Indicator Assessment

Gross nutrient balance

Indicator Assessment

Prod-ID: IND-33-en

Also known as: CSI 025

Published 14 Nov 2005 Last modified 11 May 2021

8 min read

Topics: Water and marine environment

This page was archived on 09 May 2015 with reason: No more updates will be done

At EU-15 level the gross nitrogen balance in 2000 was calculated to be 55 kg/ha, which is 16% lower than the balance estimate in 1990, which was 66 kg/ha. In 2000 the gross nitrogen balance ranged from 37 kg/ha (Italy) to 226 kg/ha (the Netherlands). All national gross nitrogen balances show a decline in estimates of the gross nitrogen balance (kg/ha) between 1990 and 2000, apart from Ireland (22% increase) and Spain (47% increase). The following Member States showed organic fertiliser application rates greater than the threshold of 170 kg/ha specified by the Nitrates Directive in 2000: the Netherlands (206 kg/ha) and Belgium (204 kg/ha). The general decline in nitrogen balance surpluses is due to a small decrease in nitrogen input rates (-1.0%) and a significant increase in nitrogen output rates (10%).

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Gross nutrient balance at national level

Note: EEA calculations on the basis of the following: Harvested crops and forage Crop area (Eurostat's ZPA1 data set or Farm Structure Survey); Livestock numbers (Eurostat's ZPA1 data set or Farm Structure Survey); Livestock excretion rates (OECD or averaged coefficients from Member States); Fertiliser rates (EFMA); Nitrogen fixation (OECD or averaged coefficients from Member States Farm Structure Survey); Atmospheric Deposition (EMEP); Yields (Eurostat's ZPA1 data set or average coefficients from Member States).

Data source:

OECD website (http://webdomino1.oecd.org/comnet/agr/aeiquest.nsf) and EEA calculations

Downloads and more info

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 approximation of agricultural pressures on water quality. High nutrient balances exert pressures on the environment in terms of an increased risk of leaching of nitrates to groundwater. The application of mineral and organic fertilisers can also lead to emissions to the atmosphere in the form of nitrous dioxide and ammonia, respectively.
Gross nitrogen balances are above 100 kg N per ha and year in the Netherlands, Belgium, Luxembourg and Germany. They are particularly low in most Mediterranean countries given the overall lower livestock production in this part of Europe. It is currently not possible to provide gross nitrogen balance estimates for the new EU Member States and the accession as the relevant statistical data are under elaboration.
National balances, however, can mask important regional differences in the gross nutrient balance that determine actual nitrogen leaching risk at regional or local level. Individual Member States can thus have acceptable gross nitrogen balances at national level but still experience significant nitrogen leaching in certain regions, for example in areas with high livestock concentrations. There are a number of regions where pig livestock units have increased by more than 25% between 1990 and 2000 (for example, north-western Denmark, north-western France, north-eastern Spain and northern Belgium). These are likely to be regional 'hotspots' for high gross nitrogen balances that can lead to environmental pressures. Member States with high nitrogen balances are making efforts to reduce these pressures on the environment. These build on a range of different policy instruments, requiring considerable political effort to succeed given the significant social and economic consequences of reducing livestock production in many affected areas (van Grinsveen et al., 2004 and Mikkelsen et al., 2004).

Supporting information

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)

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

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

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

Inorganic fertilisers

o Simple mineral fertilisers

o Complex mineral fertilisers

o Mineral-organic compounds

Organic fertilisers (organic inputs from non agricultural sources)

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.

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.