Calculate direct Nitrous Oxide (N2O) emissions from manure management systems

Calculates daily direct nitrous oxide (N2O) emissions from manure management using IPCC-based parameters and separates emissions from manure deposited on pasture, manure burned for fuel, and all other manure management systems.

Usage

calc_n2o_manure_direct(ratio_N2ON_to_N2O = 44/28, nitrogen_excretion, ...)

Arguments

ratio_N2ON_to_N2O

Numeric. Conversion factor from kg N2O–N to kg N2O, based on molecular weights. Defaults to 44/28.

nitrogen_excretion

Numeric. Daily nitrogen excretion (kg N/head/day).

...

A variable number of manure management system (MMS) arguments. Each MMS must be provided as a named numeric vector with exactly the following fields:

manure_management_system_fraction: Numeric. Fraction of total manure excreted by animals in a given herd and cohort that is handled in a specific manure management system. Value ranges from 0 to 1. The sum of all fractions for each herd_id must equal 1.
n2o_ef3: Numeric. Emission factor for direct nitrous oxide (N2O) emissions for each manure management system, representing nitrous oxide emitted per unit of nitrogen from nitrification and denitrification processes occurring during manure storage and treatment (kg N2O–N per kg N). Default values may be selected from Table 10.21 and Table 11.1 (for manure deposited on pasture) in IPCC Guidelines (IPCC 2006, 2019).

Two MMS names are treated explicitly when present:

mms_pasture: Manure deposited on pasture.
mms_burned: Manure burned for fuel.

All remaining MMS arguments are grouped and treated as other manure management systems.

Value

A named list with the following elements:

n2o_manure_pasture_direct: Numeric. Direct nitrous oxide (N2O) emissions from manure deposited on pasture (kg N2O/head/day).
n2o_manure_burned_direct: Numeric. Direct nitrous oxide (N2O) emissions from manure burned for fuel (kg N2O/head/day).
n2o_manure_other_direct: Numeric. Direct nitrous oxide (N2O) emissions from manure management systems, excluding emissions from manure deposited on pasture and burned for fuel (kg N2O/head/day).
n2o_manure_all_noburn_direct: Numeric. Direct nitrous oxide (N2O) emissions from manure management systems, excluding manure burned for fuel (kg N2O/head/day).

Details

This calculation follows the Tier 2 methodology for direct nitrous oxide (N2O) emissions from manure management as defined in the IPCC Guidelines (Equation 10.25).

In the IPCC formulation, annual direct emissions are:

$$ N2O_{D(mm)} = \frac{44}{28} \sum_{S} \left( N \times AWMS_S \times EF3_S \right) $$

where:

$N2O_D(mm)$: Direct N2O emissions from Manure Management.
$44/28$: Conversion factor from N2O–N to N2O.
$N$: Nitrogen excreted (kg N).
$AWMS_S$: Fraction of excreted nitrogen managed in manure management system $S$.
$EF3_S$: Direct emission factor for system $S$ (kg N2O–N per kg N managed).

In this implementation, calculations are performed at daily, per-head resolution using nitrogen_excretion (kg N/head/day) - see also calc_nitrogen_excretion.

Daily emissions are computed as:

$$ \begin{aligned} N2O &= nitrogen\_excretion \times ratio\_N2ON\_to\_N2O \times \\ & \sum \left( manure\_management\_system\_fraction \times n2o\_ef3 \right) \end{aligned} $$

This function is part of the run_emissions_manure_module().

References

IPCC. (2019). 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management. Equation 10.25.

IPCC. (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management. Equation 10.25.

Examples

calc_n2o_manure_direct(
  ratio_N2ON_to_N2O = 44 / 28,
  nitrogen_excretion = 0.9,
  mms_burned = c(
    manure_management_system_fraction = 0.020,
    n2o_ef3  = 0
  ),
  mms_drylot = c(
    manure_management_system_fraction = 0.264,
    n2o_ef3  = 0.02
  ),
  mms_pasture = c(
    manure_management_system_fraction = 0.310,
    n2o_ef3  = 0.02
  ),
  mms_solid = c(
    manure_management_system_fraction = 0.406,
    n2o_ef3  = 0.005
  )
)
#> $n2o_manure_pasture_direct
#> [1] 0.008768571
#> 
#> $n2o_manure_burned_direct
#> [1] 0
#> 
#> $n2o_manure_other_direct
#> [1] 0.01033843
#> 
#> $n2o_manure_all_noburn_direct
#> [1] 0.019107
#>