Archive:Agri-environmental indicator - risk of pollution by phosphorus

Data from August 2018

Planned update: April 2020

Highlights

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The gross phosphorous balance for the EU decreased from 3.9 kg per hectare per year in the period 2004-2006 to 1.2 kg per hectare per year in the period 2013-2015.

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The phosphorous surplus on EU agricultural land more than halved from 2004-2015.

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This article provides a fact sheet of the European Union (EU) agri-environmental indicator risk of pollution by phosphorus. It consists of an overview of recent data, complemented by all information on definitions, measurement methods and context needed to interpret them correctly. The risk of pollution by phosphorus article is part of a set of similar fact sheets providing a complete picture of the state of the agri-environmental indicators in the EU.

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Key messages

• Phosphorous is an important plant nutrient and the EU is almost entirely dependent on imports to fulfill the need of this agricultural fertiliser.
• The indicator gross phosphorous balance provides an indication of the surplus of phosphorous (P) on agricultural land (kg P per hectare per year). It also provides trends on phosphorous inputs and outputs on agricultural land over time.
• When calculated as 3-year averages to smooth out differences due to weather or input prices, the average gross phosphorus balance (GPB) per hectare of utilised agriculture area (UAA) in EU-28 decreased from 3.9 to 1.2 kg P per ha UAA (Figure 1) from 2004 to 2015. It means that the surplus is only around 30 % of what is was in the early 2000s and a significant decrease has been achieved.
• The GPB decreased in most countries between 2004 and 2015 (Table 1). Slight increases were seen only in Cyprus, Latvia, Hungary and Austria. It is worth noting that the GPB of Hungary remains negative, which indicates a risk for soil depletion.
• The quality and accuracy of the estimated gross phosphorus surplus per hectare depends on the quality and accuracy of underlying data and coefficients used. As methodologies (especially with regards to the coefficients) and data sources used in countries vary, the balances are only consistent within a country across time. The gross phosphorus balances are not consistent across countries, which mean that data cannot be compared between countries. Trends can be compared between countries.

• The gross phosphorus balance can only indicate the potential risk to the environment while the actual risk depends on many factors including climate conditions, soil type and soil characteristics, management practices such as drainage, tillage, irrigation etc. The risk of phosphorus pollution is only partially determined by the phosphorus balance of a particular year. It is often more strongly determined by the cumulative P balance of the past. Therefore it would be more accurate if results of the main indicator could be interpreted in relation to the subindicator "vulnerability to phosphorus leaching/run-off". However, this subindicator is still not developed.  

Analysis at EU level

The GPB for the EU-28 decreased from an estimated average of 3.9 kg P per ha per year in the period 2004-2006 to 1.2 kg P per ha per year in the period 2013-2015. The inputs of the gross phosphorus balance consist of mineral fertilisers, organic fertilisers and manure input, and other inputs like seeds and planting material. Mineral fertilisers and manure accounted for more than 93 % of the P input in EU-28 between 2010 and 2014 (country data are not complete for 2015, therefore 2014 values are used for this section). Other organic fertilisers such as compost, sewage sludge, industrial waste accounted for little more than 5 % of total P inputs. Data on other organic fertilisers are however lacking in many countries, therefore the significance of these fertilisers could be underestimated. Other inputs (e.g. seeds and planting material) represented only 1 % of total phosphorus input.

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Analysis at country level

As explained in the notes on the data and methodology used, the current balances are not comparable between countries due to differences in definitions, methodologies and data sources used. The average GPB per ha in 2013-2015 was highest in the Mediterranean islands Cyprus and Malta (Figure 2). The balance was negative for Bulgaria, Estonia, Slovakia, Czech Republic, Germany, Romania, Hungary and Italy (Figure 2). Increasing trends were very slight, and concerned Cyprus, Latvia, Hungary and Austria. However, as regards Hungary, the balance of phosphorous remains negative since the beginning of the data collection. This indicates a risk for negative effects on soil quality, since more phosphorous is removed from the soil than what is added.

