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Nitrogen module(51_nitrogen)

Description

This module calculates nitrogen dynamics and $N_2O$ emissions.
Nitrogen emissions before technical mitigation ($vm\_btm$) are then handed on the 57_maccs module to calculate emissions after technical mitigation.

Interfaces

Input

Name Description Unit A B
$vm\_prod\_reg(i,k)$ regional aggregated production mio. ton DM x
$vm\_land(j,land,si)$ areas of the different land types mio.ha x
$vm\_prod\_res\_ag\_reg(i,kve)$ production of aboveground residues in each region mio. ton DM x
$vm\_prod\_res\_bg\_reg(i,kve)$ production of belowground residues in each region mio. ton DM x
$vm\_res\_supply(i,res\_use,kve)$ use of residues for different purposes - x
$vm\_area(j,kcr,w)$ agricultural production area mio. ha x
$vm\_manure\_cropland(i,npk)$ manure nutrients recycled to cropland Mt Nr x
$vm\_btm\_reg(i,emis\_reg)$ emissions before technical mitigation Tg N2O-N CH4 and CO2-C x x
$pm\_land\_start(j,land)$ landpools from initialization mio. ha x
$im\_attributes\_harvest(attributes,kve)$ attributes of harvested organs t DM WM Nr P K GJ per ton product x
$fm\_attributes\_residue\_ag(attributes,kve)$ nutrient content of aboveground crop residues t nutrient per t DM x
$fm\_carbon\_density(t\_all,j,land,c\_pools)$ LPJ carbon density for land and carbon pools tC per ha x
$fm\_seed\_shr(i,k)$ seed share relative to production % x
$fm\_ipcc\_ef(ipcc\_ef,emis\_uncertainty)$ ipcc emission factors - x
$sm\_years$ length of current time step years x

The last columns of the table indicate the usage in the different realizations (numbered with capital letters)

Output

Name Description Unit
$vm\_nr\_inorg\_fert\_costs(i)$ inorganic fertilizer costs (module emissions) mio. $US

Interface plot


Figure 0: Information exchange among modules

Realizations

(A) off

No $N_2O$ emissions are calculated:

\begin{equation}
vm\_nr\_inorg\_fert\_costs.lo(i) = 0
\end{equation}

\begin{equation}
vm\_btm\_reg.fx(i,emis\_n2o) = 0
\end{equation}

Limitations
lower bound of $vm\_inorg\_fert\_costs$ is set to 0
$vm\_btm\_reg$ is fixed to 0

(B) july14 (default)

Calculates nitrogen cycle dynamics and N2O emissions.

A detailed description of this module and of underlying data sources can be found in [Bodirsky, B. L. et al.[1] (2012)].

The main constraint of the nitrogen module is the cropland nutrient balance. Nitrogen withdrawals from soils (right side of the equation) have to be balanced out by nitrogen inputs (left side of the equation). Since not all nitrogen inputs are incorporated into the plant, nitrogen inputs are multiplied with an exogenous soil nitrogen uptake efficiency ($v51\_nr\_eff$), which is equivalent to the share of soil nitrogen inputs that are taken up by plant roots. Nitrogen inputs include (in the order of appearance in the equation 1) aboveground (AG) crop residues recycled to the soils, the uncombusted remainders of crop resides that were burned on the field, belowground crop residues, fixation by free-living bacteria, manure excreted by animals that are grazing on croplands (see 55_awms), manure excreted in confinements and recycled to cropland soils (see 55_awms), inorganic fertilizer, soil organic matter lost after the conversion of pasture or natural vegetation to cropland, and atmospheric deposition. Nitrogen withdrawals are estimated as the nitrogen within harvested organs, aboveground crop residues, and belowground crop residues, minus the amount of nitrogen which is biologically fixed within the plant, and minus the amount of nitrogen in seeds. Nitrogen from biological fixation is estimated based on typical crop-specific shares of nitrogen derived from atmospheric fixation ("ndfa").

