Mechanisms to improve integrative research at the science-policy interface for sustainable catchment management

Greater integration between researchers and policy makers is required to provide an evidence base that is transparent, integrated, and adaptive to support the complexities of sustainable catchment management. Opening-up and closing-down mechanisms are equally important in creating and establishing such an evidence base. We provide examples of both types based on our recent research and knowledge-transfer activities at the science-policy interface. Through our coordination role for the United Kingdom government we provide opening up physical and virtual forums for researchers and government science and policy staff to learn about and assess the gaps and uncertainties of the evidence base. Closing-down mechanisms are vital to policy cycles, in that they distil what is known and what is unknown. The Diffuse Pollution User Manual provides a valuable tool for policy and catchment management staff to assess the potential effectiveness of different combinations of remedial diffuse-pollution mitigation methods. It is vital that that opening-up and closing-down mechanisms are iteratively linked given the complexity and uncertainty of the science and policy cycles. Advances in integrative research at the science-policy interface are vital if there is to be a move to more deliberative policy making

Changes in bicarbonate-extractable inorganic and organic phosphorus by drying pasture soils

Soils are commonly dried in the laboratory prior to the determination of P fractions, but this can profoundly influence the results. We investigated the impact of soil drying on bicarbonate-extractable inorganic and organic P in 29 permanent lowland pasture soils from England and Wales (total C 29-80 g C kg -1 soil, day 219-681 g kg-1 soil, pH 4.4-6.8) by extracting soils at approximate field moisture capacity and after air-drying at 30°C for 7 d. Air-drying increased the mean bicarbonate-extractable inorganic P from 14.8 to 22.5 mg P kg-1 soil, and the mean bicarbonate-extractable organic P from 17.4 to 25.7 mg P kg-' soil. Proportional increases for individual soils following drying were between 11 and 165% for inorganic P, and between -2 and 137% for organic P, being greatest in soils with low P concentrations. The results are unlikely to influence tests for plant-available P, because these are derived from analyses of air-dried samples, but have important implications for attempts to relate bicarbonate-extractable P fractions to processes operating under field conditions

Potential contribution of lysed bacterial cells to phosphorus solubilisation in two rewetted Australian pasture soils

Soil drying renders considerable amounts of phosphorus soluble upon rewetting, which may be partly derived from lysed microbial cells. Using direct bacterial cell counting in water and tetra-sodium pyrophosphate extracts of two Australian pasture soils, we found that almost all extractable cells were lysed following the rewetting of dry soils. The amounts of phosphorus in the lysed cells corresponded closely to the increases in water-extractable phosphorus following soil drying, suggesting that bacterial cell lysis is a major source of the released phosphorus

Can policy be risk-based? The cultural theory of risk and the case of livestock disease containment

This article explores the nature of calls for risk-based policy present in expert discourse from a cultural theory perspective. Semi-structured interviews with professionals engaged in the research and management of livestock disease control provide the data for a reading proposing that the real basis of policy relating to socio-technical hazards is deeply political and cannot be purified through ‘escape routes’ to objectivity. Scientists and risk managers are shown calling, on the one hand, for risk-based policy approaches while on the other acknowledging a range of policy drivers outside the scope of conventional quantitative risk analysis including group interests, eventualities such as outbreaks, historical antecedents, emergent scientific advances and other contingencies. Calls for risk-based policy are presented, following cultural theory, as ideals connected to a reductionist epistemology and serving particular professional interests over others rather than as realistic proposals for a paradigm shift

The riparian reactive interface: a climate-sensitive gatekeeper of global nutrient cycles

