Adding Manure as Organic Matter, to Improve Garden Soil

Highland Cow
Photo: scotsann

Why Use Manure in the Garden?

Manure refers to solid and liquid animal waste and often comes with some of the bedding material (straw, hay, saw dust...) mixed in. Odd as it seems, animal manure is an organic material that is often used to improve garden soil. Alone or added to compost, it improves soil texture, with an added bonus of some soil nutrients. You can use manure from just about any farm animal and even some exotic wild animals.

Cow, sheep and chicken manure are the most popular varieties, but there are several more. The manures to avoid because of their disease potential for humans are: cat, dog, pig, and human manures.

Why You Shouldn't Use Fresh Manure Around Plants

This wonderful, free resource does require some patience, though. Fresh manure is too high in nitrogen and ammonia and can easily burn plants, if it comes in contact with them. It can also contain bacteria that would contaminate any edible plants growing near it. You need to compost manure, or let it rot, for at least 6 months to a year, before it is ready to e used in the garden. You can throw it in a compost pile or let it rot on its own, although it will have a strong odor if your do.

Some farmers will top their fields with fresh manure in the fall and let it age through the winter. This works, but it's not the most efficient use of manure. If you choose to try this method, the USDA National Organic Program (NOP) recommends you apply fresh manure at least 120 days before harvest of vegetables that come in contact with the soil (root  crops, low growing leafy crops) and at least 90 days for vegetables that don't come in contact with soil.

Where to Find Sources of Manure

Farms and zoos are your best bets for finding free manure, however as gardening becomes more and more popular, farmers and zookeepers are wising up and selling their manures as an additional source of income. Even if they aren't giving it away, it is still quite inexpensive, if you have a truck to go and pick it up yourself.

Plan on a quick trip to the car wash, if you do.

Some Other Considerations, when Using Manure in the Garden

  • When you go to pick up manure, head for the oldest pile they have. It may have already gone through a few months of rotting. That means you can use it sooner and it shouldn't smell as foul as the freshest manure.
  • Don't be afraid of manure piles with lots of bedding in them. The more bedding there is in fresh compost, the faster it rots.
  • Ask if the manure has been sprayed with anything. Some farmers will use pesticides on manure piles to keep the flies in check.
  • Bagged manure costs considerably more, but it is already composted for you and ready to use.
  • Use rotted manure as you would compost. Plan on amending your beds with it annually.
  • Strongest Smelling Manures: Chicken and Rabbit
  • Mildest Smelling Manure: Sheep (It's also drier and easier to spread.)


Nutrient Content of Common Animal Manures

AnimalN-P-K Ratio