There are large differences between countries in the use of inputs. Phosphorus is not available to the plant in the same rate for different types of manure and fertilisers. Manure input in the gross phosphorous balance is based on manure production, manure withdrawals and manure import where the manure production is calculated from livestock numbers and excretion factors. The agri-environmental indicator livestock patterns shows the livestock density in EU-28. Malta, the Netherlands, Belgium, Denmark, Cyprus and Ireland have the highest livestock densities and also have the highest rates of manure input per ha (over 14 kg P per ha per year). Bulgaria, Estonia, Latvia, Lithuania and Slovakia have the lowest livestock densities and also belong to the countries with the lowest rates of manure input per ha (less than 6 kg P per ha per year). The countries with the highest livestock densities also belong to the countries with a high share (over 60 %) of manure in total nutrient input.

Vulnerability to phosphorus leaching/run-off

The subindicator needs to be developed. Currently only limited data are available.  The vulnerability to P leaching, or P-sensitivity, refers to the combined risk of phosphorus loss to the groundwater or to the surface water by combinations of low sorption capacity, high erosion risk and increased risk of drainage. In 2005 the European Commission commissioned a study Addressing phosphorus related problems at farm practice from which Map 1 is derived. It shows the P-retention capacities of soils in Europe; the capacity of the soil to retain phosphorus by sorption and by resistance to erosion. Sorption of P in the soil is here defined as a process whereby readily soluble phosphate is changed to less soluble forms by reacting with inorganic or organic compound of the soil so that P becomes immobilized.

Red colour in Map 1 corresponds to class 1: very weak P retention capacities, dark green corresponds to class 5: very strong P retention capacities. As can be seen from this map, very dense clusters of soils with very low P retention capacities (class 1) can be found in Finland, Scotland, the north of England, the north of Ireland, Northern Ireland, the Netherlands, the north of Belgium and the Baltic states. Scattered clusters of class 1 soils can be found in the north of Germany, Poland and Greece. Also clusters of soils with low P retention capacities (class 2, orange colour) are detected. These clusters are found in the northwest of Spain and in the Alps. Phosphorus can easily be leached from highly organic soils (e.g. peat) and from sandy soils with low retention capacity. Small amounts are lost from most soils, but when the soils become phosphate saturated, leaching will be enhanced. P accumulation in soils might increase concentrations of dissolved and colloidal P in drainage. Calcareous soils on flat land were found to be the least sensitive to P surplus.

Areas at risk of encountering potential phosphorus excess were indicated in the study by estimating phosphorus balances and combining them with the proportion of vulnerable soils. The Netherlands and Slovenia display the highest rate of vulnerable soils and high balance surplus. In the Netherlands sensitive soils are prone to leaching, in Slovenia, erosion and run-off are the main agents of phosphorus loss.

Data sources and availability

Indicator definition

Potential surplus of phosphorus on agricultural land (kg P per ha per year).

Measurements

Main indicator:

• Potential surplus of phosphorus on agricultural land (kg P per ha per year).

Subindicator:

• Vulnerability to phosphorus leaching/run-off (to be developed).

Links with other indicators

• AEI 05 - Mineral fertiliser consumption
• AEI 10.1 - Cropping patterns
• AEI 10.2 - Livestock patterns
• AEI 11.1 - Soil cover
• AEI 11.2 - Tillage practices
• AEI 11.3 - Manure storage
• AEI 21 - Soil erosion

Data used and methodology

Main indicator: gross phosphorus balance

The methodology of the phosphorus balances is described in Eurostat/OECD Phosphorus Balance Handbook. The phosphorus balance lists all inputs and outputs into and out of the soil and calculates the gross phosphorus surplus as the difference between total inputs and total outputs. The gross phosphorus surplus per ha is derived by dividing the total gross phosphorus surplus by the reference area. The reference area of the current version of balances uploaded in Eurobase is the UAA.

The inputs of the phosphorus balance are:

• Fertilisers, which consist of:

• inorganic fertilisers,
• organic fertilisers (excluding manure).

• Gross manure input, which is calculated from:

• manure production (phosphorus excretion);
• manure withdrawals (manure export, manure processed as industrial waste, non-agricultural use of manure, other withdrawals);
• change in manure stocks;
• manure import.

• Other phosphorus inputs, which consist of :

• seeds and planting material;
• atmospheric deposition.

The outputs of the gross phosphorus balance are:

• Total removal of P with the harvest of crops (cereals, dried pulses, root crops, industrial crops, vegetables, fruit, ornamental plants, other harvested crops).

