Exploiting root exudation of organic acids and phytases to enhance plant utilisation of soil phosphorus

Lead Research Organisation: Lancaster University
Department Name: Lancaster Environment Centre

Abstract

Phosphorus (P) is a non-renewable resource, essential for crop production. Uncertainties over mineral P supplies coupled with concerns for food security and environmental impact of P on waters all necessitate an improvement in agronomic P efficiencies, based on sound knowledge of the range of P forms in soils. Our research is different to previous approaches to recover P from soils in that it focuses on the organic P (Po) components and uses a novel combination of root exudates from different plants to solubilise organic P and make it bioavailable as inorganic orthophosphate.

The two fundamental problems associated with the use of soil organic P by plants are that much of it is strongly attached to soil particles and therefore inaccessible to plants, and secondly, even when not firmly attached to soil particles, the forms in which it exists are not readily available for plant uptake. Some plants possess traits that can help access organic P in soils; firstly some plants can produce organic acids from their roots, which can release the P attached to soil particles, and secondly some can release phosphatases (e.g. phytase), which can hydrolyse the organic P into forms which plants can take-up. However, crop plants generally do not possess both these traits and so combinations of plants are required, each carrying out a different role. Systems that rely on clover undersown into cereal crops to provide nitrogen (N) to the current crop, act as an overwinter green manure, and to provide N to following crops are fairly common in organic farming enterprises. We have clover lines which can produce phytase required to mineralize organic P, while some strains of barley have been shown to release organic acids, making the organic P available for mineralisation. We will investigate a clover/barley bi-cropping system as an exemplar sustainable alternative to intensive applications of P and N fertilizers, thus potentially making the arable system more efficient both economically and environmentally. Thus we shall test the overarching hypothesis that: Cropping systems with roots exuding both organic acid anions and phytase can facilitate more sustainable agricultural production by accessing soil organic P forms.

Specifically, we propose to investigate and understand the role of organic acids and phosphatases in plant mixtures in accessing the organic P from the inositol phosphate pool. We shall then explore what happens to these organic P forms in the soils and the rhizosphere and examine their potential (or otherwise) for leaching from the soil to surface waters where they may cause eutrophication. A range of experiments will be carried out to identify potentially suitable strains of barley and clover for such a system, followed by experiments incorporating different combinations of these strains, grown in soil, to assess what combinations can most efficiently access different forms of organic P, while minimizing leaching losses. By increasing the amount of P utilized from the P stored in soils we can reduce the reliance on inorganic fertilisers, increasing agricultural sustainability and improving our ability to deliver food security in coming decades.

Technical Summary

Organic phosphorus is a common constituent of the P in many soils and comprises mostly of esters of fully oxidised P where P is attached to C through an O atom. Other compounds such as phosphonates and organic polyphosphates occur in lesser amounts. Our appreciation of the extent to which crop plants can utilise organic P pools in soils is limited. The overarching aim of the project is to test the hypothesis that: Cropping systems with roots exuding both organic acid anions and phytase can facilitate more sustainable agricultural production by accessing soil organic P forms.

We will investigate and attempt to understand the role of organic acid anions and phosphatases in exemplar plant mixtures in accessing organic P in soils. We shall then explore what happens to these compounds in the soils and the rhizosphere. A range of experiments will be carried out to identify potentially suitable strains of barley and clover for such a system, followed by experiments incorporating different combinations of these strains, grown in soil, to assess what combinations can most efficiently access different forms of organic P, while minimizing the losses of P via leachate. Experiments and techniques employed will include screening of plant populations for abilities to exude organic acids and phosphatases using anion exchange resins (AERs) and DGT (diffusive gradients in thin films), HPLC, enzyme hydrolysis and 31P nuclear magnetic resonance (NMR) analysis, for identification of organic P compounds and groups in soil extracts and soil water.

