To make the most effective use of resources and maximise the value of actions across the catchment, evidence is vital. To identify the most effect interventions to make improvements within catchments we need to understand how phosphorus is entering our rivers. We need then to understand how phosphorus is used in agriculture, the wider food system, and the impact on the environment. We also need to understand how changes in land use, e.g. grassland conversion to arable, may be contributing to the wider impact.
The element phosphorus is an essential nutrient for life, but excessive amounts can cause eutrophication (too much nutrient) in freshwater, which can lead to algal blooms. There are numerous chemical compounds that contain phosphorus.
Total Phosphorus
Contains all forms of phosphorus, that which is crop available (i.e. the readily available P in the soil) and that which is not immediately plant available but is vulnerable to environmental loss (i.e. attached to soil particles in surface runoff processes). The ‘total’ amount of phosphorus legacy in the ‘bank’ is many times greater than the amount measured in soil tests as available to plants and which is used to determine fertiliser applications. Total phosphorus is useful for assessing catchment conditions and can be used in conjunction with flow rates to provide load-based estimates of phosphorus being transported downstream.
Watch the new video Focus on Phosphorus
Orthophosphate
Orthophosphate is often referred to as phosphate and it can be used by plants (including algae) immediately. Monitoring phosphate in water is useful because it provides a good indication of ecological risk such as eutrophication. Phosphate is routinely monitored by the EA for the Water Framework Directive and Special Areas of Conservation assessments.
Source Apportionment
Source apportionment modelled analysis suggests that over 72 -74% of the phosphate (Orthophosphate) load comes from rural land use, 21 – 23% from sewage treatment works, <1 – 2% storm overflows, and 3 – 5% from other sources.
RePhoKUs
Building the evidence base is key to driving positive change. We need to understand the phosphorus story. The Lancaster University RePhoKUs team are a highly respected academic team whose work aims to re-focus phosphorus use in the UK food system to achieve sustainable use and deliver valued ecosystem services such as clean water and biodiversity.
Manure is a source of phosphorus, however in the UK arable cropping areas rely on imports of mineral phosphate to manage food production. The UK does not have its own source of mineable rock phosphate and imports from countries like Morocco, China and Russia. It takes millions of years for these rocks to form, and available supplies are expected to decline by 2050 as demand for food increases in line with the growth of the global population. This makes our agriculture and food supply vulnerable to price changes and shortages. Import prices of phosphorus increased sharply with the war in the Ukraine. Phosphorus is an essential crop nutrient. If crops cannot get enough phosphorus, we cannot produce the quantity and quality of food we need, threatening food security.
Read the blog Phosphorus: the Hidden Bedrock of the UK food system
The UK imports around 174,000 tonnes of phosphorus annually, less than half of which (74,000 tonnes) is productively used, that is converted into food and other commodities. Demand is expected to increase with a growing population. Phosphorus use in the UK is highly inefficient. Applying surplus phosphorus to land is a waste of valuable resource and damages the environment.
Phosphorus leakage from land to water causes widespread and costly pollution (worth £39.5 billion).
The RePhoKUs report provides vital evidence to increase our understanding around some of the key challenges in making improvements to the condition of the river. The report focuses on the movement and loading of Total Phosphorus. A strong link between catchment phosphorus input pressures, manure phosphorus loadings to the land surface and build-up of soil phosphorus across the English part of the Wye was highlighted. Modelling suggests farming in the catchment generates an annual phosphorus surplus of 2,000 – 3,000 tonnes, which is accumulating in the catchment soils. This amount of unused phosphorus is nearly 60% greater than the national average and is driven by the large amounts of livestock manure produced in the catchment. Wye soils are more likely to leak phosphorus than many other soils because of their poor ability to hold onto the phosphorus applied in fertilisers and manures and pose a high risk of losing phosphorus to draining streams.
RePhoKUs advises that to achieve ‘a catchment zero phosphorus surplus, or encouraging agriculture to draw down legacy reserves, requires a level of governance that is beyond the responsibility of the individual farmer or industry. It is a collective catchment stakeholder responsibility.’
