When I spread farmyard manure on a field, how much of its nitrogen does the Intergovernmental Panel on Climate Change count as lost to the air, compared with urea?

Table 11.3 of the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines assumes 20% of organic nitrogen applied is lost as ammonia and nitrogen oxides, against 10% of synthetic fertiliser nitrogen. At 0.010 for nitrous oxide, manure doubles the ammonia route of indirect nitrous oxide per kilogram of nitrogen; the leaching route, where it applies, is the same for both.

The factors (Table 11.3)

• FracGASF, synthetic fertiliser: 0.10 kilograms (kg) of nitrogen volatilised per kg applied (range 0.03 to 0.3).
• FracGASM, all organic nitrogen fertilisers applied, and dung and urine deposited by grazing animals: 0.20 (range 0.05 to 0.5).
• EF4, nitrous oxide nitrogen per kg of volatilised nitrogen: 0.010 (range 0.002 to 0.05).

The equation

Equation 11.9: nitrous oxide (N2O) nitrogen from volatilised nitrogen = [synthetic nitrogen x 0.10 + (organic nitrogen + grazing deposits) x 0.20] x 0.010. Multiply by 44/28 for N2O.

What it means for a switch from urea

The answer on manure against urea compares direct nitrous oxide only and says organic nitrogen loses a larger share to the air. This is the number behind that line. Per kilogram of nitrogen, manure carries twice the ammonia-route indirect nitrous oxide of urea in this table, which eats into the direct saving. Show the comparison as separate lines: direct, indirect and urea carbon dioxide. The leaching route, where it applies, is the same for both forms.

Which edition: this answer uses the 2006 table, the same one the urea answers use. The manure page quotes direct factors from the 2019 Refinement. Do not mix editions inside one comparison; pick one and say which.

Records to keep

• Kilograms of nitrogen applied by form, per plot and date. For manure, the tested or stated nitrogen content of the load.
• Grazing nitrogen, if animals feed on the plot, is added to the organic term.

100 kg of nitrogen applied, urea against farmyard manure

• Urea, ammonia route: 100 x 0.10 = 10 kg volatilised x 0.010 = 0.100 kg N2O nitrogen x 44/28 = 0.157 kg N2O x 273 = about 42.9 kg carbon dioxide equivalent (CO2e)
• Manure, ammonia route: 100 x 0.20 = 20 kg volatilised x 0.010 = 0.200 kg N2O nitrogen x 44/28 = 0.314 kg N2O x 273 = about 85.8 kg CO2e
• Difference: about 42.9 kg CO2e more ammonia-route indirect N2O for the manure

The 100 kg of nitrogen is an example value, with the same nitrogen applied in each form. 273 is the Sixth Assessment Report (AR6) 100-year warming potential for N2O. Direct nitrous oxide and urea carbon dioxide are separate lines.

What Senseible does here

Senseible reads fuel invoices and electricity bills into emission records, so diesel for tractors and power for irrigation pumps show up once uploaded. The fertiliser, residue and field figures on this page come from your own farm records.

• Manure against urea: nitrous oxide
• Fertiliser nitrous oxide calculation
• Ammonia loss from stored dairy manure

Sources: IPCC 2006 Guidelines, Volume 4, Chapter 11, Equation 11.9 and Table 11.3, IPCC Sixth Assessment Report, Working Group I, Chapter 7, Table 7.15 (100-year global warming potential: methane of non-fossil origin 27.0, nitrous oxide 273)

Last reviewed 2026-11-05. Factors are from the 2006 edition. The organic-manure page uses 2019 direct factors; keep one edition per comparison.