Major agricultural changes required to mitigate phosphorus losses under climate change

Ockenden, Mary; Hollaway, Michael; Beven, Keith; Collins, Adrian L.; Evans, R.; Falloon, Pete; Forber, Kirsty J.; Hiscock, Kevin M.; Kahana, Ron; Macleod, Christopher; Tych, Włodek; Villamizar, Martha L.; Wearing, Catherine; Withers, P. J. A.; Zhou, Jian Guo; Barker, Philip A.; Burke, Sean; Freer, J. E.; Johnes, Penny J; Snell, M. A.; Surridge, Ben; Haygarth, P. M.

doi:10.1038/s41467-017-00232-0

Cited by 146 publications

(111 citation statements)

References 41 publications

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“…A growing body of evidence shows that the efforts in combating eutrophication in North America and Europe (Bol et al, 2018; Jarvie et al, 2013), and specifically of the Baltic Sea (Conley et al, 2009; European Court of Auditors, 2016), are unsatisfactory. A greater use of mitigation measures is thus required to achieve good chemical and ecological status, particularly in light of climate change (Ockenden et al, 2017). However, many studies show mixed effectiveness of these measures on water quality and considerable lags between treatment and response (Dodd and Sharpley, 2015; Meals et al, 2010) that are increasingly difficult to communicate to stakeholders expecting instant improvements.…”

Section: Discussionmentioning

confidence: 99%

“…Mitigation measures are often built in headwater catchments, which control the water quality signature of the stream network (Abbott et al, 2018; Alexander et al, 2007) and are hot spots of agricultural water pollution (Bieroza et al, 2018). Recent studies indicate that extreme weather can exacerbate nutrient and sediment export from agricultural headwater catchments (Mellander et al, 2018), requiring large‐scale mitigation solutions to offset the increased hydrologic flashiness of the changing climate (Ockenden et al, 2017). …”

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confidence: 99%

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Hydrologic Extremes and Legacy Sources Can Override Efforts to Mitigate Nutrient and Sediment Losses at the Catchment Scale

et al. 2019

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Combating eutrophication requires changes in land and water management in agricultural catchments and implementation of mitigation measures to reduce phosphorus (P), nitrogen (N) and suspended sediment (SS) losses. To date, such mitigation measures have been built in many agricultural catchments, but there is a lack of studies evaluating their effectiveness. Here we evaluated the effectiveness of mitigation measures in a clay soil‐dominated headwater catchment by combining the evaluation of long‐term and high‐frequency data with punctual measurements upstream and downstream of three mitigation measures: lime‐filter drains, a two‐stage ditch, and a sedimentation pond. Long‐term hydrochemical data at the catchment outlet showed a significant decrease in P (−15%) and SS (−28%) and an increase in nitrate nitrogen (NO3–N, +13%) concentrations. High‐frequency (hourly) measurements with a wet‐chemistry analyzer (total and reactive P) and optical sensor (NO3–N and SS) showed that the catchment is an abundant source of nutrients and sediments and that their transport is exacerbated by prolonged drought and resuspension of stream sediments during storm events. Lime‐filter drains showed a decrease in SS by 76% and total P by 80% and an increase in NO3–N by 45% compared with traditional drains, potentially indicating pollution swapping. The effectiveness of two‐stage ditch and sedimentation pond was less evident and depended on the prevalent hydrometeorological conditions that drove the resuspension of bed sediments and associated sediment‐bound P transport. These results suggest that increased frequency of prolonged drought due to changing weather patterns and resuspension of SS and sediment‐bound P during storm events can override the generally positive effect of mitigation measures. Core Ideas We assessed the efficiency of catchment mitigation measures to reduce water pollution. At the catchment outlet, concentrations of P and sediments decreased by 15 and 28%. Lime‐filter drains reduced P and sediments by 80% but increased nitrate by 45%. Prolonged drought and resuspension of sediments exacerbated stream nutrient export. High‐frequency data show that legacy sources can override mitigation efforts.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Hydrologic Extremes and Legacy Sources Can Override Efforts to Mitigate Nutrient and Sediment Losses at the Catchment Scale

et al. 2019

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“…Both agronomic and environmental P management decisions are highly site specific, which makes them variably cost effective and, in the case of environmental decisions, liable to failure, such as during extreme rainfall events (Howden et al, 2007; Nelson et al, 2009; Ockenden et al, 2017). For this reason, Mellander et al (2018) recommends the development of integrated climate–chemical watershed response indicators for water quality objectives.…”