The fertiliser industry estimates that only 5% of phosphorus is sourced from recovered materials. Transportation costs and the economies of scale for technology are challenges when it comes to increasing the usage of recycled phosphorus fertilisers. The cost of change is a real barrier for many individual farmers. New products that match the markets requirements need to be developed. Given the costs and impracticalities of regularly transporting bulky livestock manures long distances, this means that technological solutions are needed to either make livestock manures more transportable or recover inorganic phosphorus from manures and biosolids in a fertiliser-grade form (e.g. as struvite or calcium phosphate)
Find out more about the RePhoKUs project.
Soil Phosphorus Status and Water Quality in the River Wye
The Environment Agency has commissioned the team at Lancaster University to undertake a further three studies to investigate potential links between livestock manure, surplus phosphorus in manure and the potential linkages between surplus phosphorus in soil from manure spreading and phosphorus concentration in the rivers and tributaries. The results of the research could help to enable better management of phosphorus loss to water through regulation and best practice. |
Phase One
This study scoped, collated and/or analysed available data on nutrient balances, soil phosphorus status, land runoff phosphorus concentrations and river nutrient concentrations in the Eastern half of the Wye catchment area. The report investigated the feasibility of linking manure-driven nutrient accumulation, soil phosphorus status and river nutrient concentrations. Looking at what further research and monitoring work is needed to improve the evidence base linking livestock farming to water quality impacts.
The report highlights that there is a strong link between catchment phosphorus input pressures, manure phosphorus loadings to the land surface and build-up of soil phosphorus across the English part of the Wye.
Read the phase one Study: Soil Phosphorus Status and Water Quality in the River Wye
Phase Two
This study aimed to develop the evidence base between livestock farming to phosphorus surpluses, soil phosphorus status and water quality impacts in the Wye catchment. The report also aimed to build understanding of the potential impact on phosphorus surpluses and water quality when there is a change to land use.
Livestock farming has had a major impact on land use patterns and phosphorus cycling in the Wye catchment over the last 150 years, traditionally with cattle (dairy and beef) and sheep farming but more recently due to the rapid expansion of the poultry industry. An historic analysis of census-derived land use and livestock numbers indicates the Wye catchment has been in phosphorus surplus for the last 150 years.
Historic applications of phosphorus indicate that more has been added to the land than crops can use. The soil phosphorus legacy, the amount of phosphorus we know that was applied to the land which could not have been used is equivalent to 1.86 tonnes per hectare in the arable and productive grassland. Only 30-60% of this phosphorus legacy can be accounted for in the top 30cm of soil. So where is the missing phosphorus?
Read the phase two study: Land Use Change and Phosphorus Balances in the Wye Catchment
Phase Three
Further investigation is vital, and Phase 3 work will focus on phosphorus sampling in topsoil at depths of 0-15, 15-30, 30-60 and 60-90 cm. This will shed light on how much of that legacy phosphorus remains in the soil profile.
Phase 3 is a preliminary investigation. The data collected will be valuable because we can then look at the totals to better understand the amount of phosphorus retained and lost over time.
It will improve our evidence and help to answer the question: How much phosphorus could be leaking into the River Wye and its tributaries?
What we learn can be used to target interventions and drive innovation to start to turn the tide on the declining state of the river.
RePhoKUs Wye Catchment Challenges
The RePhoKUs study for the Wye Catchment highlighted many challenges in making water quality improvements. The issues are complex and there is no quick or easy fix. This problem will require a deeper understanding of the Wye as a system and the interactions between all its components to deliver new and innovative interventions. The Wye has been in surplus phosphorus for 150 years and year after year more phosphorus than is needed is added to land.
Phosphorus availability varies throughout the UK and identifying areas of surplus production and deficit is an important factor in addressing the problems. Researchers and soil testing labs could play a key role in mapping out UK phosphorus requirements.
RePhoKUs suggested reducing phosphorus inputs into the catchment might be achieved by lowering demand for example by destocking or through human dietary change, by recovering phosphorus from manures to substitute for imports of fertilisers and feed supplements, by utilising legacy soil phosphorus reserves instead of applying fresh phosphorus, or a combination of these. The National Food Strategy (National Food Strategy, 2021) recommends cutting meat consumption by 30% over the next decade but this requires national policy development, and reducing livestock numbers without clear alternatives may also impact on rural livelihoods and the economy.
