3.D - Agricultural Soils

In 2020, agricultural soils emitted 260.0 kt NH₃ or 50.7 % of the total agricultural NH₃ emissions in Germany (512.3 kt NH₃). The main contributions to the total NH₃ emissions from agricultural soils are the application of manure (3.D.a.2.a), with 158.7 kt (61.0 %) and the application of inorganic N-fertilizers (3.D.a.1) with 50.1 kt (19.3 %).

Application of sewage sludge (3.D.a.2.b) contributes 0.7 % or 1.9 kt NH₃.

The application of residues from the digestion of energy crops (3.D.a.2.c) leads to 37.0 kt NH₃ or 14.2 %. N excretions on pastures (3.D.a.3) have a share of 12.3 kt NH₃ or 4.7 %.

In 2020, agricultural soils were the source of 98.6 % (107.2 kt) of the total of NO_x emissions in the agricultural category (108.7 kt). The NO_x emissions from agricultural soils are primarily due to application of inorganic fertilizer (3.D.a.1) (50.1 %) and manure (3.D.a.2.a) (34.3 %). Application of residues from digested energy crops (3.D.a.2.c) contributes 10.8 % to agricultural soil emissions, 4.3 % are due to excretions on pastures (3.D.a.3). Emissions from application of sewage sludge (3.D.a.2.b) contribute 0.5 %.

In 2020, the category of agricultural soils contributed 9.2 kt NMVOC or 3.1 % to the total agricultural NMVOC emissions in Germany. The only emission source was cultivated crops (3.D.e).

In 2020, agricultural soils contributed, respectively, 28.7 % (17.3 kt), 57.2 % (17.3 kt) and 15.1 % (0.7 kt) to the total agricultural TSP, PM₁₀ and PM_2.5 emissions (60.3 kt, 30.2 kt, 4.4 kt, respectively). The emissions are reported in category 3.D.c (Farm-level agricultural operations including storage, handling and transport of agricultural products).

The calculation of NH₃ and NOx (NO) emissions from the application of inorganic fertilizers is described in Vos et al. (2022), Chapter 11.1 ¹⁾.

German statistics report the amounts of fertilizers sold which are assumed to equal the amounts that are applied. Since the 2021 submission, storage effects are approximated by applying a moving average to the sales data (moving centered three-year average, for the last year a weighted two-year average, which assigns 2/3 of the weight to the last year).

Table 1: AD for the estimation of NH₃ and NOx emissions from application of inorganic fertilizers

NH₃ emissions from the application of inorganic fertilizers are calculated using the Tier 2 approach according to EMEP (2019)-3D-14ff ²⁾, distinguishing between various fertilizer types, see Table 2. For NO_x, the Tier 1 approach described in EMEP (2019) [10]-3D-11 is applied.

The emission factors for NH₃ depend on fertilizer type, see EMEP (2019)-3D-15. Table 2 lists the EMEP emission factors for the fertilizers used in the inventory. In order to reflect average German conditions the emission factors for cool climate and a pH value lower than 7 was chosen. For urea fertilizer the German fertilizer ordinance prescribes the use of urease inhibitors or the immediate incorporation into the soil from 2020 onwards. The NH3 emission factor for urea fertilizers is therefore reduced by 70% from 2020 onwards, according to Bittman et al. (2014, Table 15)³⁾.

Table 2: NH₃-EF for inorganic fertilizers

For NO_x, the simpler methodology by EMEP (2019)-3D-11 was used. The emission factor 0.040 from EMEP, 2019-3D, Table 3.1 has the units of kg N₂O per kg fertilizer N and was derived from Stehfest and Bouwman (2006)⁴⁾. The German inventory uses the emission factor 0.012 kg NO-N per kg N derived from Stehfest and Bouwman (2006). This is equivalent to an emission factor of 0.03943 kg NO_x per kg fertilizer N (obtained by multiplying 0.012 kg NO-N per kg N with the molar weight ratio 46/14 for NO₂: NO). The inventory uses the unrounded emission factor.

