IPCC Volume 4 Chapter 10 · Scope 1
Livestock: enteric fermentation and manure
Methane from digestion and from stored manure, and nitrous oxide from manure management. The first two are factors per animal; the third depends on how the farm handles manure, so it's a method.
On this page you'll learn
- Why head count means an average over the year
- How manure N₂O is calculated, and what the farm must supply
- Which species have only half the chapter
- Scope
- 1
- Publisher
- IPCC 2006 Vol 4 Ch 10
- Category codes
livestock_enteric_fermentation,livestock_manure_management- Basis
- Head-year (average population over the year)
Enteric fermentation and manure methane
IPCC's Equation 10.19 divides by 10⁶ to give gigagrams for national reporting. An organisation reporting in kilograms doesn't, and Slate doesn't: applying it would divide every farm's methane by a million while still producing a number.
Head count is an average
100 cattle kept for six months is 50 head-years. Unlike every other category, head count never falls back to the record's quantity column, because a spreadsheet import usually fills that with a count on one day, which would double the answer while looking ordinary.
Cattle factors are published by region, and the selection is matched exactly, never inferred. Poultry and two swine splits have manure factors but no enteric one ("insufficient data"); deer and alpacas are the reverse. Slate refuses the missing half at entry instead of letting it fail later.
Manure N₂O
- N_T
- head of livestock type T
- Nex_T
- nitrogen excreted per head per year (Eq 10.30)
- MS_T,S
- share of manure handled in system S, supplied by the farm
- EF3_S
- N₂O-N per kg N for system S
EF3 runs from 0.001 (poultry manure with litter) to 0.1 (intensive windrow composting): a hundredfold spread that belongs to the farm's equipment, not the animal. That's why there's no per-head N₂O factor, and why the manure management split comes from the farm rather than IPCC's national averages.
Pasture, paddock, range
No EF3 here: IPCC counts that nitrogen under managed soils. Slate refuses it with the destination named, rather than recording zero.
Burned dung
Counted under Energy or Waste, also refused here.
Daily spread, uncovered lagoon, digester
Published EF3 = 0. Stored and calculated as zero, and the nitrogen still appears as an input for managed soils.
Animal mass
No default. Most rows are per 1,000 kg of animal per day; mink, rabbits and foxes are already per head per year, and running the mass formula over a rabbit overstates it 730 times.
Note
Indirect manure N₂O (volatilisation and leaching, Equations 10.26–10.28) is not implemented yet. Without the manure split, N₂O is recorded as unquantified and flagged as something you can supply.