Composting manure for spring

Q. How do you know how much and what kind of animal manure to use on the garden this spring?

Richard from Canfield

A. Ahh … organic matter. Manure is just one of the great options to add to your vegetable garden — or even the flower garden — to improve the soil.

Most of us need to add organic matter due to the heavy, clay soils found here in the Mahoning Valley.

Manure also adds nutrients.

Organic matter holds on to water and nutrients and will improve drainage and aeration in our clay soils. An organic matter level of 4 percent to 5 percent would be optimal for growing vegetables.

To determine the organic matter level in your soil, you should complete a soil test every two to three years.

You can learn more about soil testing at

Fresh or aged cow and horse manure are generally the easiest to obtain locally. You can use other manures.

You can also find bagged manures at your local garden centers.

Incorporating fresh manure in the garden is a generally accepted practice, but should be done in fall. The national organic standards require manure to be incorporated 120 days before the edible portion of the crop touching the soil. Based on this, fall is the best time to use fresh manure if you do not plan to compost.

Composting manure is the best option if you want to apply in spring. Using a compost thermometer, allow the pile to get to 131‚ó¶degrees and stay at this temperature for at least three days. This will allow the temperature to get well above this level to kill weed seeds and harmful pathogens. Maintain the pile for at least 15 days and turn it at least five times.

Horse manure is probably the easiest to obtain, but can be challenging. Due to the sawdust and wood shavings used in the bedding of horses, fresh horse manure can rob your plants of nitrogen. Thus, composting is a must if you intend to use it in spring.

Aged manure is not always what you think it is. While part of the aged manure that was at the center of a pile was composting, the outer portion did not get hot enough to kill the weed seeds and pathogens.

Generally, an inch of compost or manure is what you need. For a 10x10 garden (100 square feet), that’s about 1/3 of a cubic yard (4.3 square feet).

To read details about manure and other organic matter to add to your garden this spring or next fall, go to:

To gain a better understanding of using horse manure, goto:

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hot line at 330-533-5538 to submit your questions. Clinic hours vary this time of year due to the winter season.