Turn manure into compost for your garden

CORVALLIS, Ore. – Don't get rid of the manure that chickens, horses or llamas leave behind.

Livestock manure is rich in nutrients that make it a great organic fertilizer for your garden, said Melissa Fery, Oregon State University Extension Service Small Farms faculty and associate professor of practice in the College of Agricultural Sciences.

"Manure is a low-cost fertilizer and a wonderful way to utilize nutrients instead of creating a large pile that is not getting used and could be harmful to water quality," she said.

If you add livestock manure to your soil, you'll not only improve the quality of the soil but you also won't need to water your garden as much. Over time, organic amendments like manure help soil store more water.

Livestock manures are good sources of nitrogen, phosphorous, potassium and other nutrients that plants need to thrive. But the amount of each nutrient varies depending on the animal's diet and digestive system, and the amount and type of bedding used, Fery said.

Fery recommended hot composting manure before applying it to your garden to kill parasites and reduce seeds from weeds. Composted manure is also easier to shovel and spread. Hot composting balances food, water and air in a compost pile to favor the growth of microorganisms that thrive in high temperatures. If you’re using uncomposted manure, dig it into the soil at least 90 days before harvest for food safety.

"It takes at least one-half cubic yard of fresh organic matter for a compost pile to heat up and reach the recommended temperatures for hot composting," said Nick Andrews, Organic Vegetable Extension specialist. “The pile should also have a balanced carbon-to-nitrogen ratio and good moisture and air.”

Make the bins big enough to hold a pile that could get 4-6 feet high and 3-5 feet wide.

Start by building two bins

A simple way to start is by building two bins out of pallets or boards. The first bin is for making the compost and the second is for the final stage of decomposition, also known as curing. Curing stabilizes the compost and can take several months. Make the bins big enough to hold a pile that could get 4-6 feet high and 3-5 feet wide.

Mix raw livestock manure with brown leaves, straw, spoiled hay or shredded paper in the first bin. If using manure mixed with bedding, it will probably have a good carbon-to-nitrogen ratio and you don't need to add anything else, Andrews said. Thick layers of one material might not decompose quickly if you don't have a balanced carbon-to-nitrogen ratio, he added.

It's important for the pile to have sufficient moisture, Andrews said. Wearing gloves, squeeze the organic matter firmly in your hand. You should be able to squeeze a few drops out of it or at least make your glove wet. If you can't, add water to the pile. If your pile is too wet, mix in some dry organic matter like leaves. Turn the pile in the first bin with a pitchfork a few times during the first month as it heats up. The pile should heat to 130-140 degrees. When conditions are ideal, compost can heat up within one day, Andrews said.

After the pile cools down to an ambient temperature, transfer it to the second bin or apply it to your garden. Like cheese, compost can improve with age and well-cured compost that’s been allowed to decompose for another two to six months can be used in your potting soil. Horse manure may take longer to break down if combined with sawdust or straw bedding used in the animal's stall. Wear gloves when touching raw compost and/or wash your hands afterward.

Spread composted manure in your garden in small amounts, about 1/2- to 1-inch deep. To prevent pollution, store compost away from water sources and cover the pile with a tarp when you expect heavy rain. Don't keep applying excessive amounts of compost year after year, Fery said.

Contact Master Gardeners at the Extension office in your county if you have composting questions. Find your local office.

The OSU Extension Service offers the following guides on composting in its online catalog:

Was this page helpful?

Related Content from OSU Extension

Have a question? Ask Extension!

Ask Extension is a way for you to get answers from the Oregon State University Extension Service. We have experts in family and health, community development, food and agriculture, coastal issues, forestry, programs for young people, and gardening.