| ... | ... | @@ -8,29 +8,27 @@ Indirect emissions are N<sub>2</sub>O emissions that are a secondary effect of a |
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According to [IPCC (2006)](/9-Literature#ipcc-intergovernmental-panel-on-climate-change-2006), indirect N<sub>2</sub>O emissions caused by the N management in animal housing and manure storage are attributed to animal husbandry (Sector 3.B), see Chapter [4.4.3](/4%20Manure%20management/4.4%20Greenhouse-gases/4.4.3%20indirect%20N2O%20from%20manure%20management). For indirect N<sub>2</sub>O emissions in connection with digestion of energy crops see also Chapter [4.4.3](/4-Manure-management/4.4-Greenhouse-gases/4.4.3-Indirect-N2O-from-manure-management#deposition). All other indirect N<sub>2</sub>O emissions are reported in the Sector 'agricultural soils' (Sector 3.D). Their calculation is described in the following.
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Table 1 gives an overview of the methodologies applied. Since submission 2024 a tier 2 method is applied to calculate indirect N<sub>2</sub>O emissions from leaching. For the emissions from deposition, only Tier 1 calculation procedures are available for the time being.
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Table 1 gives an overview of the methodologies applied. Since submission 2024 a tier 3 method is applied to calculate indirect N<sub>2</sub>O emissions from leaching. For the emissions from deposition, only Tier 1 calculation procedures are available for the time being.
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**Table 1: Agricultural soils, procedures used for the calculation of indirect N2O emissions**
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**Table 1: Agricultural soils, procedures used for the calculation of indirect N2O emissions** 
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# Leaching
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Nitrogen inputs into soils are to some extent liable to runoff and leaching. The inputs into surface and ground waters give rise to indirect nitrous oxide emissions.
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The indirect N2O emissions as a result of leaching and surface runoff are calculated using a Tier 3 method since submission 2024. The methodology is based on the calculation of nitrogen surpluses, a proportion of which is washed out as nitrate or laterally displaced into receiving waters in a region-specific manner. The N surpluses are formed from the sum of the N inputs (from mineral fertilizers, manure (domestic and imported), crop residues, digestion residues, sewage sludge and composts) minus the N withdrawal in the harvest and minus the nitrogen produced when mineral and organic fertilizers are applied as NH3 -is emitted. Eysholdt et al. (2022) have modeled what proportion of the N excess at the NUTS-2 level is washed out or flows off the surface. This proportion is assumed to be constant over the entire time series. The methodology is described in detail in Eysholdt et al. (2022).
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The indirect N2O emissions as a result of leaching and surface runoff are calculated using a Tier 3 method since submission 2024. The methodology is based on the calculation of nitrogen surpluses, a proportion of which is washed out as nitrate or laterally displaced into receiving waters in a region-specific manner. The N surpluses are formed from the sum of the N inputs (from mineral fertilizers, manure (domestic and imported), crop residues, digestion residues, sewage sludge and composts) minus the N withdrawal in the harvest and minus the nitrogen produced when mineral and organic fertilizers are applied as NH3 -is emitted. Eysholdt et al. (2022) have modeled what proportion of the N excess at the NUTS-2 level is washed out or flows off the surface. This proportion is assumed to be constant over the entire time series. The methodology is described in detail in [Eysholdt et al. (2022)](https://juser.fz-juelich.de/record/916954/files/Journal%20of%20Plant%20Nutrition%20and%20Soil%20Science%20-%202022%20-%20Eysholdt%20-%20A%20model%E2%80%90based%20estimate%20of%20nitrate%20leaching%20in%20Germany%20for.pdf).
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The indirect N2O emissions are calculated by multiplying the amount of N that is leached or flows off the surface with the N2O-N conversion factor 44/28, as well as the emission factor (0.011 kg N2O-N (kg N)-1, see IPCC (2019) ). Figure XX shows that the emissions resulting from the new method are significantly lower than with the previous Tier 1 method with constant FracLEACH.
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## Frac<sub>LEACH</sub>
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<span dir="">Frac<sub>LEACH</sub> is defined as the relative fraction of N inputs into the soil that is lost via leaching and surface runoff (Frac<sub>LEACH</sub> = m<sub>leach</sub>/m<sub>soil</sub>; for m<sub>leach</sub> and m<sub>soil</sub>, see below.</span>
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<span dir="">Frac<sub>LEACH</sub> is defined as the relative fraction of N inputs into the soil that is lost via leaching and surface runoff.</span>
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The [IPCC (2006)](/9-Literature#ipcc-intergovernmental-panel-on-climate-change-2006) default value for FracLEACH used to calculate emissions until submission 2023 is no longer used, but an implied national FracLEACH value is subsequently calculated.
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Since Submission 2024 Frac<sub>LEACH</sub> is calculated for each district and each year.
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## Activity data
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The amount of leached N (_m_<sub>leach</sub>) that leads to indirect N<sub>2</sub>O emissions is calculated by multiplying an amount of N (_m_<sub>N, </sub>see Equation below) with the leaching factor _Frac_<sub>leach</sub>. According to [IPCC (2006)](/9-Literature#ipcc-intergovernmental-panel-on-climate-change-2006)-11.24, Table 11.3, _Frac_<sub>leach</sub> = 0.3 kg kg<sup>-1</sup>. The criterion for the application of _Frac_<sub>leach</sub> = 0.3 kg kg<sup>-1</sup> is the exceedance of the soil water-holding capacity, see [IPCC (2006a)](/9-Literature#ipcc-intergovernmental-panel-on-climate-change-2006a)-11.24, Table 11.3. As there is groundwater recharge all over Germany ([Neumann & Wycisk, 2002](/9-Literature#neumann-j-wycisk-p-2002)) it can be assumed, on an annual basis, that soil water-holding capacity is exceeded in Germany.
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The amount of leached N (_m_<sub>leach</sub>) that leads to indirect N<sub>2</sub>O emissions is calculated by multiplying an amount of N (_m_<sub>N, </sub>see Equation below) with the leaching factor _Frac_<sub>leach</sub>.
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