Evaluating nutrient source regulations at different scales in five agricultural catchments

Wall, D. P. and Murphy, P. N. C. and Melland, A. R. and Mechan, S. and Shine, O. and Buckley, C. and Mellander, P. -E. and Shortle, G. and Jordan, P. (2012) Evaluating nutrient source regulations at different scales in five agricultural catchments. Environmental Science and Policy, 24. pp. 34-43. ISSN 1462-9011


The European Union (EU) Nitrates Directive constrains nitrogen (N) and phosphorus (P) use and management on agricultural land with the expectation that better nutrient source management will improve water quality. Linking the effects of agricultural practices to impacts on water quality is a challenging task in terms of deciding on appropriate measurement scales. At national scale in Ireland, P fertiliser use and the numbers of soils tested with excessive P levels have declined since the introduction of the Nitrates Directive policies. However, in a detailed study of five benchmark agricultural catchments, between 6 and 26% of the soil still had excessive soil test P levels, showing the legacy effect of over application of P fertilisers and manures in the past. At farm and field scale large spatial variability in soil P fertility levels due to poor manure and fertiliser distribution was evident. The range of soil test P levels on most farms shows scope to correct these imbalances with better nutrient management planning. The application of critical source area management also needs to be considered; significant differences were shown between soil P attenuation and loss for different soil types across these catchments, for which the regulations do not discriminate. The multi-scale approach employed in this study allows a full spatial and temporal realisation of source and an appreciation of the management constraints which underlie nutrient management decisions on farms. A better understanding of nutrient source management in relation to regulatory compliance standards is needed in order to establish whether current policy instruments will bring about reductions in nutrient losses that are expected to result in improved water quality. For this a better farm-scale nutrient auditing tool could be used to improve the spatial distribution of nutrients, accounting for the influence of soil type and landscape hydrology factors on nutrient source mobilisation and loss.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2012 Elsevier Ltd. Permanent restricted access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 18 Aug 2014 02:00
Last Modified: 02 Feb 2017 05:32
Uncontrolled Keywords: catchments; nitrates directive; nitrogen; nutrient management; phosphorus
Fields of Research : 09 Engineering > 0905 Civil Engineering > 090508 Water Quality Engineering
16 Studies in Human Society > 1605 Policy and Administration > 160507 Environment Policy
18 Law and Legal Studies > 1801 Law > 180111 Environmental and Natural Resources Law
Socio-Economic Objective: D Environment > 96 Environment > 9609 Land and Water Management > 960904 Farmland, Arable Cropland and Permanent Cropland Land Management
Identification Number or DOI: 10.1016/j.envsci.2012.06.007
URI: http://eprints.usq.edu.au/id/eprint/25784

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