• Total removal of P with the harvest and grazing of fodder (fodder from arable land, permanent and temporary pasture consumption).

• Crop residuals removed from the field.

The P inputs and P outputs are estimated for each item of the balance from basic data multiplied with coefficients to convert the data in P content. Basic data (fertiliser consumption, crop production, livestock number, agricultural area) are mostly derived from statistics. Coefficients are mainly estimated by research institutes and can be based on models, statistical data, measured data as well as expert judgements.

Due to methodological issues or missing data, balances have been estimated by Eurostat for Belgium, Bulgaria, Denmark, Greece, Spain, Croatia, Italy, Cyprus, Latvia, Lithuania, Luxembourg, Malta, Austria, Romania and Slovakia.

Data on fertiliser consumption is available in many countries from country specific data sources (surveys, trade/production statistics). For countries where such data was not available, data from Fertilizers Europe have been used. Due to different data sources used (farmer surveys vs trade/production statistics) and inherent problems of data sources used (for instance inclusion of non-agricultural use in statistics based on trade and production) the quality of data cannot be sufficiently verified. There is need for a common methodology to estimate fertiliser consumption by agriculture to ensure reliable and consistent estimations and comparability across countries. 

Data on crop production, livestock number, and agricultural area are available in all countries from harmonised and regulated European statistics (FSS, animal production statistics, livestock registers, crop production statistics). Data on livestock numbers, crop production and reference area have been checked with Eurostat statistics. These data can be considered to be of good reliability.

Excretion coefficients delivered by the country have been used together with the livestock numbers reported by the country to estimate manure production. In the case where the country did not deliver excretion coefficients: the P excretion coefficients vary among countries due to differences in farming practices etc. If N coefficients were available for the country the average P:N relation of available countries has been multiplied with the N coefficient to estimate the P coefficient. Though the N:P ratio may vary between countries due to differences in farming practices it is assumed this variation is less than the variation in P excretion coefficients between countries. If N coefficients were not available P coefficients have been based on other country coefficients. Verification and validation of the coefficients requires expert knowledge. A European uniform methodology and validation procedure to estimate excretion coefficients would be necessary to ensure reliable and consistent estimations and comparability across countries. At present the estimation of coefficients varies between countries in methodology (expert judgement vs complex models based on statistical data) and in updating procedures (to take into account the effect of mitigation actions (other than reducing the level of production) in the estimations, coefficients need to be updated regularly to reflect these changes in farmer practices (mitigation actions)). Because manure input is a large part of the balance, caution should be taken when comparing the data (especially the level of surplus) between countries as these are largely depending on coefficients used which are based on varying methodologies.

Data on manure withdrawals, manure stocks and imports were not available in most countries. Available data on manure withdrawals for non-agricultural use show that this input is significant (more than 5 % of total manure input) in some countries (Belgium, the Czech Republic, the Netherlands), while non-significant in other countries (the United Kingdom, Switzerland).

Almost no country had data available on changes in manure stocks. Under normal circumstances it can be assumed that the change in manure stocks is on average zero.

Data on manure imports were only available from Switzerland, Austria and Belgium. Manure imports were insignificant (less than 1% of total manure input) for these countries. Trade of manure is mainly from high surplus countries to neighbouring countries. It is known that there are exports from for instance the Netherlands to Germany. It is likely that countries with a high nutrient surplus like Belgium and Denmark may export manure as well.

Data on crop production is available from reliable statistics for most of the significant crops cultivated except grassland. The harvest and grazing of grassland is estimated in some countries based on feed requirement models (for example in the Netherlands), while in other countries expert judgments are used. As grassland production (from temporary and permanent grassland) is estimated on average at 34 % of total P output in the EU-28 in 2010-2014, the estimation of grassland production determines to a large extent the outcome of the balance. It is necessary to develop a uniform European method to estimate grassland production to ensure reliable and consistent estimations and comparability across countries. For permanent crops a part of the P uptake is stored in the plant (which is not harvested) and is therefore not at risk to run-off, leaching or volatilisation. This is not taken into account in the balance estimations. Some countries do not have coefficients (used to convert the production in nutrient content) available and reliability varies due to the method used (scientific research vs expert judgments). Verification and validation of these coefficients requires expert knowledge. A sufficient European structure to verify and validate these coefficients is missing. Improvements of the methodologies to calculate more reliable coefficients used in countries are therefore of great importance.

