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Reference metadata describe statistical concepts and methodologies used for the collection and generation of data. They provide information on data quality and, since they are strongly content-oriented, assist users in interpreting the data. Reference metadata, unlike structural metadata, can be decoupled from the data.

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Gross nutrient balance (aei_pr_gnb)

Reference Metadata in Euro SDMX Metadata Structure (ESMS)

Compiling agency: Eurostat, the statistical office of the European Union

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The Gross Nutrient Balance (GNB) provides an insight into the links between the use of agricultural nutrients, their losses to the environment, and the sustainable use of soil nutrients resources. It consists of the Gross Nitrogen Balance and the Gross Phosphorus Balance and is an indicator of the potential threat of surplus or deficit of two important soil and plant nutrients in agricultural land. It shows the link between agricultural activities and the environmental impact, identifying the factors determining the nutrients surplus or deficit and the trends over time.

Nitrogen (N) and Phosphorus (P) are key elements for plants to grow. A persistent deficit of these nutrients can in the long-term lead to soil degradation and erosion. When persistently applied in excess, they can lead to surface and groundwater (including drinking water) pollution and eutrophication.

The GNB also includes nitrogenous emissions from livestock production and the application of manure and fertilisers. These nitrogenous emissions include:

  • Ammonia (NH3) contributing to acidification, eutrophication, and atmospheric particulate pollution, and
  • Nitrous oxide (N2O), a potent greenhouse gas contributing to global warming.

The GNB is calculated as the balance between inputs and outputs of nutrients to the agricultural soil:

The inputs are:

  • Consumption of fertilisers,
  • Gross input of manure, and
  • Other inputs

The outputs are:

  • Removal of nutrients with the harvest of crops,
  • Removal of nutrients through the harvest and grazing of fodder, and
  • Crop residues removed from the field.

A net nitrogen balance is further calculated subtracting the nitrogenous emissions from the GNB. Balances per hectare of utilised agricultural area are also presented.

The total nutrient inputs and outputs to the balance are (except for mineral fertilisers) calculated by multiplying a factor with a coefficient that represents the impact in terms of nutrients (e.g., nutrient content in kg N or P per tonne, excretion coefficient in kg N or P/head).

The factors used include the consumption of inorganic and other organic fertilisers (excluding manure) (tonnes), livestock population (1000 heads), manure imports, exports, and withdrawals (tonnes), crop and fodder production (tonnes), crop residues removed from the field (tonnes) and the utilised agricultural area. Where available, these factors are directly retrieved from crop production and livestock statistics.

The coefficients are estimated by countries based on multiple methods, including measurements, scientific research, modelling, expert judgment, and default values.

5 March 2024

Reference AreaThe area (agricultural soils) to which the balance refers is the utilized agricultural area (UAA) as reported in the crop production statistics (apro_cpnh1).

Consumption of fertilisers: Total consumption of fertilisers is the sum of the consumption of inorganic fertilisers and other organic fertilisers (excluding manure). Inorganic fertilisers are manufactured fertilisers. Organic fertilisers include sewage sludge, urban compost, industrial waste products and other products which are used as fertilisers on agricultural soils.

Manure Input: Is the sum of manure production by livestock, added of manure imports and deducted from manure withdrawals and exports.

Other Inputs: Include the biological fixation of nitrogen by leguminous crops and grass-legume mixtures, the atmospheric deposition of nitrogen on agricultural soils and the seeds and planting materials planted in the soil.

Removal of nutrients with the harvest of crops: Include cereals, dried pulses, root crops, industrial crops, vegetables, fruit, ornamental plants and other harvested crops.

Removal of nutrients through harvest and grazing of fodder: Includes green fodder (for instance silage maize) and temporary and permanent Grasslands (hay, grass silage, fresh grass harvested and fed to animals, grass grazed by ruminants).

Removal of nutrients from crop residues removed from the field: Include straw, head leaves and stems and other crop residuals which are removed from the field.

Not applicable

EU Member States, Norway and Switzerland. The data refer to national level (NUTS level 0).

EU Member States, Norway and Switzerland. The data refer to national level (NUTS level 0).

Calendar year.

Accuracy and reliability of basic data used to construct the balance

 

Inorganic Fertilisers: Most countries use data based on sales and/or production and trade statistics. Some countries use farmer surveys. Data based on sales and/or production and trade statistics may be biased due to the inclusion of fertilisers not used in agriculture (private/public sector use, explosives, intermediate products etc). Reliability and accuracy of farmer surveys depend on the sampling design and size.

Organic Fertilisers (excluding manure): Data on organic fertilisers (excluding manure) are only available in some countries. Data from these countries show that organic fertilisers are not very significant in the N balance (<3% of total inputs on average between 2000-2014), the effect of missing data on organic fertilisers is therefore likely to be minor on the Gross Nitrogen Balance.

