Fresh vs. baked
Although some farmers regularly spread fresh manure in their fields, backyard gardeners should compost or cure plant-based manure before adding it to soil.
Composting manure at 131 degrees F (compost heats up naturally; check temps using a compost thermometer) for at least 15 days does the following:
- Kills harmful pathogens, such as E. coli.
- Kills weeds’ undigested seeds.
- Dilutes ammonia that burns plants.
- Stabilizes nitrogen into slow-release compounds.
- Reduces odors.
Turn your composting manure pile every few days to ensure that all bits of manure are composted. When composting, more time is better, but pathogens will be dead in 15 days at 131 degrees F.
If you don’t have a compost pile, you can spread fresh manure on your garden in the fall, let it dry and cure over winter for at least three months, then turn it into the soil in spring. Dried manure is lighter and flakier than composted manure, and will leaven your soil and increase drainage.
Which poo is best?
Before selecting fresh manure, test your soil to determine what nutrients it lacks; then select manure that supplies needed elements.
- Fresh turkey manure contains twice the amount of nitrogen as cow manure.
- Sheep manure contains more potash than horse poop.
- Rabbit manure breaks down quickly and doesn’t burn plants.
To see nutrients in various types of manure, check out this information from the USDA.
Alpaca manure, rich in nitrogen and potassium, currently is in fashion among garden enthusiasts. Alpacas take 50 hours to digest food (horses take 1 hour), and produce poop pellets, which are easy to collect and spread.
Here’s a look at the Double “O” Alpacas farm in Gainesville, Va.
Caution! Never use meat-based manure from dogs or cats, which contain pathogens that can sicken humans.
Where to get manure
- If you keep chickens, horses, rabbits, or cows, you know where to find free manure for your garden. Most neighbors who keep livestock will be happy to let you muck out a stall or cage and keep all the fresh manure you can carry.
- Many alpaca breeders age poop in fields, and then give the cured manure to gardeners for free. See if there’s an alpaca breeder in your area.
- Garden centers and big box hardware stores sell bags of composted manure ($8 for 40 pounds of composted cow manure).
- Some zoos compost manure from their resident leaf-eaters — elephants, hippos, zebras, giraffes, gazelles — and either give or sell it to the public. Manure from Seattle’s Woodland Park Zoo is so popular that it holds fall and spring lotteries for the right to purchase its composted “Zoo Doo” ($8-$10 for a garbage can full). Call your local zoo to determine its poo policy.
How to spread manure
What to wear: Wear gloves, long sleeves, pants, and shoes or boots you can leave by the door: You don’t want to track manure into the house. To prevent contamination, some gardeners don’t harvest vegetables in the same clothes they wear to spread manure.
After working in the garden, launder clothes in hot water.
How much: Generally spread about 40 lbs. of composted manure over 100 sq. ft.
How to apply: Use a shovel or spade to turn composed manure into the top 6-9 inches of soil; side-dress plants with aged manure; or treat plants to a manure tea made by soaking bags of manure in watering cans or tubs.