Gross nutrient balance

Assessment versions

Published (reviewed and quality assured)

• No published assessments

Rationale

Justification for indicator selection

Nutrient or mineral balances provide insight into links between agricultural nutrient use, changes in environmental quality, and the sustainable use of soil nutrient resources. A persistent surplus indicates potential environmental problems; a persistent deficit indicates potential agricultural sustainability problems. With respect to environmental impacts, however, the main determinant is the absolute size of the nutrient surplus/deficit linked to local farm nutrient management practices and agro-ecological conditions, such as soil type and weather patterns (rainfall, vegetation period etc.).

The gross nutrient balance for nitrogen provides an indication of potential water pollution and identifies those agricultural areas and systems with very high nitrogen loadings. As the indicator integrates the most important agricultural parameters with regard to potential nitrogen surplus it is currently the best available measure for nutrient leaching risk.

Scientific references

• No rationale references available

Indicator definition

The indicator estimates the potential surplus of nitrogen on agricultural land. This is done by calculating the balance between nitrogen added to an agricultural system and nitrogen removed from the system per hectare of agricultural land.

The indicator accounts for all inputs to and outputs from the farm. The inputs consists of the amount of nitrogen applied via mineral fertilisers and animal manure as well as nitrogen fixation by legumes, deposition from the air, and some other minor sources. Nitrogen output is contained in the harvested crops, or grass and crops eaten by livestock (escape of nitrogen to the atmosphere, e.g. as N₂O, is difficult to estimate and therefore not taken into account).

Units

Kilogram per year (kg/year) per hectare (ha)

Policy context and targets

Context description

The gross nitrogen balance is relevant to two EU Directives: the Nitrates Directive (91/676/EC) and the Water Framework Directive (2000/60/EC). The Nitrates Directive (Council of the European Communities, 1991) has the general purpose of "reducing water pollution caused or induced by nitrates from agricultural sources and prevent further such pollution" (Art.1). A threshold nitrate concentration of 50 mg/l is set as the maximum permissible level, and the Directive limits applications of livestock manure to land to 170 kg N/ha/yr. The Water Framework Directive (Council of the European Communities, 2000) requires all inland and coastal waters to reach "good status" by 2015. Good ecological status is defined in terms of the quality of the biological community, hydrological characteristics and chemical characteristics. The Sixth environmental action programme (European Commission, 2001), encourages the full implementation of both the Nitrates and Water Framework Directives, in order to achieve levels of water quality that do not give rise to unacceptable impacts on, and risks to, human health and the environment.

Targets

No specific targets

Related policy documents

• Council Directive (91/676/EEC) 12 December 1991
  Council Directive of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources (91/676/EEC).
• Directive 2001/81/EC, national emission ceilings
  Directive 2001/81/EC, on nation al emissions ceilings (NECD) for certain atmospheric pollutants. Emission reduction targets for the new EU10 Member States have been specified in the Treaty of Accession to the European Union 2003  [The Treaty of Accession 2003 of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia. AA2003/ACT/Annex II/en 2072] in order that they can comply with the NECD.
• Water Framework Directive (WFD) 2000/60/EC
  Water Framework Directive (WFD) 2000/60/EC: Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy.

Methodology

Methodology for indicator calculation

The classification system used is derived from the OECD/Eurostat national nutrient balances, which has hierarchical coding for the following categories of inputs and outputs.

Total nitrogen inputs to farm unit

F1 Total Fertilisers

o Simple mineral fertilisers

o Complex mineral fertilisers

o Mineral-organic compounds

o Urban compost

o Sewage sludge spread on agricultural land)

A1 Livestock manure production

M2x Manure stocks (stock levels, imports and exports of livestock manure)

B1. Biological nitrogen fixation (nitrogen fixed in the soil)

L111. Atmospheric deposition of nitrogen compounds

C1. Other inputs (seeds and planting material, ...)

Total nitrogen outputs from farm unit

C2 Total harvested crops and forage

a. Marketed crops, including marketed fodder crops

b. Non-marketed fodder crops and grass (harvested and grazed)

Note: Subtracting the sum of the total nitrogen output under C2 from the total nitrogen input as listed in categories F1 to C1 results in the gross nutrient balance for nitrogen.

Methodology for gap filling

No information provided

Methodology references

No methodology references available.

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• Agriculture and Environment statistics (Eurostat)

Data sources in latest figures

Uncertainties

Methodology uncertainty

The data used for calculating gross nutrient balance are partly based on experts' estimates of different physical relations for the country as a whole. However in reality, there may be large regional variations for some of these, and therefore the regional figures should be interpreted with care. Before comparing Member States, it should also be borne in mind that the calculations are based on a harmonised methodology, which may not in all cases reflect country-specific particularities. Moreover, the N-coefficients supplied by Member States also differ remarkably between countries, to an extent which is sometimes difficult to explain.

As a general rule, the data on inputs are estimated to be more accurate and reliable than the data on outputs. Not only are the calculations on outputs mainly based on statistics at national level extrapolated to regional level, but also lack of (reliable) data on harvested fodder and grass adds an element of uncertainty to the figures. As this uncertainty is carried through to the total N-balance, the same precautions should also be taken before drawing conclusions from the results of the total balance. Nevertheless, the indicator is a good tool for identifying agricultural areas at risk of nutrient leaching.

Data sets uncertainty

Areas where data sets are not sufficiently developed include statistics on organic fertilisers, areas under cultivation by secondary crops, statistics for seeds and other planting material, and statistics for non-marketed production and residues.

Rationale uncertainty

No uncertainty has been specified

Work description

Resource needs

No resource needs have been specified

Status

Deadline