Planned Impact

The subject of this proposal is highly relevant to current policy in the UK, with innovation and efficiency of nutrient use being highlighted as one of the key factors in developing both national and global sustainable food security. This was the subject of a recent Foresight Workshop on 'Stimulating Innovation and Efficiency in Fertiliser Production and Use' (20th September 2012), convened by the UK Government Office for Science and attended by two of the proposing group. At the workshop the Government Chief Scientific Advisor, Sir John Beddington, highlighted the urgent need to address food production issues of which sustainable nutrient use is a vital component, but stated that governments have been slow to realise this urgency and to acknowledge the indisputable role fertiliser use will play. One of the conclusions from the workshop, attended by leading UK and international academic researchers and fertiliser industry specialists, was that improved phosphorus acquisition traits in crops and cropping systems will play an important role in achieving these goals.

This proposed project will explore technologies to improve crop productivity and nutrient use efficiency by enhancing the availability to plants of organic P in soils (which is relatively unavailable, but plentiful), whilst also minimising any potential negative environmental consequences. It therefore has implications to help agricultural producers and scientists, fertiliser suppliers, crop breeders, land and catchment managers through to policy makers. Knowledge of organic P species in soils is fundamental to the development of new plant varieties able to hydrolyse the organic P resources which may occur in different soil types and therefore this project is of particular interest to plant breeders. Additionally, it will assist with development of cropping techniques such as bi-cropping for maximizing the benefits of different plant traits.

Ultimately this work could potentially inform policy through providing information on how to maximize crop yields while minimizing fertiliser inputs. Results could influence the way in which cropping systems are considered in the future both nationally and internationally, providing some fundamental science supporting their development, based on more than just yield/productivity, but also on the specific soil/plant processes involved. In the long term this work could contribute to the nation's wealth by providing guidance on more nutrient efficient cropping techniques and indicating which traits in plants should be developed, and how they may work in tandem to maximize productivity while minimizing fertiliser usage. It may also mean that the nation becomes less reliant on the increasingly scarce global mineral P resources, which are not only becoming more expensive, but also in a time of political instability, could potentially become inaccessible. Internationally, the approaches developed here could mean increases in crop yields in under-developed regions where fertilisers are unavailable. The basic principle behind the science proposed here is relatively simple to convey, and in combination with its strategic importance to BBSRC with regard to Food Security, makes it an ideal topic to showcase to the public. This will be done at all the participating Institutes' Open days/School Science Week events, meaning it would not only have benefits to the current scientific community, but may also stimulate a new generation of scientists into this field of research. This project addresses the BBSRC strategic research priority areas of crop science (food security) and global security.

Publications


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Menezes-Blackburn D (2016) A Holistic Approach to Understanding the Desorption of Phosphorus in Soils. in Environmental science & technology
 
