Variable response to phosphorus mitigation measures across the nutrient transfer continuum in a dairy grassland catchment

Murphy, P. N. C. and Mellander, P.-E. and Melland, A. R. and Buckley, C. and Shore, M. and Shortle, G. and Wall, D. P. and Treacy, M. and Shine, O. and Mechan, S. and Jordan, P. (2015) Variable response to phosphorus mitigation measures across the nutrient transfer continuum in a dairy grassland catchment. Agriculture, Ecosystems and Environment, 207. pp. 192-202. ISSN 0167-8809

Abstract

Phosphorus (P) loss from soils to water can be a major pressure on freshwater quality and dairy farming, with higher animal stocking rates, may lead to potentially greater nutrient source pressures. In many countries with intensive agriculture, regulation of P management aims to minimise these losses. This study examined the P transfer continuum, from source to impact, in a dairy-dominated, highly stocked, grassland catchment with free-draining soils over three years. The aim was to measure the effects of P source management and regulation on P transfer across the nutrient transfer continuum and subsequent water quality and agro-economic impacts. Reduced P source pressure was indicated by: (a) lower average farm-gate P balances (2.4 kg ha−1 yr−1), higher P use efficiencies (89%) and lower inorganic fertilizer P use (5.2 kg ha−1 yr−1) relative to previous studies; (b) almost no recorded P application during the winter closed period, when applications were prohibited, to avoid incidental transfers; and (c) decreased proportions of soils with excessive P concentrations (32–24%). Concurrently, production and profitability remained comparable with the top 10% of dairy farmers nationally with milk outputs of 14,585 l ha−1, and gross margins of € 3130 ha−1. Whilst there was some indication of a response in P delivery in surface water with declines in quick flow and interflow pathway P concentrations during the winter closed period for P application, delayed baseflows in the wetter third year resulted in elevated P concentrations for long durations and there were no clear trends of improving stream biological quality. This suggests a variable response to policy measures between P source pressure and delivery/impact where the strength of any observable trend is greater closer to the source end of the nutrient transfer continuum and a time lag occurs at the other end. Policy monitoring and assessment efforts will need to be cognisant of this.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty / Department / School: Current - Institute for Agriculture and the Environment
Date Deposited: 04 Apr 2017 06:53
Last Modified: 06 Apr 2017 01:38
Uncontrolled Keywords: phosphorus loss; nutrient transfer continuum; water quality mitigation measures; nutrient management; agricultural catchment; comparative economics
Fields of Research : 07 Agricultural and Veterinary Sciences > 0799 Other Agricultural and Veterinary Sciences > 079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.)
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070101 Agricultural Land Management
05 Environmental Sciences > 0502 Environmental Science and Management > 050206 Environmental Monitoring
Socio-Economic Objective: D Environment > 96 Environment > 9609 Land and Water Management > 960905 Farmland, Arable Cropland and Permanent Cropland Water Management
B Economic Development > 83 Animal Production and Animal Primary Products > 8303 Livestock Raising > 830302 Dairy Cattle
D Environment > 96 Environment > 9606 Environmental and Natural Resource Evaluation > 960608 Rural Water Evaluation (incl. Water Quality)
Identification Number or DOI: 10.1016/j.agee.2015.04.008
URI: http://eprints.usq.edu.au/id/eprint/30871

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