of macro- and micro-nutrients, it’s odorless, doesn’t burn plants, even if applied fresh, and is good at stimulating microbial growth in soil. You can buy worm castings or raise the worms yourself. However, you’ll need lots of worms to make enough castings to feed your garden. It’s best to stretch the castings by making a tea out of the castings to feed plants more readily or use it as a side dressing for plants needing a boost.

Composting is necessary before using these in your food garden.

These manures should be composted, or aged, for at least 6 months, but preferably a year before use. 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.

Chicken-This manure is highest in nitrogen and phosphorous and the nutrients are quickly available to plants. The urea nitrogen can easily burn plan roots, so this must be composted before it can be used around plants. The high nitrogen content makes it great for leafy greens. It has few weed seeds and diseases.

Horse-Probably one of the easiest manures to find locally, it’s a good all-purpose product, but like cow manure, not necessarily high in nutrients. Since a horse only digests one-quarter of the grass and seeds it eats, its poop is high in weed seeds. You must compost or you will introduce those weeds into your garden.

Cow-This is a good all-purpose manure. It has a balance of nutrients, but they are low in quantity. It’s more often used as a soil conditioner to improve soil structure by adding organic matter than as a way to deliver lots of nutrients to plants. Since cows have 4 stomachs and their food is well digested, the organic matter and weed seeds are well broken down.

Goat and Sheep-If your animals spend any part of the year in barns, stalls, pens, or feeding areas you will need to deal with manure from those areas. Manure is not just the urine and feces from livestock, but also the bedding, runoff, spilled feed, and anything else mixed with it.

These should never be used in food production or herb gardens.

Parasites that may be in these types of manure are more likely to survive and infect people than those in other types of manure. It is also important to keep your pets out of your vegetable garden

Cat, dog and pigs, being omnivores, produce waste that harbors harmful bacteria, things that would make us sick if our food were to come into close contact with it. If you are composting with the intention of using that compost anywhere near edible crops, do not compost dog, cat, and pig waste.

If you are going to give it a try for your flower garden or lawn, be aware that you will need to let this compost sit for as long as you can, even after it has broken down and looks like good, crumbly compost. At least two years is a good amount of time, enough time for the pathogens to all die off.

If I haven’t scared you off and you still want to give it a go, follow these guidelines from Organic Gardening.

General Guidelines for Raw Manure

If you do intend to use raw manure as a soil amendment or fertilizer source on your garden, follow these guidelines from the University of Maine:

Apply raw manure at least 120 days before harvesting a crop that has the potential for soil contact (leafy greens, root crops, etc). The USDA National Organic Program (NOP) standards allow a 90-day period between manure application and harvest for crops that don’t have direct contact potential with soil.
For some gardeners, the best time to apply raw manure to your garden may be in the fall after harvest; incorporate it into the soil and plant a cover crop to hold nutrients over the winter. This should be done before October 1 for good cover crop establishment.
Never use raw manure as a side dress to growing plants. Manure that is incorporated and distributed throughout the soil has a much lower risk of passing pathogens to the growing crop.

Consider the source if you still want to use raw animal manure in your garden. Are the animals in the herd or flock healthy? Is there a parasite problem that requires regular deworming? Does the farm use antibiotics as a regular component of their feeding program? See this University of Maine Bulletin for more information.

How much poop do you need?

According to Garden.org, “As a soil conditioner, generally you can use 40 pounds of composted manure per 100 square feet of garden. That’s about a bag or two of purchased composted manure. If applying composted manures to existing beds that are already very fertile, a 1- to 2-inch thick layer is probably sufficient. On poor soils, double that amount.”