Data on seeds and planting material were not available in all countries. The quality of available data depends on the data sources and assumptions made, as well as the quality of coefficients. Available data show this input is less than 2 % of total P input.

Atmospheric deposition of P is currently, according to the Nutrient Budgets handbook, not included in the practical implementation.

Reference area has a large impact on the final balance per hectare. After several discussions with countries and other stakeholders during the process of the last revision of the Nutrient Budgets handbook it was agreed to define the reference area as the total UAA. An important issue still remains unsolved, however. According to the handbook the balance should in principle relate to the potential fertilised area, excluding very extensive unfertilised areas, to make comparisons useful and to identify the potential risks of agricultural production to the environment in respect to nutrient surplus and deficits. After numerous discussions with stakeholders it is still unclear how to deal with extensively managed areas, for instance the non-herbaceous rough grazing areas mostly in Mediterranean regions, or mountain meadows in some other countries. The balance is an average for a country (or region) which can have both extensive and intensive agriculture. When extensively or sparsely used rough grazing or mountain areas are included, results of the balance for the country or region may be diluted, although in parts of the region the nutrient use can be quite high. This is still an open issue to which a solution needs to be found.

Climatic conditions have a big impact on the balance through the impact on yield and therefore N output. Climate and weather conditions are beyond the control of the farmer. To dampen the effect of weather conditions on the balance the results presented in this fact sheet with regards to the nutrient balance are presented not referring to a particular year but as an average for a certain period.

Subindicator: Vulnerability to phosphorus leaching/run-off

The methodology of the sub-indicator is still under development. Several factors influence the risk of P leaching and run-off such as soil erosion, drainage and sorption capacity. The retention map from the study commissioned by the European Commission in 2005 Addressing phosphorus related problems at farm practice was created based on the Soil Geographic Database of Europe. Pedotransfer rules were used to define areas at potential risk, i.e. with a low sorption capacity, high erosion rates and increased risk of accelerated drainage. Because of the unclear effect of the factor drainage and the lack of reliable data for the EU-25, efforts were focused on sorption capacity and erosion risk. Five vulnerability classes for phosphorus retention capacity were determined, whereby soils with sandy texture, poor drainage and wet water regime or high water table, with low pH and with low content of sesquioxides and/or soluble salts are most susceptible. The sorption vulnerability class was corrected through iteration for erosion, runoff and drainage processes based on soil physical properties such as soil texture, erodibility and slope.

Another factor which influences the risk of P leaching and run-off is the application of P to the soil in the present and in the past. A high value of soil test P (STP) is an indication of a strong accumulation of P in the past. Unfortunately, a database of STP as a risk indicator is not available in most EU countries.

A workshop organized by the Diredate project in Sevilla on 28 September 2010 with experts on the issue identified data needed to build the sub-indicator:

Data needed	Description	Possible source of data
Soil P status	The release of P into a mobile water phase (surface and subsurface) depends largely on the degree of P saturation in soils, which typically is related to soil test P. Similarly, the release of colloidal P is also related to soil test P.	LUCAS survey.
Soil type	Soil texture and mineralogy affect the risk of erosion and macropore transport as well as colloid mobilization. P retention capacity depends on the contents of active P sorbents and pH.	Partial data from the LUCAS survey (because LUCAS only characterizes the superficial texture of the soil).
Tillage and cropping practice	The vulnerability to erosion and surface runoff is affected by plant and residue cover, surface roughness, tramlines and traffic-induced soil compaction	AEI 21 - Soil erosion, and use of JRC models.
Fertiliser and manure use and practices	There is a risk of direct P loss from fertilisers and manures when they are not incorporated into soils during periods with high precipitation. Also, historic P applications affect soil P enrichment and hence the soil P status and degree of P saturation.	SAPM
Climate	Total rainfall and its distribution over the year affect the hydrological pathways and the vulnerability to leaching and runoff.	Available from JRC database.
Drainage	Land drainage creates shortcuts between P-enriched soils and water courses.	SAPM.
Topography	Surface and subsurface runoff depend to a large degree on terrain attributes like slope gradient and upslope contributing area as well as the distance of effective discharge and eroding areas to water courses.	Available from JRC database.
Landscape structure	The connectivity between P sources and receiving waters depends on field size and shape as well as landscape elements like hedges, roads, ditches and buffer zones.	SAPM. Administrative data possibly available as an outcome of the greening of direct payments, if landscape elements are registered in LPIS. Field size available from LPIS as well.