Equation 1:

\begin{align}
& v51\_nr\_eff(i) * (\sum_{kcr} vm\_res\_supply(i,\text{"$recycle$"},kcr) * fm\_attributes\_residue\_ag(\text{"$nr$"},kcr)) \\
& + \sum_{kcr} vm\_res\_supply(i,\text{"$burn$"},kcr) * (1-f51\_res\_combust\_eff(kcr)) * fm\_attributes\_residue\_ag(\text{"$nr$"},kcr))\\
& + \sum_{kcr} vm\_prod\_res\_bg\_reg(i,kcr) * f51\_nr\_residue\_bg(kcr)) \\
& + \sum_{cell(i,j)} \sum_{kcr,w} vm\_area(j,kcr,w) * f51\_nr\_fix\_area(kcr)) \\
& + vm\_manure\_cropland(i,\text{"$nr$"}) \\
& + v51\_nr\_inorg\_fert\_reg(i) \\
& + pc51\_nr\_som\_usable(i) \\
& + v51\_nr\_dep\_crop(i)) \\
& \ge \\
& \sum_{kcr} (1-f51\_nr\_fix\_ndfa(i,kcr)) * ( vm\_prod\_reg(i,kcr)* im\_attributes\_harvest(\text{"$nr$"},kcr) \\
& + vm\_prod\_res\_ag\_reg(i,kcr)*fm\_attributes\_residue\_ag(\text{"$nr$"},kcr) \\
& + vm\_prod\_res\_bg\_reg(i,kcr)*f51\_nr\_residue\_bg(kcr)) \\
& - vm\_prod\_reg(i,kcr) * fm\_seed\_shr(i,kcr) * im\_attributes\_harvest(\text{"$nr$"},kcr))
\end{align}

The consumption of inorganic fertilizers (equation 2) is connected to costs that enter the goal function:

Equation 2:

\begin{equation}
vm\_nr\_inorg\_fert\_costs(i) =
v51\_nr\_inorg\_fert\_reg(i) * f51\_inorg\_fert\_costs\_1995(i,\text{"$nr$"})
\end{equation}

Atmospheric nitrogen deposition is currently deactivated in the nitrogen module.

Equation 3:

\begin{equation}
v51\_nr\_dep\_crop(i) = 0
\end{equation}

$N_2O$ emissions are estimated based on the IPCC Guidelines for National Greenhouse Gas Inventories [IPCC2] (2006)].
They include emissions from inorganic fertilizers, crop residues, manure applied to croplands, manure excreted to pastures, animal waste management and soil organic matter loss. As rice has a lower emission factor than other crops, but as our method does not distinguish which fertilizer is applied to which crop, the (negative) emission bonus for rice is calculated separately.

Equation 4:

\begin{align}
vm\_btm\_reg(i,\text{"$inorg\_fert\_n2o$"}) & = v51\_nr\_inorg\_fert\_reg(i) * ( fm\_ipcc\_ef(\text{"$ef\_1$"},\text{"$best$"})\\
& + fm\_ipcc\_ef(\text{"$frac\_gasf$"},\text{"$best$"}) * fm\_ipcc\_ef(\text{"$ef\_4$"},\text{"$best$"}) \\
& + fm\_ipcc\_ef(\text{"$frac\_leach\_h$"},\text{"$best$"}) * fm\_ipcc\_ef(\text{"$ef\_5$"},\text{"$best$"}))
\end{align}