Description The interaction of phytases, Po and and organic acids with the soil solid phase was investigated using a combination of plant cultivation and soil analysis techniques, including Diffusive Gradients Thin Films (DGT), soil phosphatase zymography, and the analysis of P fractions and species using solution 31P NMR spectroscopy, extract, and enzyme-based soil assays. A range of experiments were conducted to identify cultivars of barley (Hordeum vulgare L.) and legume species with complementary root exudation and morphological characteristics for intercropping. Through facilitation and improved cycling of P in soils, the intercropped barley and legume lines are expected to facilitate sustainable agricultural production through improved P use efficiency, possible by acquiring soil organic P. An intercropping experiment was designed based on the results of an initial barley and legume screening study, which recommended that barley cultivars and legume species with the most disparate exudate and morphological root characteristics would experience fewer competitive interactions and may therefore facilitate the acquisition of P from soils. The intercropping study with barley and legumes showed that complementarity occurred in some but not all plant combinations and depended on soil P availability, whereby complementarity was greatest at the sub-critical P requirement for barley. Using model tobacco plant lines with heterologous expression of fungal phytases (Phy) and Arabidopsis citrate transporters (Cit), the beneficial interaction of citrate and phytase exudation was demonstrated in a soil with limited P availability (Podzol). Positive growth effects between intercropped (Int) citrate- and phytase-exuding plant lines coincided with the depletion of organic P in rhizosphere soils when the roots of two plants were intermingled. An experiment was designed to investigate the importance of root intermingling in the development of complementarity between the citrate- and phytase-exuding tobacco plant lines. As observed in the first study with tobacco, positive complementarity occurred in the P limited soil when Cit and Phy plant roots intermingled. However, when plant roots were separated by a permeable mesh barrier, complementarity diminished. Whether complementarity occurred in separated root treatments depended on the source and relative mobility of the phytase being expressed. The Peniophora lycii phyA is expected to be relatively more mobile in soil (pH 5) compared to the Aspergillus niger phyA based on differences in isoelectric point. Only in Cit+Phy plant combinations containing the more mobile phytase was positive complementarity observed in separated root treatments. This study also showed that complementarity between Cit and Phy plants only occurs under conditions of limited soil P availability and scales with the rate of citrate efflux in Cit plants. Importantly, gains in shoot P content due to the interaction of these exudates in a P limited soil (+0.1-0.2% shoot P) would be adequate for many crop species to transition from physiological deficient to sufficient in P. The interaction of citrate and phytase exudates was expected to promote the depletion of organic P forms in the rhizosphere. Specifically, tobacco plants expressing the Phy exudation trait were expected to promote the depletion of soil phytate beyond that of wild-type or vector control plant lines. Analysis of rhizosphere soils with solution 31P nuclear magnetic resonance spectroscopy showed that the Phy trait did not lead to a greater depletion of soil organic P (in comparison to null vector and wild-type plants) when plants were grown in a soil with adequate P in plant available P (Cambisol). Pleiotropic effects of the vector plant line, including a larger root biomass, and differences in soil pH among plant treatments were likely factors effected this outcome. However, in a limited available P soil, 31P NMR analysis revealed a greater depletion of soil organic P (albeit not phytate specifically) and increase in plant available orthophosphate in soils planted with Cit and Phy tobacco combinations. The intercropped plant combinations also accumulated more shoot P than the other plant treatments, suggesting that organic P converted to orthophosphate in soil was utilised for growth by these plants. Collectively, the experiments conducted with tobacco indicate that the interaction of citrate and phytase exudates promotes the conversion of soil organic P for plant P uptake, but only when soil available P is limited. The development of complementarity in barley-legume intercropping systems also only occurred with limited soil P availability. The development of positive complementarity and gains in shoot P content could be sufficient to improve plant P nutrition in cropping systems but will depend on exudate characteristics (rate of efflux, enzyme mobility) and distribution of exudates in soil. Furthermore, organic anion and phosphatase exudate-based strategies for improving the acquisition of soil P by plants appear to be the most effective in limited available P soils, which are also abundant in organic P. Using the DGT method applied in soils, studies of P bioavailability, mobility and resupply from solid phase were performed in 32 UK soils and a set of controlled experiments using 2 UK soils were conducted to investigate the effect of various organic anions on solid-to-solution phase partitioning of phosphorus. This allowed a better comprehension of the phosphorus chemistry with deep insights on its agronomic use across a wide range of different UK soils and plant exudation conditions.
Exploitation Route First manuscript was published in Environmental Science & Technology (Just accepted - available online only- http://pubs.acs.org/doi/abs/10.1021/acs.est.5b05395). (IF 5.3)
Other 4 manuscripts with key findings are being prepared to be published in scientific journals.
Sectors Agriculture, Food and Drink,Environment,Other
URL http://soilorganicp.com/
 
Description First manuscript was published in Environmental Science & Technology (ACS Publications) and other findings are being prepared for publication and will soon be available for the scientific community and general public.
First Year Of Impact 2015
Sector Agriculture, Food and Drink,Environment
 
Description EU consultation on P Sustainability
Geographic Reach Asia 
Policy Influence Type Participation in a national consultation
URL http://ec.europa.eu/environment/consultations/pdf/phosphorus/EN.pdf
 
