Agriculture: nitrogen balance

Assessment versions

Published (reviewed and quality assured)

• No published assessments

Rationale

Justification for indicator selection

This indicator boasts several main advantages.

• Policy relevance: indicates the degree of nutrient pressure from agriculture on biodiversity and provides a proxy measure for the intensity of agriculture in general.
• Well developed and established.
• Broadly accepted and understood.
• Data routinely collected and updates can be done on an annual basis.

Scientific references

• No rationale references available

Indicator definition

The indicator estimates the potential surplus (or deficit) of nitrogen in agricultural land. It calculates the balance between nitrogen added to an agricultural system and nitrogen removed from the system annually in kilograms of nitrogen per hectare of utilised agricultural area. The input side of the balance counts mineral fertiliser application and manure excretion as well as atmospheric deposition, biological fixation and biosolids (compost, sludge and sewage) input. The output side of the balance represents the removal from grassland (grazing and mowing) and the net crop uptake (removal) from arable land. The gross nitrogen balance takes an 'extended soil' surface (or 'land' surface) as the system boundary, meaning that it also includes nitrogen losses from animal housing and manure management (e.g. storage) systems.  

The data used are partly based on expert estimates of various physical parameters for the individual countries as a whole. There may also be large regional variations within a country so national figures should be interpreted with care. 

To assess the trend in the development of the nitrogen balance, it is necessary to draw on average values over several years, as factors such as extreme weather conditions may influence the annual nitrogen surplus. In this case, 2000-2003, and 2011-2014 were taken as reference periods.

Units

The units used in this indicator are kilograms per hectare of utilised agricultural area.

Policy context and targets

Context description

High nitrogen inputs and losses generally coincide with high phosphorous and pesticide inputs and losses. The nitrogen balance is related to nutrient leaching risks: high nitrogen inputs and imbalances normally lead to high pressure on biodiversity within and outside the farmed environment.

Agriculture is intensifying in many places, causing increasing pressure on biodiversity. Increasing nitrogen availability favours a few nitrophilous species and suppresses many other, rarer species. The 'nitrogen balance' includes nitrogen input (fertilising, nitrogen fixation and nitrogen deposition among other things) and nitrogen output (denitrification and the emission of ammonia among other things) and thus reflects a major part of the nitrogen cycle and the impact of farm management on the hydrosphere and atmosphere. Nitrogen input (fertilising and nitrogen fixation) more directly affects the level of biodiversity in fields and grasslands.

Relation of the indicator to the focal area

The sustainable management of agricultural ecosystems would minimise the negative effects from excess nitrogen through management of the nitrogen-balance.

Targets

2020 EU Biodiversity Targets - target 3a: By 2020, maximise areas under agriculture across grasslands, arable land and permanent crops that are covered by biodiversity-related measures under the CAP so as to ensure the conservation of biodiversity and to bring about a measurable improvement in the conservation status of species and habitats that depend on or are affected by agriculture and in the provision of ecosystem services as compared tothe EU2010 Baseline, thus contributing to enhance sustainable management.

Related policy documents

• EU 2020 Biodiversity Strategy
  in the Communication: Our life insurance, our natural capital: an EU biodiversity strategy to 2020 (COM(2011) 244) the European Commission has adopted a new strategy to halt the loss of biodiversity and ecosystem services in the EU by 2020. There are six main targets, and 20 actions to help Europe reach its goal. The six targets cover: - Full implementation of EU nature legislation to protect biodiversity - Better protection for ecosystems, and more use of green infrastructure - More sustainable agriculture and forestry - Better management of fish stocks - Tighter controls on invasive alien species - A bigger EU contribution to averting global biodiversity loss

Methodology

Methodology for indicator calculation

The methodology for calculating the nitrogen balances is described in the Eurostat/OECD Nutrient Budgets Handbook .

The inputs to the nitrogen balance are:

• Fertilisers, which consist of:
•         inorganic fertilisers,
•         organic fertilisers (excluding manure).
• Gross manure input, which is calculated from:
•         manure production (nitrogen excretion; according to the current methodology no reductions are made for nitrogen losses due to volatilisation in stables, storage and application to the land);
•         manure withdrawals (manure export, manure processed as industrial waste, non-agricultural use of manure, other withdrawals);
•         change in manure stocks;
•         manure import.
• Other nitrogen inputs, which consist of:
•         seeds and planting material;
•         biological nitrogen fixation by leguminous crops and grass-legume mixtures;
•         atmospheric deposition.

The outputs of the gross nitrogen balance are: 

• Total removal of nitrogen with the harvest of crops (cereals, dried pulses, root crops, industrial crops, vegetables, fruit, ornamental plants, other harvested crops);
• Total removal of nitrogen with the harvest and grazing of fodder (permanent grassland and fodder from arable land including temporary grassland);
• Crop residues removed from the field.

Methodology for gap filling

No gap filling was used for this indicator.

Methodology references

No methodology references available.

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• Gross nitrogen balance

Data sources in latest figures

Uncertainties

Methodology uncertainty

No uncertainty has been specified.

Data sets uncertainty

No uncertainty has been specified.

Rationale uncertainty

This indicator has several main disadvantages:

• The data are available at national level. However, national nitrogen balances can hide great regional variation and thus lead to regional problems being overlooked. This is a particular issue for larger countries with different areas under different (intensive or extensive) agricultural regimes.
• Input and balance of nutrients is only one of the factors that determine agricultural intensity and are relevant to biodiversity. Pesticide use and crop diversity, for example, are also important.