3. Livestock & Manure Management

Livestock types and numbers

Manure management systems

In Miterra, four types of manure management systems (MMS) are defined:

Housing
Farmyard
Storage: the storage of manure in unconfined piles/stacks, or in tanks/ponds/lagoons, typically for a period of several months to less than a year, before the manure may be applied to the field as fertilisers;
Grazing: the dung and urine deposited directly to the soil by grazing animals during grazing period.

The fractions of N excretions in each MMS (f_{housing/yard/grazing}) are derivd from IPCC NIRs ( Greenhouse Gas Inventory Data - Flexible queries Annex I Parties).

For each MMS, livestock excretions are handled in both solid and liquid forms. The respective fractions of solid and liquid manure are determined by a predefined liquid-solid manure collection parameter (f_liquid), which is specific to region and animal type.

$animal fractions$

Figure 3.1: Split of housing/grazing hours and animal excretions.

N content in livestock excretion

N content in livestock excretion is calculated for each type of animal and each type of excretion (solid or liquid):

Equation 3.1

where:

	is the average amount of N in excretion that a single animal produces in one year (kg N head^–1 year^–1).
	is the fraction of N excreted during housing, farmyard, or grazing period.
	is the fraction of solid or liquid manure collected for the livestock in a region.

CH₄ emissions

CH₄ emissions originates from enteric fermentations, and manure methanogenesis during manure storage, and are calculated on the basis of animal numbers.

Equation 3.2