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.

Full article

Key messages

• Phosphorous is an important plant nutrient, essential for world-wide food security. It is used in agriculture as fertiliser, and the EU is almost entirely dependent on imports to fulfill its need. But phosphorus is used in an unsustainable way; via fertilizers, sewage and animal manure, phosphorus and other nutrients is lost to water bodies and cause pollution.
• 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 gross phosphorous balance 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 gross phosphorous balance 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.

Analysis at EU level

The gross phosphorous balance 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 phosphorus 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.

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 gross phosphorous balance 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 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.

Source data for tables and graphs

Data sources 

Indicator definition

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

This indicator has links to a number of other AEI indicators that describe developments in some of the main contributory factors.

Data used and methodology

Due to missing data nutrient balances have been estimated by Eurostat for several countries and several years (Table 1). These estimations were based on data available in Eurostat's dissemination database, international public data collections, and published research, and confirmed with the countries in question as reasonable estimates. For 2015, no detailed estimates have been made and therefore no detailed analysis covers this year.

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 is usually the UAA. It should be noted that some countries use slightly different methodologies; the United Kingdom and Spain fall into this group. It means that the time series are comparable within the countries, but the individual values should not be compared with other countries' individual values.

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;

The outputs of the gross phosphorus balance are:

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

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

• Crop residues removed from the field.

The phosphorus inputs and phosphorus outputs are estimated for each item of the balance from basic data multiplied with coefficients to convert the data in phosphorus 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. They are either given by the country, or estimated by Eurostat. A European uniform methodology and validation procedure to estimate 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 and in updating procedures. In order 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 any changes in farming practices.

Climatic conditions have a big impact on the balance through the impact on yield and therefore phosphorus 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.

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.

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 phosphorous inputs and outputs to agricultural soils, recovery of phosphorus from sewage for fertilisation.

Policy relevance

The EU-28 depends entirely on imports of phosphorus, and there are only minor phosphate rock reserves (the main source for the production of phosphorous fertilisers) in the EU. Therefore, phosphorous and phosphate rock are defined as a Critical Raw Material for the EU. Phosphate rock is a non-renewable natural resource. The European Commission has made a legislative proposal on fertilisers aiming to create a genuine single market for fertilisers made from secondary raw materials (in particular recovered nutrients), thereby turning waste management problems into economic opportunities. The proposed rules can make the fertilisers sector less dependent on imports of critical, primary raw materials such as phosphate, which can also be recovered from domestic organic waste. This proposal is a part of the Circular Economy Action Plan.

The 7th Environment Action Programme (EAP) calls for further efforts to manage the nutrient cycle in a more sustainable way and to improve efficiency in the use of fertilisers. Better source control, and the recovery of waste phosphorus are called for.

The Habitats Directive and the Birds Directive aim to ensure biological diversity through the conservation of natural habitats and wild flora and fauna within the European territory. Farmers who have agricultural land in Natura 2000 sites may face restrictions in using their land, such as reduction in the use of fertilisers.

Within the Common Agriculture Policy, 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.

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 phosphorous 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 phosphorus is removed from the soil. To sustain soil fertility this removal of phosphorus should be compensated. Fertilisers and manure are therefore imperative to supply the crops with the necessary phosphorus for growing.

Depending on the soil phosphorus capacity, excessive phosphorus can be stored in the soil. Not all of phosphorus in fertilisers and manure are directly available to the plant, a part is converted from active phosphorus to fixed phosphorus. The active phosphorus pool is the main source of available phosphorus for crops, whereas the fixed phosphorus 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 phosphate 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 phosphorous applied annually is actually taken up by the growing crop; the remaining 75 % becomes bound in the soil profile or is lost to water. The crop uptake of phosphorous is in sharp contrast to the crop use of nitrogen and potassium fertilisers, where the recovery in the season of application can be as high as 80 %. Yield and therefore the uptake of phosphorus by crops is not only determined by inputs but also by uncontrollable factors like type of soil and climate.

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

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

Vulnerability to phosphorus leaching/run-off

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 has not been developed. The vulnerability to phosphorus 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. 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. Phosphorus accumulation in soils might increase concentrations of dissolved and colloidal phosphorus in drainage. In a 2005 study commissioned by the European Commission called Addressing phosphorus related problems at farm practice , areas at risk of encountering potential phosphorus excess were indicated 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. </context>

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External links

• Agri-environmental indicator - Gross Nitrogen Balance
• Agri-environmental indicators - fact sheets

• Agriculture, forestry and fishery statistics - 2017 edition

• Agriculture and Environment, see:

Gross Nutrient Balance (aei_pr_gnb)

• Agri-environmental indicators, see:

Gross nutrient balance on agricultural land by nutrient (sdg_02_50)

• Agri-Environmental Indicators

• Eurostat/OECD Nitrogen Budgets handbook
• Gross nutrient balance (aei_pr_gnb_esms)
• ESS agreement on data collection

• 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

• European Commission - Agriculture and Rural Development

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

• European Commission – Environment

• Water

• OECD - Agri-environmental Indicators and Policies

Notes