A review of the cost-effectiveness and suitability of mitigation strategies to prevent Phosphorus loss from dairy farms in New Zealand and Australia
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Date
2012-05
Type
Journal Article
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Fields of Research
ANZSRC::0703 Crop and Pasture Production, ANZSRC::079902 Fertilisers and Agrochemicals (incl. Application), ANZSRC::079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.), ANZSRC::040608 Surfacewater Hydrology, ANZSRC::0503 Soil Sciences, ANZSRC::31 Biological sciences, ANZSRC::37 Earth sciences, ANZSRC::41 Environmental sciences
Abstract
The loss of phosphorus (P) from land to water is detrimental to
surface water quality in many parts of New Zealand and Australia.
Farming, especially pasture-based dairying, can be a source of P
loss, but preventing it requires a range of fully costed strategies
because little or no subsidies are available and the effectiveness
of mitigation strategies varies with different farm management
systems, topography, stream density, and climate. This paper
reviews the cost-effectiveness of mitigation strategies for New
Zealand and Australian dairy farms, grouping strategies into (i)
management (e.g., decreasing soil test P, fencing streams off from
stock, or applying low-water-soluble P fertilizers), (ii) amendments
(e.g., alum or red mud [Bauxite residue]), and (iii) edge-of-field
mitigations (e.g., natural or constructed wetlands). In general, on farm
management strategies were the most cost-effective way of
mitigating P exports (cost range, $0 to $200 per kg P conserved).
Amendments, added to tile drains or directly to surface soil,
were often constrained by supply or were labor intensive. Of the
amendments examined, red mud was cost effective where cost
was off set by improved soil physical properties. Edge-of-field
strategies, which remove P from runoff (i.e., wetlands) or prevent
runoff (i.e., irrigation runoff recycling systems), were generally the
least cost effective, but their benefits in terms of improved overall
resource efficiency, especially in times of drought, or their effect on
other contaminants like N need to be considered. By presenting
a wide range of fully costed strategies, and understanding their
mechanisms, a farmer or farm advisor is able to choose those that
suit their farm and maintain profitability. Further work should
examine the potential for targeting strategies to areas that lose the
most P in time and space to maximize the cost-effectiveness of
mitigation strategies, quantify the benefits of multiple strategies,
and identify changes to land use that optimize overall dairy
production, but minimize catchment scale, as versus farm scale,
nutrient exports.
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Copyright © 2012 by the American Society of Agronomy, Crop Science Society
of America, and Soil Science Society of America. All rights reserved. No part of
this periodical may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, recording, or any information
storage and retrieval system, without permission in writing from the publisher.