Visit the RePhoKUs web pages
To make the most effective use of resources and maximise the value of actions across the catchment, evidence is vital. To identify the most effect interventions to make improvements within catchments we need to understand how phosphorus is entering our rivers. We need then to understand how phosphorus is used in agriculture, the wider food system, and the impact on the environment. We also need to understand how changes in land use, e.g. grassland conversion to arable, may be contributing to the wider impact.
The element phosphorus is an essential nutrient for life, but excessive amounts can cause eutrophication (too much nutrient) in freshwater, which can lead to algal blooms. There are numerous chemical compounds that contain phosphorus.
Total Phosphorus
Contains all forms of phosphorus, that which is crop available (i.e. the readily available P in the soil) and that which is not immediately plant available but is vulnerable to environmental loss (i.e. attached to soil particles in surface runoff processes). The ‘total’ amount of phosphorus legacy in the ‘bank’ is many times greater than the amount measured in soil tests as available to plants and which is used to determine fertiliser applications. Total phosphorus is useful for assessing catchment conditions and can be used in conjunction with flow rates to provide load-based estimates of phosphorus being transported downstream.
Watch the new video Focus on Phosphorus
Orthophosphate
Orthophosphate is often referred to as phosphate and it can be used by plants (including algae) immediately. Monitoring phosphate in water is useful because it provides a good indication of ecological risk such as eutrophication. Phosphate is routinely monitored by the EA for the Water Framework Directive and Special Areas of Conservation assessments.
Source Apportionment
Source apportionment modelled analysis suggests that over 72 -74% of the phosphate (Orthophosphate) load comes from rural land use, 21 – 23% from sewage treatment works, <1 – 2% storm overflows, and 3 – 5% from other sources.
RePhoKUs
Building the evidence base is key to driving positive change. We need to understand the phosphorus story. The Lancaster University RePhoKUs team are a highly respected academic team whose work aims to re-focus phosphorus use in the UK food system to achieve sustainable use and deliver valued ecosystem services such as clean water and biodiversity.
Manure is a source of phosphorus, however in the UK arable cropping areas rely on imports of mineral phosphate to manage food production. The UK does not have its own source of mineable rock phosphate and imports from countries like Morocco, China and Russia. It takes millions of years for these rocks to form, and available supplies are expected to decline by 2050 as demand for food increases in line with the growth of the global population. This makes our agriculture and food supply vulnerable to price changes and shortages. Import prices of phosphorus increased sharply with the war in the Ukraine. Phosphorus is an essential crop nutrient. If crops cannot get enough phosphorus, we cannot produce the quantity and quality of food we need, threatening food security.
Read the blog Phosphorus: the Hidden Bedrock of the UK food system
The UK imports around 174,000 tonnes of phosphorus annually, less than half of which (74,000 tonnes) is productively used, that is converted into food and other commodities. Demand is expected to increase with a growing population. Phosphorus use in the UK is highly inefficient. Applying surplus phosphorus to land is a waste of valuable resource and damages the environment.
Phosphorus leakage from land to water causes widespread and costly pollution (worth £39.5 billion).
The RePhoKUs report provides vital evidence to increase our understanding around some of the key challenges in making improvements to the condition of the river. The report focuses on the movement and loading of Total Phosphorus. A strong link between catchment phosphorus input pressures, manure phosphorus loadings to the land surface and build-up of soil phosphorus across the English part of the Wye was highlighted. Modelling suggests farming in the catchment generates an annual phosphorus surplus of 2,000 – 3,000 tonnes, which is accumulating in the catchment soils. This amount of unused phosphorus is nearly 60% greater than the national average and is driven by the large amounts of livestock manure produced in the catchment. Wye soils are more likely to leak phosphorus than many other soils because of their poor ability to hold onto the phosphorus applied in fertilisers and manures and pose a high risk of losing phosphorus to draining streams.
RePhoKUs advises that to achieve ‘a catchment zero phosphorus surplus, or encouraging agriculture to draw down legacy reserves, requires a level of governance that is beyond the responsibility of the individual farmer or industry. It is a collective catchment stakeholder responsibility.’
