HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Chardon, W.J. Articles by Koopmans, G.F. Search for Related Content PubMed PubMed Citation Articles by Chardon, W.J. Articles by Koopmans, G.F. Agricola Articles by Chardon, W.J. Articles by Koopmans, G.F.

Phosphorus Workshop

Phosphorus Workshop

Soil Science Centre, Wageningen University, and Research Centre, Wageningen, the Netherlands

	Introduction

TOP Introduction REFERENCES

 
THE PAPERS in this section were presented at the Fourth International Phosphorus Workshop (IPW4), "Critical Evaluation of Options for Reducing Phosphorus Loss from Agriculture," held in Wageningen, the Netherlands, in August 2004. A primary reason that the workshop was organized is that public concerns over the environmental effects of eutrophication are widespread. The role of phosphorus (P) in eutrophication of surface water has long been recognized. Negative effects of eutrophication include reduced biodiversity of aquatic ecosystems and surface water quality and algal blooms that restrict the use of surface waters for recreation and drinking water production. Algal toxic substances have caused fish kills and animal and human diseases in the past. Reduction of P inputs to surface waters is thus necessary, mostly starting with diminishing industrial losses, precipitating P in sewage water treatment plants, and increasing the number of households that are connected with sewage systems. Because of these reductions, the relative contribution of agriculture to the total P input to aquatic systems has increased to more than 50% in many European watersheds (Kronvang et al., 2005). In the United States, human health effects of the dinoflagellate Pfiesteria piscida have lead to great public concern. Since the outbreak of this organism was ascribed to eutrophication caused by agriculture (Pierzynski et al., 2005), this has lead to a large increase in research efforts on P in the United States. In Europe, the Water Framework Directive will force authorities of watersheds to improve the ecological status of the water in the near future (Kronvang et al., 2005). For many waterways, this implies a reduction of nutrient inputs, particularly P. The need for reducing P loss from agriculture is thus clear, and studies on P source and transport mechanisms are numerous. Research on reducing P losses is also expanding, and many different management practices have been proposed and tested (and sometimes rejected) under different soil, crop, and environmental conditions. Thus, there is a strong need for a critical evaluation of these options, to reduce further research where little benefit is likely and to expand research on options that have proven to be successful.

Since 1995, International Phosphorus Workshops have been held every three years. The first was held in Wexford, Ireland, with papers from this workshop published in Tunney et al. (1997). The second took place in 1998 in Antrim, Northern Ireland, with papers published in Journal of Environmental Quality (first issue of Volume 29, 2000) and introduced by Sharpley et al. (2000). The third was organized in 2001 (Plymouth, UK) with abstracts published in Haygarth et al. (2001). The fifth workshop will be held 3–7 Sept. 2007 in Silkeborg, Denmark, and organized by Brian Kronvang and Goswin Heckrath (see www.ipw5.dmu.dk). Past workshops, and papers published afterward, have greatly contributed to increasing in our knowledge about the relation between agriculture and P losses, the transfer of P from soil to water, and effects on surface water.

The IPW4 was a platform for evaluating the effectiveness, under varying conditions, of different strategies for reducing P losses from fields, and the transport of P in, or effects of P on, the quality of surface waters. Discussions included the influence of best management practices on specific forms of P (inorganic, organic, and particulate), interactions with the nitrogen cycle, and economic aspects. Source-orientated options, like drastic reductions of P inputs to agriculture, or prevention of P transport from agricultural fields, might be considered to be most effective for avoiding unwanted effects. However, when considerable amounts of P have accumulated in the soil from past management, significant reductions in P losses may take considerable time. Edge-of-field options for reducing P transport in surface water and for abating the consequences of eutrophication in surface water were also discussed. The workshop website (www.ipw4.alterra.nl) gives access to the program, abstracts, a list of attendees, workshop report, and a list of mitigation options, a number of which with relevant references.