Description BBSRC PARTNERSHIP AWARD FUNDING
Amount £20,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 08/2014 
End 06/2016
 
Description Lancaster University MSc Student
Amount £6,000 (GBP)
Organisation Lancaster University 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 06/2014 
End 10/2014
 
Description STARS PhD studentship
Amount £60,000 (GBP)
Organisation Lancaster University 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 09/2015 
End 08/2018
 
Title 31P-NMR 
Description This method uses 31P-NMR to identify and quantify phosphorus compounds (especially organic phosphorus compounds) in soil extractions and water. We are currently developing this technique further using 2D-NMR to enable better resolution of mono-esters. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact This method provides insight into the cycling and availability of phosphorus in soils and waters. 
 
Title HPLC speciation of organic phosphorus 
Description The separation of different organic P compounds is being achieved by anion exchange chromatography. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact Cheaper assay for soil organic P forms comparing to the standard 31P-NMR method. 
 
Title Soil phosphorus mobility and resupply using diffusive gradients in thin films (DGT) 
Description A combination of DGT and DET devices and DIFS model was used to calculate the response time of solution P reequilibration, as well as the distance of depletion of solution and adsorbed P. 
Type Of Material Technology assay or reagent 
Year Produced 2014 
Provided To Others? Yes  
Impact There is ongoing research that is going to be published in scientific per reviewed journals. 
URL http://www.dgtresearch.com/
 
Title Using stable isotopes of oxygen in phosphate to trace sources of phosphorus and cycling processes 
Description Stable isotopes are often used to help understand cycling of nutrients (e.g. N and C) but phosphorus has only one stable isotope meaning this technique is not possible. However, phosphorus is nearly always associated with oxygen (phosphate) in the natural environment and oxygen does have different stable isotopes. Therefore we can use these isotopes to both trace phosphate in different systems and identify types and rates of processes occurring in soils, plants and water. 
Type Of Material Technology assay or reagent 
Year Produced 2014 
Provided To Others? Yes  
Impact The method is still very much under development, but we have used it to trace sources of phosphate in surface waters and secure funding from Natural England and the Westcountry Rivers Trust. 
 
Description Analysis of plant root exudates for the identification of co-cropping species with the potential to exploit residual soil phosphorus 
Organisation Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Country Australia, Commonwealth of 
Sector Public 
PI Contribution Growth and analysis of root exudates collected from tobacco and legume varieties.
Collaborator Contribution Partners provided the seed-lines of interest for the characterisation of root exudates and contribute to the preparation of manuscripts for publication.
Impact 1. Manuscripts prepared and/or submitted to peer-reviewed journals: CD Giles, TS George, LK Brown et al. (in review). Does the combination of citrate and phytase exudation in Nicotiana tabacum promote the acquisition of endogenous soil organic phosphorus? Plant and Soil. CD Giles, TS George, LK Brown et al. (in preparation). Depletion of soil phosphorus forms in the rhizosphere of Nicotiana tabacum plants expressing a fungal phytase: A solution 31P NMR spectroscopy study. Environ Sci Technol. CD Giles, TS George, LK Brown et al. (in preparation). Response-based selection of barley cultivars and legume species for intercropping: An assessment of root morphology and exudation in relation to phosphorus supply and nitrogen source. Plant Physiol. CD Giles, TS George, LK Brown et al. (in preparation). Complementarity and soil phosphorus acquisition by barley and legume varieties with variable root biochemical and physiological responses to phosphorus deficiency. New Phytol. 2. Presentations related to the above studies: Interactions of Soil Microorganisms and Organic Matter (ISMOM), Soil Interfaces for Sustainable Development Meeting. McGill University, Montreal, Canada. 2015 July 5 - 10. Poster presentation: 'Phosphorus transformations and mobility in the rhizosphere of phytase-exuding plants'. 9th International Symposium of the International Society of Root Research. Canberra, Australia. 2015 October 6 - 9. (1) Oral presentation: 'Complementarity and soil phosphorus acquisition by barley and legume varieties with variable root biochemical and physiological responses to phosphorus deficiency'. (2) Poster presentation: 'Complementarity in the acquisition of phosphorus among citrate and phytase exuding tobacco (Nicotiana tabacum) plants'.
Start Year 2014
 