Section: Our Directions For the Future Development Of Decision Supportmentioning

confidence: 99%

A Global Perspective on Phosphorus Management Decision Support in Agriculture: Lessons Learned and Future Directions

et al. 2019

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The evolution of phosphorus (P) management decision support tools (DSTs) and systems (DSS), in support of food and environmental security has been most strongly affected in developed regions by national strategies (i) to optimize levels of plant available P in agricultural soils, and (ii) to mitigate P runoff to water bodies. In the United States, Western Europe, and New Zealand, combinations of regulatory and voluntary strategies, sometimes backed by economic incentives, have often been driven by reactive legislation to protect water bodies. Farmer‐specific DSSs, either based on modeling of P transfer source and transport mechanisms, or when coupled with farm‐specific information or local knowledge, have typically guided best practices, education, and implementation, yet applying DSSs in data poor catchments and/or where user adoption is poor hampers the effectiveness of these systems. Recent developments focused on integrated digital mapping of hydrologically sensitive areas and critical source areas, sometimes using real‐time data and weather forecasting, have rapidly advanced runoff modeling and education. Advances in technology related to monitoring, imaging, sensors, remote sensing, and analytical instrumentation will facilitate the development of DSSs that can predict heterogeneity over wider geographical areas. However, significant challenges remain in developing DSSs that incorporate “big data” in a format that is acceptable to users, and that adequately accounts for catchment variability, farming systems, and farmer behavior. Future efforts will undoubtedly focus on improving efficiency and conserving phosphate rock reserves in the face of future scarcity or prohibitive cost. Most importantly, the principles reviewed here are critical for sustainable agriculture. Core Ideas Strategies protecting water bodies are often driven by reactive legislation. Phosphorus management focuses on plant available P and mitigating P runoff. Decision support is based on P transfer, best practices, education, and action. Recent scientific developments have rapidly advanced runoff modeling and education. DS challenges are “big data,” farming systems, and farmer behavior.

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“…Continuous-time and discrete-time model structures are described below (from Ockenden et al, 2017). The parameter estimates in both continuous-time models and discrete-time models are formulaically related (Table S3).…”

Section: Transfer Function Model Identificationmentioning

confidence: 99%

Prediction of storm transfers and annual loads with data-based mechanistic models using high-frequency data

Ockenden

Tych

Beven

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Excess nutrients in surface waters, such as phosphorus (P) from agriculture, result in poor water quality, with adverse effects on ecological health and costs for remediation. However, understanding and prediction of P transfers in catchments have been limited by inadequate data and over-parameterised models with high uncertainty. We show that, with high temporal resolution data, we are able to identify simple dynamic models that capture the P load dynamics in three contrasting agricultural catchments in the UK. For a flashy catchment, a linear, second-order (two pathways) model for discharge gave high simulation efficiencies for short-term storm sequences and was useful in highlighting uncertainties in out-of-bank flows. A model with nonlinear rainfall input was appropriate for predicting seasonal or annual cumulative P loads where antecedent conditions affected the catchment response. For second-order models, the time constant for the fast pathway varied between 2 and 15 h for all three catchments and for both discharge and P, confirming that high temporal resolution data are necessary to capture the dynamic responses in small catchments (10-50 km 2 ). The models led to a better understanding of the dominant nutrient transfer modes, which will be helpful in determining phosphorus transfers following changes in precipitation patterns in the future.

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Major agricultural changes required to mitigate phosphorus losses under climate change

Cited by 146 publications

References 41 publications

Hydrologic Extremes and Legacy Sources Can Override Efforts to Mitigate Nutrient and Sediment Losses at the Catchment Scale

Hydrologic Extremes and Legacy Sources Can Override Efforts to Mitigate Nutrient and Sediment Losses at the Catchment Scale

A Global Perspective on Phosphorus Management Decision Support in Agriculture: Lessons Learned and Future Directions

Prediction of storm transfers and annual loads with data-based mechanistic models using high-frequency data

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