Table 3: Emission factor for NO_x emissions from fertilizer application

In the last years (and up to 2019 in dramatic fashion) fertilizer sales have decreased. Emissions have fallen accordingly. This is even more pronounced for NH₃ than for NO_x, as total NH₃ from the application of mineral fertilizers is, until the year 2019, very strongly correlated with the amount of urea applied (R2 = 0.89), the sales of which have decreased more than for all other mineral fertilizers. Since 2020 the negative trend is reinforced as urea fertilizer have to be either used with urease inhibitors or have to be incorporated into the soil directly, which causes 70% lower emissions (Bittman et al. 2014).

Table REC-1 shows the effects of recalculations on NH₃ and NO_x emissions. The only differences are in 2019 as the year 2020 is now included in the weighted average.

Table REC-1: Comparison of NH₃ and NO_x emissions from fertilizer application of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

In this sub category Germany reports the NH₃ and NO_x (NO) emissions from application of manure (including application of anaerobically digested manure). For an overview see Vos et al. (2022), Chapter 11.2.

The calculation of the amount of N in manure applied is based on the N mass flow approach (see 3.B). It is the total of N excreted by animals in the housing and the N imported with bedding material minus N losses by emissions of N species from housing and storage. Hence, the amount of total N includes the N contained in anaerobically digested manures to be applied to the field.

The frequencies of application techniques and incorporation times as well as the underlying data sources are described in Vos et al. (2022), Chapter 3.4.3. The frequencies are provided e. g. in the NIR 2022⁵⁾, Chapter 19.3.2.

Table 4: AD for the estimation of NH₃ and NO_x emissions from application of manure

NH₃ emissions from manure application are calculated separately for each animal species in the mass flow approach by multiplying the respective TAN amount with NH₃ emission factors for the various manure application techniques. For details see [3-b-manure-management 3.B] and Vos et al. (2022), Chapter 4 to 8 and 11.3. For NO_x emissions from manure application the inventory calculates NO-N emissions (see Vos et al. (2022), Chapter 11.2, that are subsequently converted into NO_x emissions by multiplying with the molar weight ratio 46/14. The Tier 1 approach for the application of inorganic fertilizer as described in EMEP (2019)-3D-11 is used, as no specific methodology is available for manure application.

Table 5 shows the time series of the overall German NH₃ IEF defined as the ratio of total NH₃-N emission from manure application to the total amount of N spread with manure.

Table 5: IEF for NH₃–N from application of manure

For NO_x the same emission factor as for the application of inorganic fertilizer was used (see Table 3).

Both NH₃ and NO_x emissions from the application of animal manures are key sources. Total NO_x is calculated proportionally to the total N in the manures applied which decreased remarkably from 1990 to 1991 due to the decline in animal numbers following the German reunification (reduction of livestock numbers in Eastern Germany). In the 1990s and 2000s this was followed by a weakened decline in animal manure amounts. From 2010 to 2014 there was a slight increase and since then the amount of N in manure applied has been slightly declining again, see Table 4. The NO_x emissions follow these trends. For total NH₃ emissions there is a slight negative trend. This is due to the increasing use of application practices with lower NH₃ emission factors.

Table REC-2 shows the effects of recalculations on NH₃ and NO_x.The total emissions of NH₃ and NO_x from application of manure are slightly lower than those of last year’s submission from the year 2000 onwards for NH₃, from the year 2010 onwards for NO_x. In earlier years the emissions are slightly higher than in last year’s submission.

These differences are predominantly caused by the update of data from the official agricultural census 2020 as well as the update of the suckler-cow model and the new raw protein contents in feed of fattening pigs and broilers, see main page of the agricultural sector, list of recalculation reasons, No. 1, 4, 7 and 8.

Much smaller is the impact of the updates of activity data for male cattle > 2 years, pigs, poultry and sheep (see recalculation reasons 5, 6 and 9 through 12) Further details on recalculations are described in Vos et al. (2022), Chapter 3.5.2.

Table REC-2: Comparison of the NH₃ and NO_x emissions of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

The calculation of NH₃ and NO_x (NO) emissions from application of sewage sludge is described in Vos et al. (2022), Chapter 11.4.

N quantities from application of sewage sludge were calculated from data of the German Environment Agency and (since 2009) from data of the Federal Statistical Office (see Table 6).

Table 6: AD for the estimation of NH₃ and NO_x emissions from application of sewage sludge

A tier 1 methodology is used (EMEP, 2019, 3D, Chapter 3.3.1). NH₃ and NO_x emissions are calculated by multiplying the amounts of N in sewage sludge applied with the respective emission factors.

