Composting Manure

The Livestock and Urban Waste Research (LUW) Team at the University of Illinois explains how composting works. From Swine Waste Economical and Environmental Treatment Alternatives (SWEETA).
calendar icon 1 January 2012
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Composting is an age old practice of waste management whereby the organic components of the waste streams are biologically decomposed under controlled conditions to a stabilized state that can be safely handled, stored or applied to land as a soil amendment.

Composting can occur in the presence of oxygen referred to as aerobic composting, or in the absence of oxygen referred to as anaerobic composting. Most modern compost systems are aerobic for important reasons.

Aerobic composting is:

  • Free from objectionable odor.
  • Makes pathogens and weed seeds inactive.
  • Relatively inexpensive.
  • Little technological input.

There are three methods of aerobic composting with the windrow method being the most cost effective.

Methods of Aerobic Composting

  • Vessel
  • Static Pile
  • Windrow

Raw Materials

The raw materials for composting can be split into two categories: Carbon sources and Nitrogen sources.

Characteristics of Nitrogen Sources: Examples of Nitrogen Sources:
Wet Livestock manure
Decompose quickly Food waste
High in nitrogen Grass
High bulk density
Not very rigid

Characteristics of Carbon Sources: Examples of Carbon Sources:
Dryer Corn Stalks
Decompose slowly Leaves
Low in nitrogen Sawdust
Low bulk density Wood chips
Somewhat rigid

Fresh Compost: Has undergone partial decomposition, but it is not stabilized and continues to breakdown.

Mature Compost: Generally suitable as an organic soil conditioner, but is only partially stabilized and may temporarily arrest plant growth if it comes in direct contact with the roots.

Cured Compost: Highly stabilized product, excellent organic soil conditioner.

Class A: Includes cured compost, suitable for lawn and garden application, referred to as designer compost.

Class B: Includes fresh and mature compost, used as an agronomic soil amendment

Analysis of Raw Materials

Wood chips 83.08 35.84 1.27
Grass 58.39 43.99 3.79
Leaves 77.75 48.02 1.37
Solid Manure 49.10 25.75 1.38
Liquid Manure .5072

Analysis of Mature Compost

pH %DM Ash %N %C C:N
7.6 64.43 67.31 1.75 18.16 11:17

Solid Livestock Waste

1.59 lbs. manure: 1 lb. landscape waste
652.0 lbs manure: 1 cu. yd. landscape waste
1.96 tons of raw material to make 1 ton compost

Swine Liquor-Grass

.20 lbs. liquid manure: 1 lb grass
135.59 lbs. liquid manure: 1 cu. yd. grass
1.82 tons raw material to make 1 ton of compost

Compost Process

No. of turns - 11
Days between turns - 5.2
Days from first to last turn - 53
Days to compost - 75

Swine Liquor - Wood Chips

3.19 lbs. liquid manure: 1 lb. wood chips
1592.59 lbs. liquid manure: 1 cu. yd. wood chips
5.78 tons of raw material to make 1 ton of compost

Swine Liquor - Wood Chips

3.19 lbs. liquid manure: 1 lb. wood chips
1592.59 lbs. liquid manure: 1 cu. yd. wood chips
5.78 tons of raw material to make 1 ton of compost

Compost Process

No. of turns - 16
Days between turns - 2.2
Days from first to last turn - 33
Days to compost - 151

Key Factors to Composting

  • Moisture Content
  • Temperature
  • Carbon to Nitrogen Ratio
  • Nutrient Balance
  • Aeration
  • pH
  • Substrate

Moisture content

  • Not less than 45%
  • Not more than 70%

Carbon to Nitrogen Ratio

  • Between 25:1 and 30:1


  • To speed up composting it is important to maintain aerobic conditions and proper temperatures within each windrow.

Windrows should be turned to accomplish this.

Windrow Turning Frequency:
First 3 - 5 Days: Turn Daily
Next 3 - 4 Weeks: Turn 2 - 3 Times/Week
Week 5 to End: Turn Once/Week

The Illinois EPA, Bureau of Land and Bureau of Water regulates composting and in some instances permits are required.

Compost Siting Regulations

Permits are not required if:

  • The site is located on the farm on which the compost is applied.
  • Appropriate setbacks are followed.
    • one-fourth mile from the nearest nonfarm residence
    • one-half mile from the nearest populated area
  • The site is protected from flooding.
  • The site does not discharge runoff.
  • The site is 200 feet from the nearest potable water.
  • The site is operated by the farmer who is not a partner or employee of a waste hauler or generator.

Permits are required:

  • For livestock operations larger than 1000 head, a National Pollution Discharge Elimination System Permit is needed.
  • If compost is sold, a siting permit is needed.
  • If livestock waste is combined with landscape waste and exceeds greater than 10 percent of the total volume, an EPA organic waste-composting permit is required.

Further Reading

- You can view the other articles in this series from SWEETA by clicking here.

January 2012
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