Riparian zones are critical interfaces to freshwater systems, acting as gateways for the conveyance and modification of macronutrient fluxes from land to rivers and oceans. In this paper, we propose that certain riparian conditions and processes (conceptually 'Riparian Reactive Interfaces') may be susceptible to environmental change with consequences of accelerating local nutrient cycling cascading to global impacts on the cycles of carbon (C), nitrogen (N), and phosphorus (P). However, we argue that this concept is insufficiently understood and that research has not yet established robust baseline data to predict and measure change at the key riparian ecosystem interface. We suggest one contributing factor as lack of interdisciplinary study of abiotic and biotic processes linking C, N, and P dynamics and another being emphasis on riparian ecology and restoration that limits frameworks for handling and scaling topography-soil-water-climate physical and biogeochemical observations from plot to large catchment scales. Scientific effort is required now to evaluate riparian current and future controls on global nutrient cycles through multi-nutrient (and controlling element) studies, grounded in landscape frameworks for dynamic riparian behaviour variation, facilitating scaling to catchment predictions

A method-centric 'User Manual' for the mitigation of diffuse water pollution from agriculture

We describe the development of a manual of methods for mitigating diffuse water pollution from agriculture and its important influence on policy and practice in England and Wales. The objective of the ‘User Manual’ was to provide policy makers and those implementing policies with information about the cost, effectiveness and applicability of potential methods in a form that would be readily understood by non-specialists. The ‘User Manual’ was based on earlier reports synthesizing available research data and, where data were unavailable, used expert elicitation. The outcome generated 44 potential methods (under the broad categories of land use, soil management, livestock management, fertilizer management, manure management and farm infrastructure) and described the simultaneous impact of applying each method on losses of nitrate, phosphorus and faecal indicator organisms relative to baseline losses. Estimates of cost and effectiveness were presented at the whole-farm level for seven model farm types. Methods differed widely in their cost-effectiveness and applicability to the different model farms. Advantages and limitations of the approach are discussed and subsequent developments of the original ‘User Manual’ are described, together with the opinions of catchment officers who have used the ‘User Manual’ to implement mitigation methods on farms

A novel grass hybrid to reduce flood generation in temperate regions

We report on the evaluation of a novel grass hybrid that provides efficient forage production and could help mitigate flooding. Perennial ryegrass (Lolium perenne) is the grass species of choice for most farmers, but lacks resilience against extremes of climate. We hybridised L. perenne onto a closely related and more stress-resistant grass species, meadow fescue Festuca pratensis. We demonstrate that the L. perenne × F. pratensis cultivar can reduce runoff during the events by 51% compared to a leading UK nationally recommended L. perenne cultivar and by 43% compared to F. pratensis over a two year field experiment. We present evidence that the reduced runoff from this Festulolium cultivar was due to intense initial root growth followed by rapid senescence, especially at depth. Hybrid grasses of this type show potential for reducing the likelihood of flooding, whilst providing food production under conditions of changing climate

High-resolution monitoring of catchment nutrient response to the end of the 2011-2012 drought in England, captured by the demonstration test catchments.

The Demonstration Test Catchments (DTC) project is a UK Government funded initiative to test the effectiveness of on-farm mitigation measures designed to reduce agricultural pollution without compromising farm productivity. Three distinct catchments in England have been chosen to test the efficacy of mitigation measures on working farms in small tributary sub-catchments equipped with continuous water quality monitoring stations. The Hampshire Avon in the south is a mixed livestock and arable farming catchment, the River Wensum in the east is a lowland catchment with predominantly arable farming and land use in the River Eden catchment in the north-west is predominantly livestock farming. One of the many strengths of the DTC as a national research platform is that it provides the ability to investigate catchment hydrology and biogeochemical response across different landscapes and geoclimatic characteristics, with a range of differing flow behaviours, geochemistries and nutrient chemistries. Although numerous authors present studies of individual catchment responses to storms, no studies exist of multiple catchment responses to the same rainfall event captured with in situ high-resolution nutrient monitoring at a national scale. This paper brings together findings from all three DTC research groups to compare the response of the catchments to a major storm event in April 2012. This was one of the first weather fronts to track across the country following a prolonged drought period affecting much of the UK through 2011–2012, marking an unusual meteorological transition when a rapid shift from drought to flood risk occurred. The effects of the weather front on discharge and water chemistry parameters, including nitrogen species (NO3-N and NH4-N) and phosphorus fractions (total P (TP) and total reactive P (TRP)), measured at a half-hourly time step are examined. When considered in the context of one hydrological year, flow and concentration duration curves reveal that the weather fronts resulted in extreme flow, nitrate and TP concentrations in all three catchments but with distinct differences in both hydrographs and chemographs. Hysteresis loops constructed from high resolution data are used to highlight an array of potential pollutant sources and delivery pathways. In the Hampshire Avon DTC, transport was dominated by sub-surface processes, where phosphorus, largely in the soluble form, was found to be transport-limited. In the Wensum DTC, transport was largely dominated by rapid sub-surface movement due to the presence of under-drainage, which mobilised large quantities of nitrate during the storm. In the Eden DTC, transport was found to be initially dominated by surface runoff, which switched to subsurface delivery on the falling limb of the hydrograph, with the surface delivery transporting large amounts of particulate phosphorus to the river, with a transport-limited response. The lack of exhaustion of nutrient delivery in response to such extreme flow generation indicates the size of the nutrient pools stored in these catchments, and highlights the scale of the challenges faced by environmental managers when designing mitigation measures to reduce the flux of nutrients to UK river systems from diffuse agricultural sources

