Which manure storage systems on a dairy farm give off nitrous oxide under the Intergovernmental Panel on Climate Change Tier 1 method, and how much per kilogram of nitrogen?
Table 10.21 gives a factor per kilogram (kg) of nitrogen excreted: 0 for daily spreading, slurry without a crust and lagoons, 0.005 for solid storage, 0.02 for a dry lot, and 0.1 for intensively turned compost windrows. Multiply by the nitrogen in each system, then by 44/28 and the warming potential.
The equation
Equation 10.25 of the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines, Volume 4: nitrous oxide nitrogen (N2O-N) = the sum, over each system, of head count x annual nitrogen excreted per head x the share managed in that system x the emission factor (EF3) for that system. Multiply by 44/28 to get nitrous oxide (N2O). The nitrogen per head is in the answer linked below.
Direct factors, kg of N2O-N per kg of nitrogen excreted (Table 10.21)
- Slurry without crust, uncovered lagoon, digester: 0. The guide calls these negligible because no oxidised nitrogen enters and nitrification and denitrification are unlikely.
- Daily spread: 0. The guide assumes zero during storage and treatment because the manure is applied within 24 hours; the field emission is counted under managed soils.
- Pit storage below animal confinements: 0.002.
- Solid storage and liquid or slurry with natural crust cover: 0.005.
- Dry lot: 0.02.
- Cattle and swine deep bedding: 0.01 with no mixing and 0.07 with active mixing.
- Composting: 0.006 in-vessel and static pile, 0.01 passive windrow, 0.1 intensive windrow.
- Poultry manure with or without litter: 0.001.
- Uncertainty is shown as a factor of 2 for the non-zero factors, which the chapter text states as minus 50 to plus 100 per cent.
What is counted elsewhere
- Manure left on pasture, range or paddock, and manure applied to fields, is counted under managed soils in Chapter 11, not here.
- Burned dung cakes are reported under Fuel Combustion or Waste Incineration, not here.
- Ammonia lost from the stored manure is a separate indirect line, covered in the answer on ammonia loss and indirect nitrous oxide.
A farm point worth checking
The intensive windrow factor, 0.1, is twenty times the solid storage factor. If a farm turns its heap often to make compost faster, it falls under intensive windrow (0.1). Infrequent turning is passive windrow (0.01). A heap left alone is solid storage (0.005). The guide says intensive windrow emissions are a function of turning frequency. Composting of food waste, rather than manure, sits in a different volume; see the composting answer linked below.
100 dairy cows, 4,718 kg of nitrogen a year, all in one system
- Solid storage: 4,718 x 0.005 = 23.6 kg N2O-N x 44/28 = 37.1 kg N2O x 273 = about 10,100 kg carbon dioxide equivalent (CO2e)
- Dry lot: 4,718 x 0.02 = 94.4 kg N2O-N x 44/28 = 148.3 kg N2O x 273 = about 40,500 kg CO2e
- Intensive windrow: 4,718 x 0.1 = 471.8 kg N2O-N x 44/28 = 741.4 kg N2O x 273 = about 202,400 kg CO2e
- Slurry without crust: 4,718 x 0 = 0
One system for the whole herd is an example scenario. 273 is the Sixth Assessment Report (AR6) 100-year warming potential for N2O. A zero factor here does not mean zero methane; slurry has high methane.
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
- Ammonia loss and indirect nitrous oxide
- Composting and digester default factors
- Tier 2 manure methane: slurry or dry
Sources: IPCC 2006 Guidelines, Volume 4, Chapter 10, Equation 10.25 and Table 10.21, 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 2006 Tier 1 defaults with a wide printed range. Use measured or country-specific factors if your buyer or verifier accepts them.