The fertiliser industry estimates that only 5% of phosphorus is sourced from recovered materials. Transportation costs and the economies of scale for technology are challenges when it comes to increasing the usage of recycled phosphorus fertilisers. The cost of change is a real barrier for many individual farmers. New products that match the markets requirements need to be developed. Given the costs and impracticalities of regularly transporting bulky livestock manures long distances, this means that technological solutions are needed to either make livestock manures more transportable or recover inorganic phosphorus from manures and biosolids in a fertiliser-grade form (e.g. as struvite or calcium phosphate)
Find out more about the RePhoKUs project.
Soil Phosphorus Status and Water Quality in the River Wye
The Environment Agency has commissioned the team at Lancaster University to undertake a further three studies to investigate potential links between livestock manure, surplus phosphorus in manure and the potential linkages between surplus phosphorus in soil from manure spreading and phosphorus concentration in the rivers and tributaries. The results of the research could help to enable better management of phosphorus loss to water through regulation and best practice. |
Phase One
This study scoped, collated and/or analysed available data on nutrient balances, soil phosphorus status, land runoff phosphorus concentrations and river nutrient concentrations in the Eastern half of the Wye catchment area. The report investigated the feasibility of linking manure-driven nutrient accumulation, soil phosphorus status and river nutrient concentrations. Looking at what further research and monitoring work is needed to improve the evidence base linking livestock farming to water quality impacts.
The report highlights that there is a strong link between catchment phosphorus input pressures, manure phosphorus loadings to the land surface and build-up of soil phosphorus across the English part of the Wye.
Read the phase one Study: Soil Phosphorus Status and Water Quality in the River Wye
Phase Two
This study aimed to develop the evidence base between livestock farming to phosphorus surpluses, soil phosphorus status and water quality impacts in the Wye catchment. The report also aimed to build understanding of the potential impact on phosphorus surpluses and water quality when there is a change to land use.
Livestock farming has had a major impact on land use patterns and phosphorus cycling in the Wye catchment over the last 150 years, traditionally with cattle (dairy and beef) and sheep farming but more recently due to the rapid expansion of the poultry industry. An historic analysis of census-derived land use and livestock numbers indicates the Wye catchment has been in phosphorus surplus for the last 150 years.
Historic applications of phosphorus indicate that more has been added to the land than crops can use. The soil phosphorus legacy, the amount of phosphorus we know that was applied to the land which could not have been used is equivalent to 1.86 tonnes per hectare in the arable and productive grassland. Only 30-60% of this phosphorus legacy can be accounted for in the top 30cm of soil. So where is the missing phosphorus?
Read the phase two study: Land Use Change and Phosphorus Balances in the Wye Catchment
Phase Three
Further investigation is vital, and Phase 3 work will focus on phosphorus sampling in topsoil at depths of 0-15, 15-30, 30-60 and 60-90 cm. This will shed light on how much of that legacy phosphorus remains in the soil profile.
Phase 3 is a preliminary investigation. The data collected will be valuable because we can then look at the totals to better understand the amount of phosphorus retained and lost over time.
It will improve our evidence and help to answer the question: How much phosphorus could be leaking into the River Wye and its tributaries?
What we learn can be used to target interventions and drive innovation to start to turn the tide on the declining state of the river.
RePhoKUs Wye Catchment Challenges
The RePhoKUs study for the Wye Catchment highlighted many challenges in making water quality improvements. The issues are complex and there is no quick or easy fix. This problem will require a deeper understanding of the Wye as a system and the interactions between all its components to deliver new and innovative interventions. The Wye has been in surplus phosphorus for 150 years and year after year more phosphorus than is needed is added to land.
Phosphorus availability varies throughout the UK and identifying areas of surplus production and deficit is an important factor in addressing the problems. Researchers and soil testing labs could play a key role in mapping out UK phosphorus requirements.
RePhoKUs suggested reducing phosphorus inputs into the catchment might be achieved by lowering demand for example by destocking or through human dietary change, by recovering phosphorus from manures to substitute for imports of fertilisers and feed supplements, by utilising legacy soil phosphorus reserves instead of applying fresh phosphorus, or a combination of these. The National Food Strategy (National Food Strategy, 2021) recommends cutting meat consumption by 30% over the next decade but this requires national policy development, and reducing livestock numbers without clear alternatives may also impact on rural livelihoods and the economy.
Visit the RePhoKUs web pages