EMEP (2019)-3.D, Table 3-1 provides a Tier 1 emission factor for NH₃ (0.13 kg NH3 per kg N applied) emissions from application of sewage sludge. The German inventory uses the equivalent emission factor in NH₃-N units which is 0.11 kg NH₃-N per kg N applied (cf. the derivation of the emission factor described in the appendix of EMEP (2019)-3D, page 26-27). For NO_x the same emission factor like for the application of inorganic fertilizer was used (see Table 3).

NH₃ and NO_x emissions from the application of sewage sludge are no key sources.

Table REC-3 shows the effects of recalculations on NH₃ and NO_x emissions. The only change compared to last year’s submission occurs for the year 2018 and 2019 due to the update of the activity data (see main page of the agricultural sector, recalculation No 15. Further details on recalculations are described in Vos et al. (2022), Chapter 3.5.2.

Table REC-3: Comparison of the NH₃ and NO_x emissions of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

This sub category describes Germany’s NH₃ and NO_x (NO) emissions from application of residues from digested energy crops. For details see Vos et al. (2022), Chapters 10.2 and 11.3.

Activity data is the amount of N in residues from anaerobic digestion of energy crops when leaving storage. This amount of N is the N contained in the energy crops when being fed into the digestion process minus the N losses by emissions of N species from the storage of the residues (see 3.I). N losses from pre-storage are negligible and there are no N losses from fermenter (see Vos et al. (2022), Chapter 10.2.1).

Table 7: AD for the estimation of NH₃ and NO_x emissions from application of residues from anaerobic digestion of energy crops

The NH₃ emissions are calculated the same way as the NH₃ emissions from application of animal manure (3.D.a.2.a). The frequencies of application techniques and incorporation times as well as the underlying data sources are provided e. g. in the NIR 2022, Chapter 19.3.2. The amounts of TAN in the residues applied are obtained from the calculations of emissions from the storage of the digested energy crops (3.I).

For NO_x emissions from application of residues the Tier 1 approach for the application of inorganic fertilizer as described in EMEP (2019)-3D-11 is used. The inventory calculates NO emissions that are subsequently converted into NO_x emissions by multiplying with the molar weight ratio 46/30.

For NH₃ the emission factors for untreated cattle slurry were adopted, see Vos et al. (2022), Chapter 10.2. As the NO_x method for fertilizer application is used for the calculation of NO_x emissions from the application of residues, the emission factor for fertilizer application was used (see Vos et al. (2022), Chapter 11.1)

Table 8 shows the implied emission factors for NH₃ emissions from application of residues from digested energy crops.

Table 8: IEF for NH₃-N

The application of residues from anaerobic digestion of energy crops is a key source for NH₃. Emissions are dominated by the amounts of N in the substrates fed into the digestion process and to a lesser extent by the increased use of application techniques with lower emission factors. They have become important since about 2005 and have risen sharply until 2013. Since then, they have changed little each year and tend to decrease slightly in the last few years. The latter is mostly due to a small negative trend of the amounts of energy crops digested.

Table REC-4 shows the effects of recalculations on NH₃ and NO_x emissions. The only changes compared to last year’s submission occur for the years 2015-2019, due to the use of new data on manure spreading techniques from the official agricultural census 2020 (see main page of the agricultural sector, list of recalculation reasons, No 1 and 16, and Vos et al. (2022), Chapter 3.5.2.)

Table REC-4: Comparison of the NH₃ and NO_x emissions of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

The calculation of NH₃ and NO_x (NO) emissions from N excretions on pasture is described in Vos et al. (2022), Chapter 11.5.

Activity data for NH₃ emissions during grazing is the amount of TAN excreted on pasture while for NO_x emissions it is the amount of N excreted on pasture.

Table 9 shows the N excretions on pasture. The TAN excretions are derived by multiplying the N excretions with the relative TAN contents provided in 3.B, Table 2.

Table 9: N excretions on pasture

NH₃ emissions from grazing are calculated by multiplying the respective animal population (3.B, Table 1) with corresponding N excretions and relative TAN contents (3.B, Table 2) and the fraction of N excreted on pasture (Table 9). The result is multiplied with the animal specific emission factor (Table 10). NO emissions are calculated the same way with the exception that the emission factor is related to N excreted instead of TAN.