Description Analysis of plant root exudates for the identification of co-cropping species with the potential to exploit residual soil phosphorus 
Organisation Wagga Wagga Agricultural Institute
Country Australia, Commonwealth of 
Sector Academic/University 
PI Contribution Growth and analysis of root exudates collected from tobacco and legume varieties.
Collaborator Contribution Partners provided the seed-lines of interest for the characterisation of root exudates and contribute to the preparation of manuscripts for publication.
Impact 1. Manuscripts prepared and/or submitted to peer-reviewed journals: CD Giles, TS George, LK Brown et al. (in review). Does the combination of citrate and phytase exudation in Nicotiana tabacum promote the acquisition of endogenous soil organic phosphorus? Plant and Soil. CD Giles, TS George, LK Brown et al. (in preparation). Depletion of soil phosphorus forms in the rhizosphere of Nicotiana tabacum plants expressing a fungal phytase: A solution 31P NMR spectroscopy study. Environ Sci Technol. CD Giles, TS George, LK Brown et al. (in preparation). Response-based selection of barley cultivars and legume species for intercropping: An assessment of root morphology and exudation in relation to phosphorus supply and nitrogen source. Plant Physiol. CD Giles, TS George, LK Brown et al. (in preparation). Complementarity and soil phosphorus acquisition by barley and legume varieties with variable root biochemical and physiological responses to phosphorus deficiency. New Phytol. 2. Presentations related to the above studies: Interactions of Soil Microorganisms and Organic Matter (ISMOM), Soil Interfaces for Sustainable Development Meeting. McGill University, Montreal, Canada. 2015 July 5 - 10. Poster presentation: 'Phosphorus transformations and mobility in the rhizosphere of phytase-exuding plants'. 9th International Symposium of the International Society of Root Research. Canberra, Australia. 2015 October 6 - 9. (1) Oral presentation: 'Complementarity and soil phosphorus acquisition by barley and legume varieties with variable root biochemical and physiological responses to phosphorus deficiency'. (2) Poster presentation: 'Complementarity in the acquisition of phosphorus among citrate and phytase exuding tobacco (Nicotiana tabacum) plants'.
Start Year 2014
 
Description BBSRC PARTNERSHIP AWARD FUNDING 
Organisation Smithsonian
Department Smithsonian Tropical Research Institute
Country Panama, Republic of 
Sector Public 
PI Contribution Dr Martin Blackwell and Professor Philip Haygarth from this project have successfully led and been awarded a spin off BBSRC Phosphorus Partnership Award Grant with Dr Ben Turner from the Smithsonian Tropical Research Institute in Panama.
Collaborator Contribution Dr Ben Turner and his team first visited us in October 2014 and further collaborations, papers, grant funding and technician swapping and visits are planned for 2015 and beyond.
Impact The funding is worth £20k and will result in exchange of information, publications and possible grant applications, It is in an early phase.
Start Year 2014
 
Description Effect of low molecular weight organic acids on soil P mobility and resupply from solid phase. 
Organisation Institute of Agribusiness
Country Chile, Republic of 
Sector Academic/University 
PI Contribution Soil analysis and knowledge in soil organic P. Events, talks and student training.
Collaborator Contribution Soil analysis during a PhD student internship for 3 months in LEC, Lancaster University.
Impact A manuscript was published on Environmental Science & Technology journal with the main findings of the research performed.
Start Year 2015
 
