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| Titel |
Horse paddocks - an emerging source of agricultural water pollution |
| VerfasserIn |
Mohammed Masud Parvage, Barbro Ulén, Holger Kirchmann |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101874
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| Publikation (Nr.) |
 EGU/EGU2015-1137.pdf |
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| Zusammenfassung |
| Horse farms occupy about 4% of the total agricultural land in the EU but are not well
investigated with regard to their impact on water quality. Horse paddocks commonly hold
horses on a limited space and the animal density often exceeds the recommended
density. Therefore, paddock soils receive significant amounts of phosphorus (P) and
nitrogen (N) through feed residues and deposition of faeces and urine, which can
lead to nutrient build-up in the soil and subsequent losses to aquatic systems. This
study characterized the potential risk of phosphorus (P) and nitrogen (N) leaching
losses from Swedish horse paddocks through three stage examination of soil and
water P and N status. The experiment began with a pilot study where surface soil P
status and eight years of drainage P data were examined from a paddock catchment
and an adjacent arable catchment both receiving similar amount of P and N over
years. Results showed that there were no signi?cant differences in water-soluble
P (WSP) or total P data in soils but the drainage water P concentrations, being
higher in the paddock catchment (0.33 mg P l-1, mainly in dissolved reactive form)
than the arable catchment (0.10 mg P l-1). In the second experiment, soil P and N
status were examined in different parts of horse paddocks (feeding, grazing, and
excretion areas) to identify existence of any potential hotspots for losses within the
paddock. In total, seven horse farms, covering different grazing densities and soil
textures representative of Swedish horse paddocks were examined. The results showed
that concentrations of WSP, plant available P or P-AL (P extracted in ammonium
acetate lactate solution at pH 3.75), and total N were highest in feeding and excretion
areas within the paddocks. It was also observed that the WSP concentration in the
paddocks was strongly correlated with horse density (R2 = 0.80, p < 0.001) and
P-AL with years of paddock management (R2 = 0.78, p < 0.001). In the final
experiment, topsoil columns (0-20 cm) from the different segments of the paddock were
isolated and potential leaching losses of P, N and carbon (C) were measured from
two representative horse paddock (a clay and a loamy sand) following simulated
rainfall events in the laboratory. Results showed that the leachate concentrations and
net release of P, N, and dissolved organic C (DOC) from paddock topsoils were
highest in feeding and excretion areas and considerably higher from the loamy
sand than the clay paddock topsoil. It was concluded that: i) horse paddocks pose a
potential threat to water quality via leaching of excess P and N, ii) feeding and
excretion areas are potential hotspots for highly enhanced leaching losses, and iii)
paddocks established on sandy soils are particularly susceptible to high losses. |
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