Abstract
Phosphorus losses from arable land need to be reduced to prevent eutrophication of surrounding waters. Owing to the high spatial variability of P losses, cost-effective countermeasures need to target parts of the catchment that are most susceptible to P losses. Field surveys identified critical source areas for overland flow and erosion amounting to only 0.4–2.6 % of total arable land in four different catchments in southern Sweden. Distributed modelling using high-resolution digital elevation data identified 72–96 % of these observed erosion and overland flow features. The modelling results were also successfully used to predict occurrence of overland flow and rill and gully erosion in a catchment in central Sweden. Such exact high-resolution modelling allows for accurate placement of planned countermeasures. However, current legislative and environmental subsidy programmes need to change their approach from income-loss compensation to rewarding high cost effectiveness of implemented countermeasures.
Highlights
Human activities, including modern agriculture, distort the nitrogen (N) cycle and phosphorus (P) flows and have altered the status of lake and marine ecosystems (Rockstrom et al 2009)
Achieving good ecological status for inland waters according to the EU Water Framework Directive and the ambitious Country Allocated Reduction Targets for the Baltic Sea agreed at the HELCOM Copenhagen Ministerial Meeting (HELCOM 2013) will demand further reductions in P transfer from terrestrial systems in general and from agriculture in particular
It should be noted that the observed traces of erosion and overland flow were event specific, meaning that the local conditions before and during the field surveys influenced the results
Summary
Human activities, including modern agriculture, distort the nitrogen (N) cycle and phosphorus (P) flows and have altered the status of lake and marine ecosystems (Rockstrom et al 2009). While losses of N are generally less scale dependent and more management related, the majority (*80 %) of P losses originate from a small proportion of catchment area (*20 %), a situation known as the 80:20 rule (Sharpley et al 2009). These critical source areas (CSAs) coincide with hydrologically active, interconnected areas where overland and/or shallow subsurface flow mobilize and transfer P from terrestrial to aquatic ecosystems (Pionke et al 2000). These CSAs are spatially variable over the watershed and even within individual fields, so differing management levels are appropriate for different areas of the watershed (Gburek et al 2000)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
