How much of the nitrogen in dairy manure is lost to the air as ammonia, and how does the Intergovernmental Panel on Climate Change turn that into nitrous oxide?

Table 10.22 of the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines gives the share of nitrogen lost as ammonia and nitrogen oxides: for dairy cows 30% in solid storage, 20% in a dry lot and 7% when spread daily. Multiply the lost nitrogen by 0.010 and 44/28 to get nitrous oxide (N2O).

The two steps

1. Nitrogen lost = head count x annual nitrogen excreted per head x the share in each system x the loss percentage for that system divided by 100 (Equation 10.26).
2. N2O nitrogen = nitrogen lost x EF4, where EF4 is 0.010 kilograms (kg) of N2O nitrogen per kg of ammonia and nitrogen oxide nitrogen lost (Equation 10.27 and Table 11.3). Multiply by 44/28 to get N2O.

Loss percentages for cattle (Table 10.22)

• Dairy cow: anaerobic lagoon 35%, liquid or slurry 40%, pit storage 28%, dry lot 20%, solid storage 30%, daily spread 7%.
• Other cattle: dry lot 30%, solid storage 45%, deep bedding 30%.
• The ranges printed in the table are wide. For dairy cow daily spread the range is 5 to 60%, and for solid storage 10 to 40%.
• The table covers losses at housing and at the final storage.

What this does to the nitrogen left for the field

Nitrogen lost in storage is no longer available to spread. The guide separates it with its total nitrogen loss values in Table 10.23 (for example 40% for dairy cow solid storage and 22% for daily spread), which cover ammonia, nitrogen oxides, nitrous oxide and nitrogen gas losses plus leaching and runoff from solid storage and dry lots, for typical systems without significant nitrogen control measures, and takes managed manure nitrogen available for soils from those. The guide says all nitrogen losses from manure systems, direct and indirect, need to be excluded from the manure nitrogen reported as applied to soils.

Leaching from storage

The guide says estimating nitrogen lost to leaching and runoff from manure systems should be part of a Tier 2 or Tier 3 method, because default data are extremely limited. At Tier 1 only the ammonia route above is calculated.

100 dairy cows, 4,718 kg of nitrogen a year, all in one system

• Solid storage: 4,718 x 30% = 1,415 kg nitrogen lost x 0.010 = 14.15 kg N2O nitrogen x 44/28 = 22.2 kg N2O x 273 = about 6,072 kg carbon dioxide equivalent (CO2e)
• Daily spread: 4,718 x 7% = 330 kg nitrogen lost x 0.010 = 3.30 kg N2O nitrogen x 44/28 = 5.2 kg N2O x 273 = about 1,417 kg CO2e
• Dry lot: 4,718 x 20% = 944 kg nitrogen lost x 0.010 = 9.44 kg N2O nitrogen x 44/28 = 14.8 kg N2O x 273 = about 4,048 kg CO2e

One system for the whole herd is an example scenario. 273 is the Sixth Assessment Report (AR6) 100-year warming potential for N2O. Direct N2O from the stored manure is a separate line.

What Senseible does here

Senseible reads fuel invoices and electricity bills into emission records, so diesel for tractors and pumps and power for the milking shed and chilling tank show up once uploaded. The herd, manure and field figures on this page come from your own farm records.

• Nitrogen excreted per cow and buffalo
• Nitrous oxide from manure storage
• Farmyard manure ammonia loss on the field

Sources: IPCC 2006 Guidelines, Volume 4, Chapter 10, Equations 10.26 and 10.27, Tables 10.22 and 10.23, and Chapter 11 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. Loss percentages are 2006 defaults. Measured ammonia losses replace them where you have data.