Improving the sustainability of phosphorus use in arable farming

The increasing global demand for food, concerns over dwindling reserves of good quality phosphate rock and the climate-change impacts of fertiliser manufacture, fluctuating fertiliser prices, and the adverse environmental, social and economic consequences of phosphorus (P) pollution of water require the development of innovative and more sustainable solutions to the use and management of P on farms. Current systems of production rely on inputs of highly water-soluble fertilisers to maintain large reserves of background P in the soil. Recovery of applied P by crops is consequently low (<30%) and this inefficiency is not only wasteful of resources but also increases the risk of eutrophication through increased P loss in runoff from land. A peak in global phosphate rock production could occur within the next two decades whilst eutrophication is estimated to be costing the UK over £75 million per annum. A potential alternative and more sustainable strategy for P use in arable farming systems is to maintain a lower background of soil P but supplement this with more targeted P applications and/or by fertilisers that are more efficiently used, and/or fertilisers recovered from domestic or livestock wastewaters. We propose here that adoption of these more sustainable P use strategies will reduce growing costs and current dependence on elevated soil P-fertility, so will help to preserve finite global reserves of P and reduce export of P in runoff from land. In this proposal a multi-disciplinary, cross-industry research team will investigate and develop a new direction for P management that will improve P-use efficiency in arable crops, maximise recycling of wastewater P, reduce the pressure on rock phosphate reserves and minimise wider environmental impacts. Through multi-centre modelling, laboratory studies and field experiments we will compare and develop methods to improve P-use efficiency by (a) reducing the fixation of applied P by soils, (b) improving the accessibility of applied P to crops, and (c) improving the exploitation of soil P previously considered to be largely unavailable to crops. The magnitude of the economic and wider environmental benefits from maintaining lower soil P-fertility need to be quantified across a range of soil types and cropping systems. On completion, the project will deliver novel and profitable soil and fertiliser management strategies that will help farmers maintain the economic viability of their farm businesses and meet any future restrictions on P management under the Water Framework Directive. The project will have relevance across the spectrum of conventional, LEAF and organic farming systems and will involve overseas collaboration on what is internationally recognised as a key issue for sustainable farming and global food security. BBSRC funded project will develop mathematical models and optimisation techniques to describe phosphate movement and uptake by cropping systems.

There are two main objectives for the entire Defra LINK project. (1) To develop novel targeted fertiliser technologies and soil-P acquisition strategies that will enable arable crops to be grown on soils having a lower P status without sacrificing crop yield, crop quality or farm profits; (2) To determine whether adoption of novel soil and fertiliser strategies on low-P soils will enable reduction in P inputs, reduce emissions of P from land to water and lessen the wider negative environmental impacts of arable farming. Summary of the modelling project funded by BBSRC Within this project we will develop a new generation mathematical models that (a) simultaneously predict the combined crop (e.g. rooting pattern) and soil (e.g. diffusion coefficients) traits required for efficient utilization of P in low P soils (b) quantify the rates and partitioning of P uptake between root and shoot under different fertiliser application strategies (c) predict optimum fertiliser application strategies (timing, zone of application) for maximising efficiency of P use for different soil/crop combinations. We achieve this via systematically completing the following tasks Task 1 Validating and linking soil and single root models Task 2 Development of root system and crop scale models Task 3 Scenario analysis for optimizing P fertilization strategies.

This project is part of the large Defra LINK project titled 'Improving the phosphorus use in arable farming'. On completion, the Defra LINK project will deliver novel and profitable soil and fertiliser management strategies that will help farmers maintain the economic viability of their farm businesses and meet any future restrictions on P management under the Water Framework Directive. The project will have relevance across the spectrum of conventional, LEAF and organic farming systems and will involve overseas collaboration on what is internationally recognised as a key issue for sustainable farming and global food security. The BBSRC funded part of the Defra LINK project will deal with mathematical modelling of P uptake by plants in order to optimise the fertilise placement and minimize the runoff. The modelling will enable to interpret and translate data across the spatial scales and thereby increase the value of experimental findings. By design, the project is directly linked to industry and contains a range of stakeholders from fertiliser producers through to agronomic extension officers. These industrial sponsors form key partners in the project and consequently they will be invited to attend all the project workshops. They will also be integrally involved in the project co-ordination meetings in which the experimental designs are decided upon thereby ensuring the real world relevance of the science. Many of the industrial academic stakeholders also actively engaged in advising on land use policy in the UK (e.g. via DEFRA, Welsh Assembly Government etc). Academic benefits arising from this work will be many fold. The most direct academic beneficiaries will be the crop science community (academic and industrial). The models developed will allow them to integrate their findings in a quantitative manner and determine how different sub-systems in plants interact. Other beneficiaries will include researchers involved in bioremediation and pollution control research since plants often act as a first point of contact for pollutant movement. The work also has potential in predicting the fate and transport of human pathogens (e.g. E. coli O157) in agricultural systems. Specifically, it will allow scaling up from pathogen behaviour at the rhizosphere level to the field level, a key research challenge which has not yet been achieved. In addition, there will be beneficiaries in the biomedical and mathematical modelling and engineering communities since plant roots are in the modelling sense 'similar' to human vascular and lymphatic system, and lung. A key International priority is to breed crops for changing climate conditions, in particular for conditions of severe drought (Africa, Asia etc), but also for areas of severe flooding (Asia, Europe etc). Our research will directly benefit crop breeders in guiding which plant root system traits are important for any soil moisture conditions. Similarly, waterlogging is another major limitation to crop production which will be aided by the creation of generic modelling platforms which can be adapted to help address mitigation options. Agricultural and environmental policy makers concerned with the fate of pollutants and fertilizers in the environment will also benefit from this research. At a wider scale we anticipate benefits for the international development community who can use the results of our research to produce policy recommendations for areas likely to undergo significant environmental climate change, again with respect to the appropriate management of soil. In addition, they have the potential to be used for risk assessment purposes and would provide mechanistic detail to existing Environment Agency models.