Manure production: Manure production is estimated from animal numbers and excretion coefficients. Animal numbers should reflect the average amount of animals present during the year. Data on cattle, pigs, goats and sheep are available from European statistics such as the annual livestock statistics, the FSS and livestock registers. Livestock surveys may not represent the average amount of animals well as they refer to a specific day, which means that offspring for instance may not be included very well, however a correction can be made in the excretion coefficients to take into account the offspring. For poultry and other livestock, data is less available. Some poultry types and equidea are counted in the FSS, countries may have other data sources available to estimate poultry and other livestock types. As manure is a large input in the balance, excretion coefficients have a big impact on the final outcome. Excretion coefficients vary widely between countries, partly this reflects differences in farming practices and partly differences are caused due to the applied methodology and availability of data to calculate the coefficients..

Manure withdrawals: Most countries do not have data or only limited data available on manure withdrawals. In the case where there are significant withdrawals, this may lead to some overestimation of the manure input.

Manure imports: Trade of manure occurs mainly from high surplus countries to neighbouring countries. The exact amounts which goes to which country are not known. The manure imports are likely to be less than 5% of the total N manure input.

Biological fixation: Biological fixation by leguminous crops is calculated based on the area of leguminous crops and fixation coefficients. Data on areas of leguminous crops are generally available from land use statistics. There is a wide variation in coefficients of biological fixation by leguminous crops between countries, partly this reflects differences in climate and partly differences are caused due to the applied methodology (measurements, scientific research, expert judgements).

Atmospheric N deposition: Atmospheric N deposition is estimated from land use data and deposition rates. Some countries annually update deposition rates. Countries use different methodologies to estimate deposition rates (models, measurements, expert judgment, scientific research). Data on national N deposition should be available for all signatories to the UNECE Convention on Long-Range Transboundary Air pollution. Modelled data is also available from EMEP.

Seeds and Planting materials: Data available show that share of seeds and planting material in total N input is <2%. It is also of minor importance for the P balance (<5% of total P input).

Harvested Crop production: Data on harvested crops are available from European statistics, the annual crop production statistics. Coefficients of nutrient contents of crop production vary between countries, partly this reflects differences in farming practices and climate and partly differences are caused due to the applied methodology (measurements, scientific research, expert judgements). It is necessary to review the coefficients used in relation to fertiliser and manure input and climate.

Crop residues: Available data shows that the share of crop residuals in total N and also P output is lower than 3.5% (average 2000-2014). The effect of missing data on crop residues is therefore likely to be minor on the Gross Nutrient Balance.

Fodder: The estimates of grassland production and consumption have a big impact on the balance outcome. At the moment, approaches to estimate grassland production and consumption vary significantly between countries and the uncertainty in the estimates is significant. Grassland production includes fresh matter, grass silage, hay and grass grazed by ruminants. The yield and nutrient content of grassland can be estimated from measurements, scientific research, and expert judgements. Grassland consumption can also be estimated from a fodder balance, based on feed requirements and statistics on other feed. The estimation of grass grazed is particularly difficult. Data are in many countries only partially available (in respect with grassland areas and products taken into account). There is a need to improve the estimation of grassland production and consumption.

Reference Area: Data on utilised agricultural area is available from Eurostat Crop Statistics.

Variables are measured in tonnes of nutrients. Except for the balance per ha, the inputs per ha and the outputs per ha which are expressed in kg of nutrient per hectare.

Data is compiled to produce EU aggregates whenever data for all countries is available.

The GNB is calculated as the balance between inputs and outputs of nutrients to the agricultural soil:

The inputs are:

  • Consumption of fertilisers,
  • Gross input of manure, and
  • Other inputs

The outputs are:

  • Removal of nutrients with the harvest of crops,
  • Removal of nutrients through the harvest and grazing of fodder, and
  • Crop residues removed from the field

The total nutrient inputs and outputs to the balance are (with the exception of mineral fertilisers) calculated by multiplying a factor with a coefficient that represents the impact in terms of nutrients (e.g. nutrient content in kg N or P per ton, excretion coefficient in kg N or P/head).

The factors used include the consumption of inorganic and other organic fertilisers (excluding manure) (tonnes), livestock population (1000 heads), manure imports, exports and withdrawals (tonnes), crop and fodder production (tonnes), crop residues removed from the field (tonnes) and the utilised agricultural area. Where available, these factors are directly retrieved from crop production in national humidity (apro_cpnh1) and livestock statistics (apro_mt_ls).

The coefficients are estimated by countries based on multiple methods, including: measurements, scientific research, modelling, expert judgment and default values.

The Eurobase table is updated as soon as national data is transmitted and validated by Eurostat.

The transmission deadline is laid down by the ESS agreement of 16 November 2017 on gross nutrient budgets which establishes that data is collected each 2 years and the deadline for data transmission is the 30th June of year T+2 (for data covering the time-series annually up to year T). Countries can also voluntarily provide data more frequently (i.e. annually).

Geographical comparability is currently limited due to the different methodologies applied to calculate coefficients and differences in data sources used. Therefore, data should not be directly compared between countries.

In general, there is a good comparability over time.