Description Effect of soybean/brachiaria grass rotation on soil P mobility, availability and speciation. 
Organisation Sao Paulo State University
Country Brazil, Federative Republic of 
Sector Academic/University 
PI Contribution Soil analysis and knowledge in soil organic P, and student training. The PhD student Danilo Almeida is currently visiting our labs (one year stay ending on July 2017) funded bu Sao Paulo State Research Council (FAPESP- BRAZIL).
Collaborator Contribution Soil analysis performed by PhD students during internship.
Impact One publication submitted to Plant and Soil Journal.
Start Year 2016
 
Description Phosphorus nano-particle analysis 
Organisation Helmholtz Association of German Research Centres
Department Forschungszentrum Jülich GmbH
Country Germany, Federal Republic of 
Sector Public 
PI Contribution Soil analysis and knowledge in soil organic P. Events and talks.
Collaborator Contribution Soil analysis and knowledge in soil P. Postdoc scientific stay.
Impact No output yet
Start Year 2015
 
Description Soil organic P speciation 
Organisation Smithsonian
Department Smithsonian Tropical Research Institute
Country Panama, Republic of 
Sector Public 
PI Contribution Soil analysis and knowledge in soil organic P. Events, talks and student training. The OPUS postdoc spent a month on STRI - Panama performing organic P analysis in cooperation with Dr. Benjamin Turner.
Collaborator Contribution Soil analysis and knowledge in soil organic P. Events, talks and student training.
Impact Joint publications and student exchange for training and performing experiments.
Start Year 2014
 
Description OP2016 - Organic Phosphorus Workshop 2016: Organic Phosphorus in the Environment: Solutions for Phosphorus Security 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact OP2016 - Organic Phosphorus Workshop 2016: Organic Phosphorus in the Environment: Solutions for Phosphorus Security #organicP2016
The Organic P Workshop was held in the lake District (UK) from 5 to 9th of September 2016. Please our draft website for a detailed information about the workshop and its outputs (http://op2016.com/).
Year(s) Of Engagement Activity 2016
URL http://op2016.com/
 
Description Biology Experience Day for local schools at Lancaster University 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact 80 pupils (year 12 Biology Students) came to LEC and each group of approximately 10 students received a 10 minute 'hands-on' demonstration on our research on ' Diffuse Pollution in Agriculture' and one on 'Nutrient Cycling in ecosystems'.

Feedback from students and teachers was very positive, showing that the year 12 Biology Students were deeply inspired by the research activities developed in LEC.
Year(s) Of Engagement Activity 2014
URL http://www.lancaster.ac.uk/lec/about-us/supporting-schools-and-community/biology-experience-days/
 
Description Co-Convener of EGU session BG1.7/SSS5.16 Interdisciplinary session on the global Phosphorus cycle (Vienna, Austria). 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Phosphorus (P) is an essential element for life on Earth and is tightly cycled within the biosphere. Throughout geological history, P availability has regulated biological productivity with impacts on the global carbon cycle. Today, human activities are significantly changing the natural cycling of P. Phosphate mining has depleted geological P reserves, while increased inputs of P to terrestrial ecosystems have enhanced fluxes of P to lakes and the oceans.

Direct anthropogenic perturbations of the P cycle, coupled with other human-induced stresses, have impacted numerous environments. Forest ecosystems may be losing their ability to recycle P efficiently, due to excessive N input, extensive biomass removal, and climatic stress. Soils, which serve as the biogeochemical fulcrum of the terrestrial P cycle, have been greatly altered by fertilizer use in recent decades. Changes in the P cycle on land impact on the magnitude and timing of P fluxes into aquatic ecosystems, influencing their trophic state. Burial in sediments returns P to the geological sink, eventually forming economically viable P deposits. Throughout the P cycle, redox conditions play a key role in transformations and mobility of P.