Context

The gross phosphorus balance provides insight into links between agricultural phosphorus use, losses of phosphorus to the environment, and the sustainable use of soil nutrient resources. A persistent surplus indicates potential environmental problems, such as phosphorus leaching resulting in pollution of drinking water and eutrophication of surface waters. A persistent deficit can impair the resource sustainability of agriculture soil through soil degradation, or soil mining, resulting in declining fertility in areas under crop or forage production.

Furthermore, EU-28 depends almost entirely on imports of phosphorus for fertilisation as there are no significant phosphate rock reserves (the main source for the production of phosphorous fertilisers) in the EU. Phosphate rock is a non-renewable natural resource. Estimations on the global availability of phosphate rock and the rate of depletion vary. Though there is uncertainty on the lifetime of remaining high quality phosphate rock reserves, there is a general consensus that the quality of remaining reserves is in decline, that phosphate layers become more difficult to access, that more waste is being generated and that costs are increasing. A sustainable use of phosphorus is needed to ensure food supply in the future and to reduce negative impacts of waste of natural resources on the environment. These include, among others, appropriate fertilisation practices, reduction of imbalances in P inputs and outputs to agricultural soils, recovery of phosphorus from sewage for fertilisation.

Policy relevance and context

International conventions of importance to phosphorus use in agriculture include inter alia UNEP/MAP (United Nations Environment Programme/Mediterranean Action Plan), CBD (Convention on Biological Diversity) and OSPAR (Oslo & Paris Convention to prevent pollution). Such international treaties often give an impetus to harmonise standards amongst all Member States of the European Union. Despite the significant off-site impact that diffuse contamination of phosphorus from agricultural land poses, there is no specific legislation that is directly concerned with the use of phosphorus in agriculture at European level. There is a lack of appropriate institutional arrangements specific to the environmental pollution of phosphorus. Aspects of the phosphorus problem are however integrated in several policy areas and related legal instruments at European level. This section provides an overview of existing regulations and directives dealing with farm-level nutrients (and phosphorus) use and production at international and European level (see also the sections on policy relevance and context in AEI 5 - Mineral fertiliser consumption).

