2.3. Farm’s Level Data—The Key Issue—FADN Significance
Data from the Polish FADN database were used to assess greenhouse gas emissions at the farm level. FADN is the European system for collecting accounting data from agricultural holdings. On average, FADN data in Poland are collected from approximately 11,000 farms.
The specificity of FADN means that not all data necessary for full emission determination are available. Basic data such as the size of the livestock, the sown area or the size of the harvest, as well as information on the amount and type of mineral fertilisation, are available; however, data on fertilisation with natural fertilisers or agricultural practices are not collected. Natural fertilisation can be estimated based on the size of the livestock population, which was used in this study. Estimations concerned with energy use in quantitative terms. Energy consumption was estimated based on cost data available in FADN sources. As a result, it is necessary to use indirect methods to obtain other relevant data and estimate emissions on this basis. Nevertheless, FADN data seem to be the most suitable for this purpose, due to the unified system of data collection in individual EU Member States, their annual collection, and their representativeness for the population of commercial farms in a given country, taking into account the size and type of agricultural farms.
In the FADN database, there are commercial farms with a Standard Output of at least 4000 euros. This means that most farms in Poland are not represented in this database, due to their small-scale production; thus, the FADN data are not representative of the entire sector. This also makes it impossible to compare them with the emission data estimated and published by KOBiZE, which applies to the entire agricultural sector. Nevertheless, commodity farming, due to its large-scale production, has a significant impact on the volume of emissions from the agricultural sector.
The study utilised individual data from the 2023 FADN database. This is the latest data at the time of the research. The division of farms into types in accordance with the Community Typology of Agricultural Holdings was applied.
In this way, eight groups of farms (TF8) are distinguished, i.e.,
Fieldcrops;
Horticulture;
Wine;
Other permanent crops;
Milk;
Other grazing livestock;
Granivores;
Mixed.
The study omits the third type of farms, i.e., Wine Farms, which are not included in the study as part of the Polish FADN due to the relatively small scale of production of this type in Poland. Types 1–7 indicate that the farm is specialised in a specific profile of agricultural activity, while Type 8 indicates multidirectional farms, which are non-specialised with mixed plant and animal production. If a farm obtains at least 2/3 of the standard output value from a specific type of agricultural activity, it is classified as one of the 1–7 types; otherwise, if the farm diversifies sources of standard output value, it is considered a mixed one (type 8).
2.4. GHG Calculation Stages—IPCC Basis vs. Assumptions and Estimations Adopted to FADN
Based on the IPCC methodology and the scope of the FADN data, emissions from the Agricultural sector were estimated for the study. Emissions from the energy sector were partially taken into account, while emissions from Sector 5, i.e., land change, were omitted. The lack of estimates results from the inability to calculate them based on the available data.
As a result, emissions were divided into the following sources, which were determined (calculated or estimated):
Emissions of livestock origin.
Direct emissions from soils.
Indirect emissions from soils.
Field burning of agricultural residues.
Emissions from fuel combustion.
Emissions from electricity consumption.
Ad. (1) Emissions of livestock origin
As part of the emissions from livestock origin, three variables were considered: CH
4 emissions from the enteric fermentation process and the emissions of two gases (CH
4 and N
2O) from manure management processes. The method used to calculate emissions is shown in
Table 3. The calculations used indicators for 2022, i.e., the latest ones published by the KOBiZE (2024). Their list is presented in
Table 4. It is worth noting that these indicators are the result of complex calculations carried out by KOBiZE and are subject to change in the future. For this reason, appropriate indicators should be used for each year included in the research. In the present case, due to the lack of publication of indicators for 2023, it was decided to use the most recent ones, e.g., for 2022.
Ad. (2) Direct emissions from soils
Estimating direct emissions from soils is the most complex area of analysis. As part of the analysis, these emissions were divided into two groups, i.e.,
- (a)
related to the use of mineral fertilisers and
- (b)
into other sources.
