Calculate indirect Nitrous Oxide (N2O) emissions from manure volatilization

Calculates daily indirect nitrous oxide (N2O) emissions resulting from atmospheric deposition of volatilised nitrogen (NH3–N and NOx–N) from manure management systems and separates emissions from manure deposited on pasture, manure burned for fuel, and all other manure management systems.

Usage

calc_n2o_manure_volatilization(
  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. Values ranges from 0 to 1. The sum of all fractions for each herd_id must equal 1.
n2o_ef4: Numeric. Emission factor for indirect nitrous oxide (N2O) emissions resulting from atmospheric deposition of volatilised nitrogen (NH3–N and NOx–N) onto soils and water surfaces (kg N2O–N per kg NH3–N + NOx–N). Default values can be selected from Table 11.3 in IPCC Guidelines (IPCC 2006, 2019).
nitrogen_fracgas: Numeric. Fraction of manure nitrogen excreted by a given livestock category that is lost through volatilisation as ammonia (NH3) and nitrogen oxides (NOx) within a specific manure management system. This parameter represents the share of excreted nitrogen that is mineralised and released to the atmosphere during manure collection, storage, and treatment. It is expressed as a dimensionless fraction (0–1). Default values are provided in Table 10.22 of 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_vol: Numeric. Indirect nitrous oxide (N2O) emissions resulting from atmospheric deposition of volatilised nitrogen (NH3 and NOx) from manure deposited on pasture (kg N2O/head/day).
n2o_manure_burned_vol: Numeric. Indirect nitrous oxide (N2O) emissions resulting from atmospheric deposition of volatilised nitrogen (NH3 and NOx) from manure burned for fuel (kg N2O/head/day).
n2o_manure_other_vol: Numeric. Indirect nitrous oxide (N2O) emissions resulting from atmospheric deposition of volatilised nitrogen (NH3 and NOx) from manure management systems, excluding manure deposited on pasture and manure burned for fuel (kg N2O/head/day).
n2o_manure_all_noburn_vol: Numeric. Indirect nitrous oxide (N2O) emissions resulting from atmospheric deposition of volatilised nitrogen (NH3 and NOx) from manure management systems, excluding losses from manure burned for fuel (kg N2O/head/day).

Details

This calculation follows the Tier 2 methodology for indirect N2O emissions from manure management as defined in the IPCC Guidelines in Equations 10.26 (IPCC, 2006, 2019), 10.27 (IPCC, 2006) and 10.28 (IPCC, 2019).

In the IPCC formulation, indirect emissions from atmospheric deposition of volatilised nitrogen are calculated as:

$$ N2O_{G(mm)} = \frac{44}{28} \sum_{S} \left( N \times AWMS_S \times FracGas_{S} \times EF4 \right) $$

where:

$N2O_G(mm)$: Indirect N2O emissions due to volatilization of N 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 $S$.
$FracGas_{S}$: Fraction of nitrogen volatilised as NH3–N and NOx–N in manure management system $S$.
$EF4$: Emission factor for indirect N2O emissions from atmospheric deposition (kg N2O-N per kg NH3–N + NOx–N).

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

$$ \begin{aligned} N_2O &= nitrogen\_excretion \times ratio\_N2ON\_to\_N2O \times \\ & \sum_{S} \left( manure\_management\_system\_fraction \times nitrogen\_fracgas \times n2o\_ef4 \right) \end{aligned} $$

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 10.26; 10.28.

IPCC. (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management. Equation 10.26; 10.27.

Examples

calc_n2o_manure_volatilization(
  ratio_N2ON_to_N2O = 44 / 28,
  nitrogen_excretion = 0.9,
  mms_burned = c(
    manure_management_system_fraction = 0.020,
    n2o_ef4 = 0.14,
    nitrogen_fracgas = 0
  ),
  mms_drylot = c(
    manure_management_system_fraction = 0.264,
    n2o_ef4 = 0.14,
    nitrogen_fracgas = 0.3
  ),
  mms_pasture = c(
    manure_management_system_fraction = 0.310,
    n2o_ef4 = 0.14,
    nitrogen_fracgas = 0.21
  ),
  mms_solid = c(
    manure_management_system_fraction = 0.406,
    n2o_ef4 = 0.14,
    nitrogen_fracgas = 0.45
  )
)
#> $n2o_manure_pasture_vol
#> [1] 0.0128898
#> 
#> $n2o_manure_burned_vol
#> [1] 0
#> 
#> $n2o_manure_other_vol
#> [1] 0.0518562
#> 
#> $n2o_manure_all_noburn_vol
#> [1] 0.064746
#>