Impacts of Climate Change on indirect human exposure to pathogens and chemicals from agriculture

Objective: Climate change is likely to affect the nature of pathogens and chemicals in the environment and their fate and transport. Future risks of pathogens and chemicals could therefore be very different from those of today. In this review, we assess the implications of climate change for changes in human exposures to pathogens and chemicals in agricultural systems in the United Kingdom and discuss the subsequent effects on health impacts. Data sources: In this review, we used expert input and considered literature on climate change ; health effects resulting from exposure to pathogens and chemicals arising from agriculture ; inputs of chemicals and pathogens to agricultural systems ; and human exposure pathways for pathogens and chemicals in agricultural systems. Data synthesis: We established the current evidence base for health effects of chemicals and pathogens in the agricultural environment ; determined the potential implications of climate change on chemical and pathogen inputs in agricultural systems ; and explored the effects of climate change on environmental transport and fate of different contaminant types. We combined these data to assess the implications of climate change in terms of indirect human exposure to pathogens and chemicals in agricultural systems. We then developed recommendations on future research and policy changes to manage any adverse increases in risks. Conclusions: Overall, climate change is likely to increase human exposures to agricultural contaminants. The magnitude of the increases will be highly dependent on the contaminant type. Risks from many pathogens and particulate and particle-associated contaminants could increase significantly. These increases in exposure can, however, be managed for the most part through targeted research and policy changes

Guiding phosphorus stewardship for multiple ecosystem services

The essential role of phosphorus (P) for agriculture and its impact on water quality has received decades of research attention. However, the benefits of sustainable P use and management for society due to its downstream impacts on multiple ecosystem services are rarely acknowledged. We propose a conceptual framework—the “phosphorus-ecosystem services cascade” (PESC)—to integrate the key ecosystem processes and functions that moderate the relationship between P released to the environment from human actions and ecosystem services at distinct spatial and temporal scales. Indirect pathways in the cascade via soil and aquatic processes link anthropogenic P to biodiversity and multiple services, including recreation, drinking water provision, and fisheries. As anthropogenic P cascades through catchments, it often shifts from a subsidy to a stressor of ecosystem services. Phosphorus stewardship can have emergent ecosystem service co-benefits due to synergies with other societal or management goals (e.g., recycling of livestock manures and organic wastes could impact soil carbon storage). Applying the PESC framework, we identify key research priorities to align P stewardship with the management of multiple ecosystem services, such as incorporating additional services into agri-environmental P indices, assessing how widespread recycling of organic P sources could differentially impact agricultural yields and water quality, and accounting for shifting baselines in P stewardship due to climate change. Ultimately, P impacts depend on site-specific agricultural and biogeophysical contexts, so greater precision in targeting stewardship strategies to specific locations would help to optimize for ecosystem services and to more effectively internalize the downstream costs of farm nutrient management