This division is a result of the needs of this research, not the IPCC methodology. Such a division was aimed at emphasising the role of mineral fertilisation in the emission of the farm. In the first group, there are three processes: emissions from nitrogen mineral fertilisers, from urea, and from liming. The method of their calculation is presented in
Table 5.
The emission factor means that 1 kg of nitrogen mineral fertiliser emits 0.01 kg of N2O-N. The fraction 44/28 is used for the conversion of kg N2O-N/kg N to kg N2O.
Based on FADN data, it is not possible to accurately calculate the amount of urea used. For this reason, an indirect method of calculating these emissions was adopted, based on the conversion of the amount of nitrogen fertilisers used by an appropriate factor, which in 2023 amounted to 24.2%. This figure is based on market data, which indicates the share of urea in sales of mineral nitrogen fertilisers. The Emission Index for Urea means that 1 t of urea emits 0.2 t of CO2-C.
In the case of liming, the Polish FADN database also does not contain direct quantitative data on lime fertilisers. For this reason, it is necessary to estimate this value indirectly by adopting an appropriate coefficient based on market data for the agricultural sector, which indicates the average price of CaO and the average share of CaO in lime fertilisers. However, these data change annually, requiring adequate calculations. The emission factor is 0.12, which means that 0.12 t of CO2-C is emitted from 1 t of CaO.
The fraction 11/3 refers to the conversion of kg CO2-C to kg CO2.
In the second group of other direct emission processes from soils, three processes were also taken into account, i.e.,
Table 6.
Method for calculating emissions from soils of natural origin (kg N2O).
Table 6.
Method for calculating emissions from soils of natural origin (kg N2O).
Process | Calculation Method |
---|
Organic N fertilisers use animal manure | =[(number of animals of a given species and by age × total amount of nitrogen in animal excreta (Nex) × fraction of total annual nitrogen excretion for each livestock category managed in manure management system (MS)) × (1 − the amount of manure nitrogen for the animal category of the species and age that is lost in the manure management system)] × (44/28) |
Urine and dung deposited by grazing animals | =[number of animals of a given species and by age × total amount of nitrogen in animal excreta (Nex) × fraction of total annual nitrogen excretion for each livestock category managed in manure management system (MS)] × (44/28) |
Crop residues | ={harvested annual dry matter yield for crop × [ratio of above-ground residues dry matter to harvested yield for crop (RAG(T)) × N content of above-ground residues for crop (NAG(T)) × (1 − fraction of crop residues burned (FracBurn(T)) − fraction of above-ground residues of crop T removed annually for purposes such as feed, bedding and construction (FracRemove(T)))] + ratio of below-ground residues to harvested yield for crop (RBG(T)) × content of below-ground residues for crop (NBG(T))} × 0.01 × (44/28) |
In this group, due to the lack of data, emissions from fertilisers of urban origin and emissions from histosols were omitted. The calculation of emissions belonging to this group should be classified as one of the most complex processes.
N2O emissions from the use of organic nitrogen fertilisers require a number of calculations and assumptions. The starting point is to calculate the amount of fertilisers that have been used on the farm in the pure component. Based on FADN data, it is possible to calculate the main source of organic fertilisers, namely, the amount of fertilisers from the farm. Fertilisers from sewage systems and natural fertilisers traded on the market from/to the farm were omitted due to the lack of relevant data. Given the negligible market for trade in natural fertilisers, these figures do not significantly affect the overall estimate.
Estimating the amount of manure available on a farm involves a series of complex calculations, as outlined in
Table 6. For this study, calculations were performed under conditions prevailing in Poland. Based on this, it is necessary to calculate the amount of nitrogen available for use in fertilisation. This requires calculating and subtracting from the total available organic nitrogen the part that remained in the form of faeces on pasture and was oxidised. Calculations should be made for the same species that were taken into account when calculating emissions of animal origin. Due to the lack of adequate information on the use of mulching, this element was not included in the FADN calculations. Emissions from this source should be added to the result obtained for each source.
The Nex(T) (
Table 7) and MS(T, S) indices (cf.
