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The phosphorus cycle in n orthwest European agricultural soils

Understand the impact of phosphorus on water ecology in Northwest Europe, focusing on soil and crop health. Explore application standards to manage soil phosphorus levels for sustainable agricultural practices. Assess P loss and yield to achieve equilibrium fertilization. Discover strategies to reach target zones for optimal crop yield and minimal soil phosphorus losses.

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The phosphorus cycle in n orthwest European agricultural soils

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  1. The phosphorus cycle in northwest European agricultural soils Fien Amery Bart Vandecasteele Nutrihort September 17, 2013 Institute for Agricultural and Fisheries Research Plant Sciences Unit www.ilvo.vlaanderen.be Agriculture and Fisheries Policy Area

  2. Phosphorus in water and soil • Phosphorus (P): negativeeffectson water ecology (eutrophication) • → Water FrameworkDirective • → NitrateDirective • Target: agricultural P application • Good, but… • Impact onsoil and crops? • Efficient tool? • DifferencesamongMemberStates? • Literaturestudy

  3. Phosphorus in surface waters • Goal: goodecological status/potential of water bodies Water FrameworkDirective • Eachmember state: • Defineecologicalreferencecondition and classificationsforeachsurface water type • Relateecologyto chemical/physicalconditions(P concentration) • P concentrationstandardforeachsurface water type

  4. Phosphorus in surface waters • Intercalibrationexercisebetweenmemberstates • Guidance document (notlegally binding) Water Framework Directive Rivers (Claussen et al., 2012) Flanders: 0.14 mg P/l + 0.07-0.14 mg ortho-P/l

  5. Phosphorus in surface waters Lakes (Claussen et al., 2012) Water Framework Directive Flanders: 0.03-0.11 mg P/l

  6. Phosphorus in surface waters • Difficult to compare: • Type of concentration • Statistics • Water type • Time of measurement • Monitoringnetwork Source: van Grinsven et al., 2012 • Thresholds are exceeded in Europe: • 60% of NiDmeasuringpointsin Flanders • 57% of NiDmeasuringpointsin the Netherlands • → P application in agriculture is targeted

  7. Phosphorus in agricultural soils target zone P loss yield Soil P concentration • Phosphoruslossesfromsoil • In general: lossesincreasewithincreasingsoil P concentration • Often: exponentialincreaseabove a threshold P concentration • Important: transport and hydrological factors • → Keep soil P concentrationunderthreshold

  8. Phosphorus in agricultural soils target zone P loss yield Soil P concentration • BUT whataboutcropyields? • Farmers fear smaller cropyields • However: none/smallyieldreductionsexpected at P-input < P-exportgiven the largesoil P reserves in NW Europe

  9. Phosphorus in agricultural soils target zone P loss yield Soil P concentration • Target zone: • optimum cropyields (agro-economical) • Minimal soil P losses (ecological) • Left of target zone: P input > P export • In target zone: P input = P export (equilibriumfertilisation) • Right of target zone: P input < P export

  10. How to reach the target zone? P loss target zone yield Soil P concentration • Target zone of fertilisationadvice • often> economic/ecological target zone • Wide variation in Europe 1. Sound fertilisation advice Source: Jordan-Meille et al., 2012

  11. How to reach the target zone? target zone P loss yield Soil P concentration • Flanders: highest target zone forfertilisationadvice • + fertilisationadvicefor target zone soils > P export 1. Sound fertilisation advice a Average for the target zone according to the Bodemkundige Dienst België (Maes, 2012) b Average in the Netherlands (Ehlert et al., 2009)

  12. How to reach the target zone? • A needforupdatedfertilisationadvice • New knowledge and methods • Adviceoftenbasedon trials from40 yearsago and limitedtestedcrops • Significant effort! • Example: the Netherlands (seepresentation23) • In addition: farmers oftenapply more than the recommendeddose 1. Sound fertilisation advice

  13. How to reach the target zone? • Phosphorusapplicationstandards to limit soil P concentrations • Most countries: no P limits • a First numbers: for 2013-2014. Numbers between brackets: proposed standards from 2017 on. Standard for phosphate saturated soils: 40 kg P2O5/ha/yr; • b Agricultural system: grassland or arable crops; c Standards only for organic P fertilisation 2. Application standards

  14. How to reach the target zone? target zone target zone target zone target zone target zone target zone P loss P loss P loss P loss P loss P loss yield yield yield yield yield yield Soil P concentration Soil P concentration Soil P concentration Soil P concentration Soil P concentration Soil P concentration • Differentiation of the P applicationstandards? • Cropdifferentiation (Flanders, Belgium): P limit ≈ P-export • Soil Pdifferentiation (the Netherlands): P limit according to P soil • Soil P and cropdifferentiation (Ireland) 2. Application standards

  15. How to reach the target zone? • Flanders: nocropdifferentiationwithin the vegetablegroup: • 65 kg P2O5/ha/yr = 28 kg P/ha/yr(2017: 55 kg P2O5/ha/yr = 24 kg P/ha/yr) • Ireland: standards • in kg P/ha/yr 2. Application standards

  16. How to reach the target zone? • Flexibility in applicationstandards? • The Netherlands: 20 kg P2O5/ha/yrtransferrableto nextyear • The Netherlands and Flanders: P applicationby compost accounts foronly 50% • Not present in legislation: higherapplicationstandardswhen more thanonecrop per year is grown 2. Application standards

  17. Remarks • Despiteattemps to reduce P fertilisation, P concentrations in water bodiesremain high • Low mobility of P • Legacy P • Contribution of point sources? • Even if P concentrationdecreases, ecologynotameliorated • Alternatives • Targeting point sources • Targeting transport, edge-of-fieldmeasures (e.g. chemicalsoilamendments, capturing P in wetlandsor filters, etc.)

  18. Conclusion target zone P loss yield Soil P concentration • Largedifferences in Europe • P concentrationstandards in water bodies • Monitoring • P fertilisationadvice • P applicationstandards • Whentargetingagricultural P application: P gift shouldbeadapted to soil P concentration and cropdemand • Sound fertilisationadvice • Differentiatedapplicationstandards

  19. P Thanks for your attention! P P P P Fien Amery Bart Vandecasteele P P P Nutrihort September 17 2013 Institute for Agricultural and Fisheries Research Plant Sciences Unit www.ilvo.vlaanderen.be Agriculture and Fisheries Policy Area

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