• The Water Framework Directive (WFD) (Directive 0060/2000) is a legal obligation to protect and restore the quality of waters across Europe. Measures applied under the Water Framework Directive affecting the use of phosphorus in agriculture relate to best environmental practices and include the reduction of nutrient application, the modification of cultivation techniques, the proper handling of pesticides and fertilisers, and the prevention of soil erosion through erosion minimising soil cultivation. Most measures suggested in this context are aimed at reducing the influx of nutrients, such as nitrogen, phosphorus as well as pesticides to the groundwater as well as surface waters. The P balance surplus is a commonly used indicator for identifying areas vulnerable to nutrient pollution in the pressures and impacts analysis.
• The Nitrates Directive (ND) (Directive 0676/1991), established in 1991 aims to reduce water pollution caused or induced by nitrates from agricultural sources and prevent further such pollution. The Water Framework Directive explicitly refers to the Nitrates Directive for information on diffuse pollution of nitrates from agricultural activities and extends this to phosphates. The measures established within the Action Programmes aim to control diffuse and direct water pollution and also influence the use of phosphorus in farm practice. For instance, by limiting the annual application of nitrogen fertiliser and livestock manure, defining legally binding maximum concentrations of nitrates in drinking water and designating periods when the application is prohibited, the directive clearly aims at establishing and maintaining the natural balance of fertilisers in soils. Through these measures a massive influx of nutrients to ground- and surface water and thus potential eutrophication is prevented, while excess nutrients, oversaturation and a possible ensuing degradation is avoided at the same time. Currently the Action Programmes are no longer expected just to address losses of nitrate-nitrogen but are also judged on their ability to reduce losses of phosphorus.
• The 7th Environmental Action Programme encourages the full implementation of WFD, 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.
• Rural Development Programme (RDP): Various agri-environment measures have been established throughout the European Union directly or indirectly addressing diffuse contamination by phosphorus. Some of these measures are directed at mitigating soil erosion such as crop rotations, mulch seeding retaining stubble after harvest and ploughing restrictions. Other measures tackle the problem of excess nutrients through reduced fertiliser use. All measures that impact soil erosion and nutrient balances ultimately result in a reduction of diffuse contamination by phosphates from agricultural land.
• The Directive on Integrated Pollution Prevention and Control (IPPC) (Directive 0001/2008) introduces an integrated cross-media approach, aiming to prevent or minimise emissions to air, water and land, as well as to avoid waste production with a view to achieving a high level of environmental protection as a whole. The IPPC Directive concerns highly polluting industries, among which are intensive pig and poultry farms. A single permit based on the concept of Best Available Techniques (BAT including limit values) must include all arrangements made, including emission limit values for pollutants, for water, air and land, and may, if necessary, contain requirements for the protection of the soil and the groundwater as well as measures or waste management (Art. 9(3)) in order to continuously prevent and reduce pollution. The purpose of the IPPC Directive was to achieve integrated prevention and control of pollution arising from several categories of industrial activities. The indicative list of main polluting substances to be taken into account if they are relevant for fixing emission limit values includes oxides of nitrogen and substances which contribute to eutrophication (phosphates and nitrogen).
• Habitats Directive (Directive 0043/1992) and Birds Directive (Directive 0147/2009): The main purpose of this directive is to ensure biological diversity through the conservation of natural habitats and wild flora and fauna within the European territory, while taking into account economic, social, cultural and regional requirements. Farmers who have agricultural land in Natura 2000 sites and face restrictions due to the requirements of the Habitat-Directive are eligible to receive payments for the management of these sites by the Rural Development Regulation, which helps promote environmental-friendly farming. Depending on the specific conditions of a certain area, these include measures to reduce the use of pesticides and fertilisers, measures to mitigate the effects of soil compaction, e.g. limitations on the use of machinery or the setting of stocking limits, or measures aiming to regulate the irrigation of agricultural land.

Pollution by phosphorus is also partially covered by the Directive on Bathing Water (Directive 0007/2006), the Directive on Sewage Sludge (Directive 0278/1986) and the Directive on Urban Waste Water Treatment (Directive 0271/1991), which together with the Nitrates Directive and the Directive on Integrated Pollution Prevention Control, have been linked since 2000 in the Water Framework Directive.

Agri-environmental context

The gross phosphorus balance indicates the total potential risk to the environment (water and soil). The input side of the balance counts all P supplied to the soil. The output side of the balance presents the nutrients removed from the field by agricultural production; harvest or grazing. Sustainability could be defined as preserving and/or improving the level of production without degrading the natural resources. The harvest and grazing of crops and fodder means that P is removed from the soil. To sustain soil fertility this removal of P should be compensated. Fertilisers and manure are therefore imperative to supply the crops with the necessary P for growing.

Depending on the soil P capacity, excessive P can be stored in the soil. Not all of P in fertilisers and manure are directly available to the plant, a part is converted from active P to fixed P. The active P pool is the main source of available P for crops, whereas the fixed P pool contains inorganic phosphate compounds that are very insoluble and organic compounds that are resistant to mineralisation by microorganisms in the soil. Phosphate in this pool may remain in soils for years without being made available to plants and may have very little impact on the fertility of a soil. Depleting the active pool through crop uptake may cause some of the fixed P to slowly become active. The storage capacity of the soil, however, depends on soil characteristics like soil texture. An important aspect of the ability of a soil to hold phosphate is that a soil cannot hold increasing amounts of phosphate in the solid phase without also increasing soil solution phosphate. Increased amounts of phosphate in solution will potentially cause more phosphate to be lost to water running over the soil surface or leaching through the soil. Loading soils with very high levels of phosphate will generally not hurt crops but may result in increased phosphate movement to nearby bodies of water. It has been estimated that 25 % or less of P applied annually is actually taken up by the growing crop; the remaining 75 % becomes bond in the soil profile or is lost to water. The crop uptake of P is in sharp contrast to the crop use of N and K fertilisers, where the recovery in the season of application can be as high as 80 %. Yield and therefore the uptake of P by crops is not only determined by inputs but also by uncontrollable factors like type of soil and climate.