Equation 5:

\begin{align}
vm\_btm\_reg(i,\text{"$resid\_n2o$"}) & = \sum_{kcr} vm\_res\_supply(i,\text{"$recycle$"},kcr)*fm\_attributes\_residue\_ag(\text{"$nr$"},kcr) \\
& + vm\_res\_supply(i,\text{"$burn$"},kcr)*(1-f51\_res\_combust\_eff(kcr))*fm\_attributes\_residue\_ag(\text{"$nr$"},kcr) \\
& + vm\_prod\_res\_bg\_reg(i,kcr) * f51\_nr\_residue\_bg(kcr)) \\
& * ( fm\_ipcc\_ef(\text{"$ef\_1$"},\text{"$best$"}) + fm\_ipcc\_ef(\text{"$frac\_leach\_h$"},\text{"$best$"}) * fm\_ipcc\_ef(\text{"$ef\_5$"},\text{"$best$"}))
\end{align}

Equation 6:

\begin{align}
vm\_btm\_reg(i,\text{"$som\_n2o$"}) & = pc51\_nr\_som(i) * ( fm\_ipcc\_ef(\text{"$ef\_1$"},\text{"$best$"}) \\
& + fm\_ipcc\_ef(\text{"$frac\_leach\_h$"},\text{"$best$"}) * fm\_ipcc\_ef(\text{"$ef\_5$"},\text{"$best$"}))
\end{align}

Equation 7:

\begin{align}
vm\_btm\_reg(i,\text{"$rice\_bonus\_n2o$"}) & = - vm\_prod\_reg(i,\text{"$rice\_pro$"}) \\
& * im\_attributes\_harvest(\text{"$nr$"},\text{"$rice\_pro$"})/v51\_nr\_eff(i) \\
& *(fm\_ipcc\_ef(\text{"$ef\_1$"},\text{"$best$"}) - fm\_ipcc\_ef(\text{"$ef\_1fr$"},\text{"$best$"}))
\end{align}

Limitations
atmospheric nitrogen deposition is currently not considered.

