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Forskningsartikel2020Vetenskapligt granskadÖppen tillgång

Impact of P inputs on source-sink P dynamics of sediment along an agricultural ditch network

Ezzati, G.; Fenton, O.; Healy, M. G.; Christianson, L.; Feyereisen, G. W.; Thornton, S.; Chen, Q.; Fan, B.; Ding, J.; Daly, K.

Sammanfattning

Phosphorus (P) loss from intensive dairy farms is a pressure on water quality in agricultural catchments. At farm scale, P sources can enter in-field drains and open ditches, resulting in transfer along ditch networks and delivery into nearby streams. Open ditches could be a potential location for P mitigation if the right location was identified, depending on P sources entering the ditch and the source-sink dynamics at the sediment-water interface. The objective of this study was to identify the right location along a ditch to mitigate P losses on an intensive dairy farm. High spatial resolution grab samples for water quality, along with sediment and bankside samples, were collected along an open ditch network to characterise the P dynamics within the ditch. Phosphorus inputs to the ditch adversely affected water quality, and a step change in P concentrations (increase in mean dissolved reactive phosphorus (DRP) from 0.054 to 0.228 mg L-1) midway along the section of the ditch sampled, signalled the influence of a point source entering the ditch. Phosphorus inputs altered sediment P sorption properties as P accumulated along the length of the ditch. Accumulation of bankside and sediment labile extractable P, Mehlich 3 P (M3P) (from 13 to 97 mg kg(-1)) resulted in a decrease in P binding energies (k) to < 1 L mg(-1) at downstream points and raised the equilibrium P concentrations (EPC0) from 0.07 to 4.61 mg L-1 along the ditch. The increase in EPC0 was in line with increasing dissolved and total P in water, demonstrating the role of sediment downstream in this ditch as a secondary source of P to water. Implementation of intervention measures are needed to both mitigate P loss and remediate sediment to restore the sink properties. In-ditch measures need to account for a physicochemical lag time before improvements in water quality will be observed.

Nyckelord

Drainage water; Farm pollution; Phosphorus; Soil; Agriculture; Sediment

Publicerad i

Journal of Environmental Management
2020, Volym: 257, artikelnummer: 109988Utgivare: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

    UKÄ forskningsämne

    Miljö- och naturvårdsvetenskap

    Publikationens identifierare

    DOI: https://doi.org/10.1016/j.jenvman.2019.109988

    Permanent länk till denna sida (URI)

    https://res.slu.se/id/publ/113722