Table 8) vary by year and are published by KOBiZE.
The result of the estimation should be multiplied by the appropriate emission index, which is 0.001 for poultry and 0.005 for other animals considered in the FADN system.
To calculate emissions from urine and dung deposited by grazing animals, the number of animals of a given species and age is multiplied by the Nex indicator (
Table 7) and by the MS indicator presented in
Table 8. The sum of emissions for individual animals is the amount of emissions for the farm from manure left on pastures, ranges, and paddocks.
Emissions from crop residues left in the fields are calculated separately for each crop. The counting method is presented in
Table 6. The indicators necessary to calculate emissions are presented in
Table 9.
Additionally, it is necessary to calculate the R
AG(T) (Formula (1)) and R
BG(T) (Formula (2)). The method for calculating these indicators is presented in the IPCC guide [
58].
To calculate them, it is necessary to calculate the Above-ground residue dry matter (AG
DM(T)) index (Formula (3)).
Indicators necessary for the calculation of R
BG(T) and AG
DM(T) are presented in
Table 9.
Ad. (3) Indirect emissions from soils
Indirect emissions from soils are calculated based on two processes: atmospheric nitrogen volatilisation and nitrogen leaching and runoff. In both cases, the issue concerns N2O.
To calculate the amount of volatilised nitrogen, it is necessary to multiply the amount of mineral nitrogen in the pure component by 0.1. To this result, the sum of nitrogen from organic fertilisation, with the nitrogen left in the field, multiplied by 0.2, should be added. The number calculated in this way should be multiplied by the emission factor of 0.01. The result obtained should be multiplied by 44/28 and then by the GWP index.
In the case of leaching and runoff, the sum of all available nitrogen, i.e., nitrogen used for mineral and organic fertilisation and left by animals on pastures and in crop residues, should be multiplied by 0.3 and then by 0.0075. The value obtained in this way should be reduced to the appropriate unit, i.e., CO2 equivalent, by multiplying successively by 44/28 and by the GWP index.
The result of the sum of the above calculations is the amount of indirect emission.
Ad. (4) Emissions from the field burning of agricultural residues
Field burning of agricultural residues is a marginal practice, as it is prohibited by the GAEC 3 standard [
61]. However, due to historical experience and exceptional situations, e.g., fires, it is still included in national reports. Using FADN data, emissions from this source can be calculated using an indirect method, similar to calculations made by KOBiZE for the entire agricultural sector. As a result, this emission is calculated separately for each cultivated plant. To do this, one can multiply the harvest volume in tonnes by the corresponding proportion of the crop left in the fields. The result obtained should be multiplied by the emission factors for CH
4 and N
2O. The relevant indicators are presented in
Table 10.
The sum of the results obtained for all crops is the number of emissions from the combustion of crop residues.
Ad. (5 and 6) Emissions from fuels and electricity consumption
Emissions from energy use were also included in the study. Two sources of energy, i.e., fuel and electricity, were taken into account. In the Polish FADN, data on energy consumption is collected only in the form of the costs of its consumption. This applies to electricity and fuel. Therefore, these data were the starting point for determining the estimated amount of consumption in physical units.
In the case of fuels, it was assumed that the total energy consumption is for diesel oil. As a result, fuel costs were divided by the annual average diesel price in 2023 to calculate the amount of consumption. It amounted to 6.7 PLN/L (calculated based on data from official statistics). Emissions are calculated by multiplying the amount of fuel consumed by the corresponding emission factor for that fuel, which in transport is 2.64 kg CO2/L.
In the case of electricity, the cost of this energy from the FADN database was divided by the average price of electricity, which in 2023 was 0.7840 PLN/kWh [
62]. The result obtained was multiplied by 3.6 to convert units from kWh/kg to MJ/kg emission factor for the specified year. This indicator is published every year in the relevant regulation of the Minister of Climate and Environment. For 2023, this indicator is 182.1 gCO
2 eq/MJ [
63]. The result obtained should be divided by 1000 to obtain the emission in kilograms.