This interdisciplinary session invites contributions to the study of P from across the geosciences, and aims to foster links between researchers working on different aspects of the P cycle. We target a balanced session giving equal weight across the continuum of environments in the P cycle, from forests, soils and groundwater, through lakes, rivers and estuaries, to oceans, marine sediments and geological P deposits. We welcome studies of both past and present P cycling, with a focus on novel techniques and approaches.
Year(s) Of Engagement Activity 2016
URL http://meetingorganizer.copernicus.org/EGU2016/session/21891
 
Description Co-Convener of EGU session BG1.9/SSS13.11 - Interdisciplinary session on the global Phosphorus cycle (Vienna, Austria) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact BG1.9/SSS13.11
Interdisciplinary session on the global Phosphorus cycle (co-organized)PICO session

Convener: Tom Jilbert
Co-Conveners: Phil Haygarth , Daniel Blackburn , Ben Surridge , Federica Tamburini , Christian März , Tobias Goldhammer , Friederike Lang , Jaane Krüger
PICO / Fri, 28 Apr, 08:30-10:00 / PICO spot 5a
Add Session to your Personal Programme Add this session to your Personal programme

Phosphorus (P) is an essential element for life on Earth and is tightly cycled within the biosphere. Throughout geological history, P availability has regulated biological productivity with impacts on the global carbon cycle. Today, human activities are significantly changing the natural cycling of P. Phosphate mining has depleted geological P reserves, while increased inputs of P to terrestrial ecosystems have enhanced fluxes of P to lakes and the oceans.

Direct anthropogenic perturbations of the P cycle, coupled with other human-induced stresses, have impacted numerous environments. Forest ecosystems may be losing their ability to recycle P efficiently, due to excessive N input, extensive biomass removal, and climatic stress. Soils, which serve as the biogeochemical fulcrum of the terrestrial P cycle, have been greatly altered by fertilizer use in recent decades. Changes in the P cycle on land impact on the magnitude and timing of P fluxes into aquatic ecosystems, influencing their trophic state. Burial in sediments returns P to the geological sink, eventually forming economically viable P deposits. Throughout the P cycle, redox conditions play a key role in transformations and mobility of P.

This interdisciplinary session invites contributions to the study of P from across the geosciences, and aims to foster links between researchers working on different aspects of the P cycle. We target a balanced session giving equal weight across the continuum of environments in the P cycle, from forests, soils and groundwater, through lakes, rivers and estuaries, to oceans, marine sediments and geological P deposits. We welcome studies of both past and present P cycling, with a focus on novel techniques and approaches.

Keynote: Sonya Dyhrman, Lamont-Doherty Earth Observatory, Columbia University
Year(s) Of Engagement Activity 2017
URL http://meetingorganizer.copernicus.org/EGU2017/session/24918
 
Description Co-Convener of EGU session SSS4.20/IG25 Insights into phosphorus biogeochemistry through soil systems (Vienna, Austria) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Phosphorus (P) is an essential element for all life and, under ambient conditions, is tightly cycled within the biosphere. However, human action has significantly altered the natural P cycle. Phosphate mining has depleted geological P reserves, while increased inputs of P to terrestrial ecosystems have enhanced fluxes of P to lakes and the oceans. On land, the soil system is a biogeochemical fulcrum, responding to the perturbed P cycle and ultimately determining the magnitude and timing of inorganic and organic P fluxes between terrestrial and aquatic ecosystems. Meanwhile in freshwater and marine aquatic environments, P inputs determine the trophic state of the ecosystem, while burial in sediments returns P to the geological sink. Throughout the P cycle, redox conditions play a key role in transformations and mobility of P.