Definitions

Name Description Unit A B
$ic51\_years$ time between previous and current time step years x
$sc51\_t$ current timestep - x
$p51\_netexpansion(t,j)$ positive expansion of cropland mio ha x
$p51\_nr\_release(t,j)$ release of nitrogen Tg per mio ha x
$p51\_nr\_som(t,j)$ Nr released by soil organic matter loss Tg Nr x
$p51\_nr\_som\_usable(t,j)$ Nr released by soil organic matter loss that can be aquired by cropping activities Tg Nr x
$p51\_land\_crop\_before(j)$ area of cropland pool in last timestep mio. ha x
$i51\_nr\_dep\_ha\_1995(i)$ Nr deposition rates on croplands t Nr per ha x
$p51\_volat\_cropl\_ha(t,i)$ volatilisation on croplands due to manure and fertilizer application t NHx and NOy per ha x
$p51\_volat\_cropl\_ha\_1995(i)$ volatilisation on croplands due to manure and fertilizer application t NHx and NOy per ha x
$i51\_nr\_eff(t,i)$ selected scenario values for nr efficiency - x
$pc51\_nr\_som(i)$ nr release from soil organic matter in last timestep Tg Nr x
$pc51\_nr\_som\_usable(i)$ nr release from soil organic matter in last timestep usable for crop production Tg Nr x
$i51\_n\_content\_kli(kli)$ nitrogen content of animal products (used for feed) - x
$i51\_heads\_per\_kli(t,i,kli,lvst)$ animal heads per livestock unit heads per ton x
$i51\_nex(t,i,lvst)$ nitrogen excretion per livestock type ton per head x
$i51\_heads\_per\_kli\_1995(i,kli,lvst)$ animal heads per livestock unit in 1995 heads per ton x
$i51\_nex\_1995(i,lvst)$ nitrogen excretion per livestock type in 1995 ton per head x
$i51\_recycl\_conf(t,i,kli)$ share of nutrients in confinement returned to field % x
$ic51\_recycl\_conf(i,kli)$ timesteps share of nutrients in confinement returned to field % x
$i51\_animal\_shr\_awms(t,i,kli,awms)$ share of animals managed under a specific awms % x
$ic51\_animal\_shr\_awms(i,kli,awms)$ timesteps share of animals managed under a specific awms % x
$i51\_manure\_fuel\_shr(t,i,kli)$ share of manure on pasture collected for household fuel % x
$ic51\_manure\_fuel\_shr(i,kli)$ timestep share of manure on pasture collected for household fuel % x
$i51\_conf\_to\_cropl\_shr(t,i)$ share of manure-N in confinements applied to croplands % x
$ic51\_conf\_to\_cropl\_shr(i)$ timestep share of manure-N in confinements applied to croplands % x
$i51\_feedres\_to\_cropl\_shr(t,i)$ share of cropland residues used as feed eaten on croplands (as opposed to eaten in confinement) % x
$ic51\_feedres\_to\_cropl\_shr(i)$ timestep share of cropland residues used as feed eaten on croplands (as opposed to eaten in confinement) % x
$i51\_manure\_conf\_distribution(t,i,kli,awms\_conf)$ share of confined manure distributed to different awms_conf % x
$i51\_ipcc\_ms\_awms(t,i,lvst,awms)$ fraction of livestock type managed under which feeding system % x
$i51\_ipcc\_ef3\_prp(t,i,kli)$ mixture of emission factor 3 according to distribution of sheep goats etc within category - x
$ic51\_ipcc\_ef3\_prp(i,kli)$ mixture of emission factor 3 according to distribution of sheep goats etc within category - x
$i51\_conf\_direct\_emis(t,i,kli)$ share of direct emissions in the form of N2O-N % x
$ic51\_conf\_direct\_emis(i,kli)$ share of direct emissions in the form of N2O-N % x
$i51\_conf\_loss\_gas(t,i,kli)$ share of nutrients volatilized per kli % x
$ic51\_conf\_loss\_gas(i,kli)$ timestep share of nutrients volatilized per kli % x
$v51\_nr\_inorg\_fert\_reg(i)$ inorganic fertilizer application Tg Nutrients x
$v51\_nr\_eff(i)$ cropland nitrogen uptake efficiency % x
$v51\_nr\_dep\_crop(i)$ atmospheric deposition on cropland t Nr x
$f51\_inorg\_fert\_reg\_1995(i,npk)$ inorganic industrial fertilizer in 1995 Mt Nutrient x
$f51\_inorg\_fert\_costs\_1995(i,npk)$ inorganic industrial fertilizer in 1995 Mt Nutrient x
$f51\_nr\_som\_1995(i)$ nitrogen by soil organic matter loss in 1995 Tg Nr x
$f51\_n\_dep\_ha(t\_all,i)$ nitrogen by atmospheric deposition on croplands ton N per ha x
$f51\_n\_i\_dep\_past(t\_all,i)$ nitrogen by atmospheric deposition on pastureland ton N per ton yield x
$f51\_nr\_fix\_ndfa(i,kve)$ Nr fixation rates per ton production % of plant DM x
$f51\_nr\_fix\_area(kve)$ Nr fixation rates per area ton per ha x
$f51\_nr\_residue\_bg(kve)$ nitrogen content of belogwround residues % x
$f51\_res\_combust\_eff(kve)$ combustion efficiency of residue burning % x
$f51\_nr\_eff(t_all,i)$ selected scenario values for Nr efficiency - x

The last columns of the table indicate the usage in the different realizations (numbered with capital letters)

Developer(s)

Benjamin Leon Bodirsky

See Also

Overview, 57_maccs, 55_awms

References

1 [Bodirsky, B. L. et al. (2012)] Bodirsky, B. L. et al. (2012) N2O emissions from the global agricultural nitrogen cycle – current state and future scenarios. Biogeosciences 9, 4169–4197.

2 [IPCC (2006)] IPCC (2006) Guidelines for National Greenhouse Gas Inventories, Prepared by the National Greenhouse Gas Inventories Programme, Institute for Global Environmental Strategies, Kanagawa, Japan.