Title

Manure Composting Quick Guide

(NM2047, February 2022)
File
Summary

Take this quick guide to the compost piles and use it as a quick reference when you have questions about carbon to nitrogen ratios, calibrating a spreader or application rates.

Lead Author
Lead Author:
Mary A. Keena, NDSU Extension Specialist, Livestock Environmental Management
Other Authors

Chryseis Modderman, UMN Extension Educator, Manure Nutrient Management

Melissa L. Wilson, UMN Assistant Professor and Extension Specialist, Manure Management and Water Quality

Jeff Gale, NDSU Foster County Extension Agent, Agriculture and Natural Resources

Availability
Availability:
Available in print
Publication Sections

Characteristics of Successful Composting

Tractor and Compost Pile

 

Characteristic Reasonable Range Preferred Range
Particle size 1/16 to 4 inches 1/8 to 2 inches
Temperature 105 to 160⁰F 110 to 50⁰F
Moisture 40% to 65% 50% to 60%
Oxygen 5% to 20% 10% to 15%
C:N (carbon:nitrogen) 20:1 to 40:1 25:1 to 30:1

Source: On-Farm Composting Handbook, NRAES-54 (Rynk et al., 1992)

More information on these characteristics can be found in publication NM1478
(Keena, 2022)

 

Not enough carbon?

Use the table below to add carbon-rich materials to raise C:N

Pounds of bulk material needed to raise C:N to 30:1 (per 100 lb. of manure)

Material to add and its avg. C:N

Initial manure C:N

10:1

Pounds of material to add 

Initial manure C:N

15:1

Pounds of material to add 

Initial manure C:N

20:1

Pounds of material to add 

Initial manure C:N

25:1

Pounds of material to add 

Leaves (55:1)

415 

215

110

45

Straw, oat (60:1)

370

190

95

40

Straw, general (80:1)

295

150

75

30

Straw, wheat (125:1)

240

125

65

25

Sawdust (440:1)

195

100

50

20

Wood shavings (600:1)

190

100

50

20

Newsprint (625:1)

190

100

50

20

Example: If the manure has a C:N of 15:1, you will need to add 190 pounds of oat straw per 100 pounds of manure to bring the overall C:N up to the desired 30:1.

Source: On-Farm Composting Handbook, NRAES-54 (Rynk et al., 1992)

Too much carbon?

Use the table below to add nitrogen-rich materials to lower the C:N

Pounds of bulk material needed to raise C:N to 30:1 (per 100 lb. of manure)

Material to add and its avg. C:N

Initial manure C:N

35:1

Pounds of material to add 

Initial manure C:N

40:1

Pounds of material to add 

Initial manure C:N

45:1

Pounds of material to add 

Initial manure C:N

50:1

Pounds of material to add 

Grass clippings (17:1)

20

35

45

55

Hay, legume (16:1) 15 30 40 50
Hay, general (22:1) 40 70 95 115

Example: If the manure has a C:N of 40:1, you will need to add 35 pounds of grass clippings per 100 pounds of manure to bring the overall C:N down to the desired 30:1.

Source: On-Farm Composting Handbook, NRAES-54 (Rynk et al., 1992)

Calibrating a Manure Spreader

More details can be found in publication NM1418 Manure Spreader Calibration For Nutrient Management Planning (Keena, 2021)

Weight Method

Step 1

Pounds applied =
Weight of full spreader –
Weight of empty spreader

Step 2

Area applied =
Length of spread area (ft) x
Width of spread area (ft)

Step 3

Tons per acre =

[Pounds applied (step 1)]

[Area applied (step 2)]

x 21.8

Tarp Method

Step 1

Pounds applied =
Weight of full tarp and bucket – Weight of empty tarp & bucket

Step 2

Area of tarp =
Length of tarp (ft) x
Width of tarp (ft)

Step 3

Tons per acre =

[Pounds applied (step 1)]

[Area of tarp (step 2)]

x 21.8

Where does 21.8 come from?

To convert pounds per square feet to tons per acre, we need to multiply the weight in pounds by 43,560 square feet (= 1 acre) and divide that by 2,000 pounds (= 1 ton). To simplify this, we multiply by 21.8, which is 43,560/2,000.

Calculating Application Rates

Step 1

Determine P needs of the crop

Crop P needs = Expected yield x Crop P2O5 removal

Step 2

Determine Plant Available P (PAP) content of the compost

If the compost analysis reports phosphorus as “P”,
you can convert it to P2O5 by multiplying by 2.29

80% of total P is plant available

PAP = Total P2O5 content of compost (from compost analysis) x 0.80

Step 3

Calculate application rate

Application rate (in tons per acre) = Crop P needs (step 1) ÷ PAP (step 2)

Crop P Removal Rates

Crop

Yield Units

Crop P2O5 removal
(lb. per yield unit)

Alfalfa

Tons (air dry)

10.80

Barley (grain)

Tons (air dry)

0.41

Barley (grain and straw)

Bushels

0.55

Canola

Cwt.

1.30

Corn (grain)

Bushels

0.28

Corn (silage)

Tons (as fed)

3.80

Edible beans

Pounds

0.01

Grass or hay pasture

Tons (air dry)

8.90

Grass/legume

Tons (air dry)

11.20

Oats (grain)

Bushels

0.25

Oats (grain and straw)

Bushels

0.32

Peas

Pounds

0.01

Potatoes

Cwt.

0.14

Red Clover

Tons (air dry)

10.80

Rye (grain)

Bushels

0.44

Rye (grain and straw)

Bushels

0.59

Soybean

Bushels

0.82

Sugarbeets

Fresh Tons

0.73

Sunflower

Pounds

0.01

Sweet corn

Tons

11.00

Wheat (grain)

Bushels

0.53

Wheat (grain and straw)

Bushels

0.64

How much plant-available N has been applied?

10-15% of total N in compost is available the first year
(use 0.10 for cattle & lower-N compost, and 0.15 for poultry & higher-N compost)

Plant-available N =
Total N content of compost (from compost analysis) x .10 x application rate

References

Keena, M. A. 2022. Composting Animal Manures: A guide to the process and management of animal manure compost. North Dakota State University Cooperative Extension publication NM1478.

Keena, M. A. 2021. Manure Spreader Calibration for Nutrient Management Planning. North Dakota State University Cooperative Extension publication NM1478.

Rynk, R., M. van de Kamp, G. B. Willson, M. E. Singley, T. L. Richard, J. J. Kolega, Gouin, F. R., L. Laliberty, D. Kay, D. W. Murphy, H. A. J. Hoitink, W. F. Brinton. 1992. On-Farm Composting Handbook (NRAES 54). Northeast Regional Agricultural Engineering Service. Ithaca, New York.

Thank you to our reviewers: Lindy Berg, NDSU Extension, Towner County; Renae Gress, NDSU Extension, Morton County; Greg Klinger, UMN Extension, Water Resources Center; and Annie Klodd, UMN Extension, Farmington Regional Office

More information is available at ndsu.edu/agriculture/ag-hub.

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