The emission factors for NH₃ are taken from EMEP (2019)-3B-31, Table 3.9. They relate to the amount of TAN excreted on pasture. Following the intention of EMEP, 2019-3D, Table 3.1, the inventory uses for NO_x the same emission factor as for the application of inorganic fertilizer (see Table 3). In order to obtain NO_x emissions (as NO₂) the NO-N emission factor of 0.12 kg NO-N per kg N excreted is multiplied by 46/14.

Table 10: Emission factors for emissions of NH₃ and NO from grazing

Emissions from urine and dung deposited by grazing animals are no key sources.

Table REC-5 shows the effects of recalculations on NH₃ and NOx emissions.

Because overall N excretions on pasture are lower than in last year’s submission for dairy cattle, but higher for other cattle (predominantly due to new cattle grazing data from the official agricultural census 2020 and the update of the suckler-cow models, see main page of the agricultural sector, list of recalculation reasons, No 1 and 2), NO_x emissions are lower than in last year’s submission. However, although NH₃ emissions could be expected to show the same pattern, they are slightly higher than in the last submission in 1990-2013 and slightly lower than in last year’s submission from 2014 onwards. This is due to a combination of two effects: The TAN content of the suckler cows’ N-excretions is higher in the new suckler-cow model, which leads to higher emissions over the whole time series. This is over-compensated by declining dairy cow grazing times from 2014 onwards, which leads to lower emissions (see list of recalculation reasons, No 1 and 2). Further details on recalculations are described in Vos et al. (2022), Chapter 3.5.2.

Table REC-5: Comparison of the NH₃ and NO_x emissions of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

In this category Germany reports TSP, PM₁₀ and PM_2.5 emissions from crop production according to EMEP (2019)-3D-11. For details see Vos et al. (2022), Chapter 11.14.

The activity data is the total area of arable and horticultural land. This data is provided by official statistics.

Table 11: AD for the estimation of TSP, PM₁₀ and PM_2.5 emissions from soils

As the Tier 2 methodology described in EMEP (2019)-3D-17 cannot be used due to lack of input data, the Tier 1 methodology described in EMEP(2019)-3D-11 is used.

Emission factors given in EMEP (2019)-3D-12 are used. The Guidebook does not indicate whether EFs have considered the condensable component (with or without).

Table 12: Emission factors for PM emissions from agricultural soils

TSP and PM₁₀ are key sources. Emissions depend only on the areas covered. These are relatively constant, with a very slight decrease over the past 10 years.

Table REC-6 shows the effects of recalculations on particulate matter emissions. There are minor changes with respect to last year’s submission in several years because of updates of cultivation areas (see main page of the agricultural sector, list of recalculation reasons, No 17). However, due to the data format in Table REC-6, these differences are not visible. Further details on recalculations are described in Vos et al. (2022), Chapter 3.5.2.

Table REC-6: Comparison of particle emissions (TSP, PM₁₀ & PM_2.5) of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

In this category Germany reports NMVOC emissions from crop production according to EMEP (2019)-3D-16. For details see Vos et al. (2022), Chapter 11.12.

The activity data is the total area of arable land and grassland. This data is provided by official statistics.

Table 13: AD for the estimation of NMVOC emissions from crop production

The Tier 2 methodology described in EMEP (2019)-3D-16ff is used.

The emission factors for wheat, rye, rape and grass (15°C) given in EMEP (2019)-3D-16, Table 3.3 were used. For all grassland areas the grass (15°C) EF is used, for all other crops except rye and rape the EF of wheat is used. Table 14 shows the implied emission factors for NMVOC emissions from crop production. The implied emission factor is defined as ratio of the total NMVOC emissions from cultivated crops to the total area given by activity data.

Table 14: IEF for NMVOC emissions from crop production

NMVOC emissions from crop production are no key sources.

Table REC-7 shows the effects of recalculations on NMVOC emissions. There are minor changes with respect to last year’s submission in seral years because of updates of yields (see main page of the agricultural sector, list of recalculation reasons, No 17). However, due to the data format in Table Table REC-6, these differences are not visible. Further details on recalculations are described in Vos et al. (2022), Chapter 3.5.2.

Table REC-7: Comparison of NMVOC emissions of the submissions (SUB) 2021 and 2022

No improvements are planned at present.

Details are described in chapter 1.7.