This session investigates the P cycle in soil and aquatic systems across a range of scales. Contributions include:

• studies of soils and sediments on the pore and ped scales, including the application of novel techniques to study P
• investigations of the redox chemistry of P in natural systems
• meta-analyses of input-cycling-export of P from soils at multiple scales
• phosphorus cycling in coastal seas, including its role in coastal eutrophication and burial in marine sediments
• global P cycling on geological timescales
Year(s) Of Engagement Activity 2015
URL http://meetingorganizer.copernicus.org/EGU2015/session/17461
 
Description Geography Experience Day for local schools at Lancaster University 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact 60 pupils (Year 12) attended for an Experience Day. Groups of 30 attended a 90 minute laboratory workshop investigating runoff, sediment and nutrient loss from soil boxes with different 'land use', with associated examples of ecological diversity from each 'land use' type
Year(s) Of Engagement Activity 2015
URL http://www.lancaster.ac.uk/lec/about-us/supporting-schools-and-community/
 
Description On farm nutrient efficiencies invited talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact A talk given to the UK Nutrient Platform Biorefine meeting at Royal Society of Edinburgh, Sept 2015.
Year(s) Of Engagement Activity 2015
URL http://link2energy.co.uk/uk-nutrient-platform-september-2015
 
Description Organic Phosphorus Workshop 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This was an international conference on organic phosphorus with ca. 120 delegates.
Year(s) Of Engagement Activity 2016
URL https://op2016.com/
 
Description Organization of Organic Phosphorus Workshop Lake District, England 5th - 9th September 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Following on from the successful meeting held in Panama in 2013, we are delighted to announce a follow-on workshop for soil, water, plant and environmental scientists to come together to study and share ideas and innovation on the subject of "Organic Phosphorus in the Environment: Solutions for Phosphorus Security".
All academics and students involved in organic phosphorus research are welcome to join us on this constructive workshop, aimed at integrating, learning and planning collaborative frontier science that will help address the main challenges in this field. Understanding and quantifying the relative importance of organic phosphorus in the global phosphorus cycle requires exploration on multiple research fronts. Aspects such as speciation methods, ecological stoichiometry, bioavailability, abiotic stabilization, transfers from terrestrial into aquatic ecosystems, chemical lability and mobility, trophic interactions, microbial ecology and biochemistry of the degradation of specific compounds are some of the areas covered in this event.
This 'Monday lunch - Friday lunch' event will be arranged as a workshop, with everyone working together in teams towards a common goal and consensus. During the conference all delegates will be challenged to come up with new questions and needs for organic phosphorus research, which will ultimately be published in: (1) a single, multi authored consensus paper on the state of the art in a high profile journal, and; (2) the opportunity for offered refereed papers to be published in Plant and Soil special issue. In addition to these collaborative activities and the inspiration from the beautiful landscape of the Lake District, the Workshop will also involve keynote addresses, oral and poster presentations and break-out group discussions. Exciting opportunities for social and outside activities will also be available.
Year(s) Of Engagement Activity 2015,2016
URL http://op2016.com/
 
Description Soil Phosphorus Forum 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Soil phosphorus forum is an open space of scientific discussion about soil phosphorus research. This site has had over 200 posts published and 4.3k visits in 2016, over 3k visits on 2015 and 1k visits in 2014 when it was launched.

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Year(s) Of Engagement Activity 2014,2015,2016
URL http://soilpforum.com/
 
Description Soil Phosphorus talks at Forschungszentrum Jülich (Jülich, Germany) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Working group on establishing a collaboration for future projects and student and postdocs scientific stay. Talks given on soil phosphorus transfer and soil phosphorus mobility and bioavalability.
Year(s) Of Engagement Activity 2015
 
Description Talk given to Danish Agronomists 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk on managing nutrients in catchments was given to a group of visiting Danish agronomists in Dundee, Oct 2015
Year(s) Of Engagement Activity 2015
 
Description YouTube Channel OP2016 - Organic Phosphorus Workshop - 5th - 9th September 2016, Lake District, England Organic Phosphorus in the Environment: Solutions for Phosphorus Security https://op2016.com/ 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact 20 videos uploaded from talks held on the OP2016 - Organic Phosphorus Workshop, over 1500 views (>80h watch time).
Year(s) Of Engagement Activity 2016,2017
URL https://www.youtube.com/channel/UCtGI3eUZscCgByewafsQKdw/videos?sort=dd&shelf_id=0&view=0