Forecasting the decline of excess soil phosphorus in agricultural catchments

Wall, D. P. and Jordan, P. and Melland, A. R. and Mellander, P. -E. and Mechan, S. and Shortle, G. (2013) Forecasting the decline of excess soil phosphorus in agricultural catchments. Soil Use and Management, 29 (S1). pp. 147-154. ISSN 0266-0032

Abstract

Measures within the European Union Nitrates Directive National Action Programmes in many member states aim to reduce soil phosphorus (P) levels from excessive to agronomically optimum. This is to reduce the risk of diffuse P losses to water and ultimately help achieve the Water Framework Directive targets of good water quality status. In this study, a 'Soil P Decline' model was used to evaluate this expectation for soils in four intensive agricultural catchments. Realistic annual P-balance scenario deficits (-30, -15, -7 kg P/ha) were used to estimate the average time required for soils to decline to optimum levels in two predominantly arable and two grassland catchments with excessive soil test P (STP). Depending on the STP concentration and total P reserves, for the smallest field P deficit scenario (-7 kg P/ha), the model predictions were for an average of between 5 and 20 yr for agronomically optimum levels to be reached. Under the largest P deficit scenario (-30 kg P/ha), it was forecast to take between 2 and 10 yr. These predictions highlight the likely time lag that exists between implementation of soil P mitigation regulations and the desired outcome of few or no fields with excessive soil P. Expectations for water quality improvement through diffuse P source mitigation must also factor in additional time for P decline model uncertainty, land management variability and time for P sources to transfer to and within river networks.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2013 The Authors and British Society of Soil Science. 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 00:12
Last Modified: 07 Mar 2017 04:36
Uncontrolled Keywords: arable; diffuse P sources; grassland; phosphorus balance; water quality
Fields of Research : 05 Environmental Sciences > 0503 Soil Sciences > 050304 Soil Chemistry (excl. Carbon Sequestration Science)
09 Engineering > 0905 Civil Engineering > 090508 Water Quality Engineering
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070107 Farming Systems Research
Socio-Economic Objective: D Environment > 96 Environment > 9614 Soils > 961402 Farmland, Arable Cropland and Permanent Cropland Soils
Identification Number or DOI: 10.1111/j.1475-2743.2012.00413.x
URI: http://eprints.usq.edu.au/id/eprint/25782

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