The estimated P surplus represents the potential risks to water and soil. The actual P loss from agricultural land to surface waters is a complex function of climate, topography, soil type, soil P status, P fertilisation, and land management. These factors vary greatly in space and over the year, and the hydrological pathways for P losses also vary greatly in space and time. The effects of these individual factors on P loss from agricultural land to surface waters are rather well understood, but in combination the understanding is less well developed. As a consequence, current simulation models do not yet simulate the actual P loss from agricultural land to surface waters very accurately. Further, the ecological effect of P from agricultural land in surface waters depends on the 'bio-availability' of the P. A significant fraction of the P from agricultural land that is lost to surface waters is particulate P and the availability of this P to growing organisms in surface waters is much less than dissolved reactive P, at least in the short term. Hence, ‘the pollution effect’ of P lost from agricultural land to surface waters does not depend on the total P loss but on the fraction 'reactive P'.

The accumulated amount of P represents a larger actual risk for the environment than the amount of P which is applied yearly, or the surplus on today’s balance. However, the future risk is strongly influenced by the P balance of today and the near future, in combination with the capacity of a soil to bind P. This contrasts with nitrogen; the cumulative N balance of the past is much less relevant since N hardly accumulates in soils. This is why the main indicator on its own is not sufficient to indicate areas at risk of phosphorus pollution.

The gross phosphorus balance also gives information on the dependence on mineral fertilisers. Phosphorus, contrary to Nitrogen, is a finite resource – in the sense that phosphate ores are becoming depleted – and after being used in agriculture, the mineral ultimately becomes unavailable for reuse, or can be reused only to a very limited extent. Phosphorus builds up in agricultural soils, it ends up in the sludge from water treatment plants – which is largely incinerated and thereby removed from the agricultural cycle – but mostly it is eroded, thereby ending up in the sediments of lakes, coastal seas and the ocean. Recycling from ocean sediments takes place during a period of millions of years.

The natural level of phosphate in the soil is very low and limits plant growth. Before the industrial revolution, phosphate was a limiting factor nearly everywhere on Earth. A breakthrough occurred in the 19th century by means of the external application of phosphate as a fertiliser, where the mineral originated outside the area to be fertilised. As a result of this external source, the local phosphate cycles were broken; at the same time, this created the basis for a potential shortage in the future. This external application of phosphate (and other fertilisers) from external sources was one of the preconditions for the increase in the world population from approximately 1 billion people in 1850 to the current population of 6.8 billion. The EU is almost entirely dependent on imports of phosphate; very little is mined within the EU. Import takes place in two forms: artificial fertiliser and animal feed. In total, 1.6 Mt P per year is imported into the EU, where the phosphate contained in animal feed ultimately ends up in animal manure. The total phosphorus import of the EU concerns nearly 10 % of the entire world production of artificial phosphate fertiliser. It is important to note that the EU, other than is usually assumed, is not at all self-sufficient in food production due to this phosphate dependency.

See also

• Agri-environmental indicators (online publication)

Further Eurostat information

Publications

• Agriculture, forestry and fishery statistics - 2016 edition
• Environmental statistics and accounts in Europe - 2010 edition
• Food: from farm to fork statistics - 2011 edition

Database

• Agriculture, see:

Agriculture and environment (aei)

Gross nutrient balance (aei_pr_gnb)

Dedicated section

• Agri-Environmental Indicators

Methodology / Metadata

• Eurostat/OECD Nutrient Balance Handbook
• Gross nutrient balance (ei_pr_gnb_esms)

Source data for tables, figures and maps (MS Excel)

• Download Excel File 

Other information

• Commission Communication COM(2006)508 final - Development of agri-environmental indicators for monitoring the integration of environmental concerns into the common agricultural policy
• Agri-Environmental Indicators, see:

Legislation: Commission Staff working document accompanying COM(2006)508 final

External links

• European Commission - Agriculture and Rural Development

• Agri-environmental indicators
• The Common Agricultural Policy (CAP)

• European Commission – Environment

• Water

• European Commission – Climate Action

• Climate strategies & targets

• OECD - Agri-environmental Indicators and Policies
• European Sustainable Phosphorus Platform
• Our Nutrient World
• United Nations Environment Programme (UNEP)