The six workshop papers published in this issue of Journal of Environmental Quality deal with mitigation options that vary from animal diet modifications to constructed wetlands. Maguire et al. (p. 2093–2103) discuss dietary strategies that lead to less P excretion by animals, but can also lead to an increase in P mobility after manure application. Moore and Edwards (p. 2104–2111) discuss the addition of alum to poultry litter. This leads to less NH₃ volatilization during housing and less P loss in runoff, but also could lead to leaching losses of Al or to toxicity of Al to plants. Dayton and Basta (p. 2112–2117) discuss the effectiveness of using drinking water treatment residuals for reducing the mobility of P in the soil, and the risk of loss via leaching and surface runoff. Cox et al. (p. 2118–2128) investigated the option of reducing P loss via runoff via gypsum addition to soils and the role of subsurface flow in this process. Kronvang et al. (p. 2129–2144) review widely varying options for mitigating P losses from agricultural areas in river basins. Effects, uncertainties, and factors that cause a delay in response during monitoring are summarized. Finally, Braskerud et al. (p. 2145–2155) discuss constructed wetlands that can act as a last buffer in a catchment, preventing P from entering downstream surface water. The influence of various factors on the retention of dissolved and particulate P by wetlands is reviewed. We hope that the workshop articles presented in this issue serve as valuable information sources for those interested in mitigating P losses to the environment.

The workshop led to a number of general conclusions (see IPW4 website for details). It was concluded that the continuing interest in P by policymakers, researchers, and managers is based on the facts that:

• P is an essential element for plant, animal, and human growth, while the native supply by soils is too low to sustain economical optimum crop yields and P contents, especially in developing countries. Since reserves of rock-P needed for the production of P fertilizers are finite, careful management of this resource is needed;
  
• increased soil P levels in heavily manured and fertilized agricultural soils, especially in affluent countries with intensive animal production systems, pose a great risk of P movement to surface waters; and
  
• loading of P is the crucial factor in the eutrophication of fresh water systems; to circumvent large-scale eutrophication and ecosystem deterioration, P discharges to surface waters as a result of human activities have to be drastically reduced.
  

A number of successful options for reducing P losses were identified, most of which are discussed in the papers in this issue:

• reduction of amount of P needed for animal production;
  
• addition of chemical binding materials to manure and soils;
  
• implementation of best management practices, and
  
• constructed wetlands, especially for particle-bound P.
  

It was concluded that risk assessment technologies can significantly contribute to the identification of hot spots and exploration of the optimal set of mitigation options. GIS-based databases and well-tested models are indispensable for this purpose. There is a need for more integrated studies covering the whole cause–effect chain from measures taken in agriculture to the ecological effects in surface waters.

The following specific research needs were formulated:

• more testing of options on an experimental scale under different conditions;
  
• validation of models on these data sets, for extrapolation purposes;
  
• implementation of source and effect oriented measures on a catchment scale;
  
• extrapolation of experiments to larger scales (especially the catchment scale);
  
• integrated approach studies (chain approach, from decision making via management to the effect on aquatic systems);
  
• an evaluation of cost effectiveness of options under different conditions.
  

These research needs are intended to be elaborated in a new COST (European Cooperation in the field of Scientific and Technical Research) Action on the topic "Mitigation options for reducing nutrient emission to surface water and groundwater." This Action is aimed to start in 2006; see the IPW4 website for a link to information about this Action.

As organizers of the symposium, we wish to acknowledge the sponsorship of the Dutch Ministries of Agriculture, Nature and Food Quality; Spatial Planning, Housing and the Environment; and Transport, Public Works and Water Management. We also wish to express our appreciation to the local co-organizers Oene Oenema and Oscar Schoumans (Alterra, Wageningen, the Netherlands); the members of the Scientific Committee, Paul Boers (RIZA, Lelystad, the Netherlands), Phil Haygarth (IGER, North Wyke, UK), Lowie van Liere (RIVM, Bilthoven, the Netherlands), Andrew Sharpley (USDA, University Park, PA, USA), Tom Sims (Univ. of Delaware, Newark, DE, USA), and Barbro Ulén (Swedish Univ. Agric. Sciences, Uppsala, Sweden); and to Gary Pierzynski (Kansas State University, Manhattan, KS, USA) for serving as guest technical editor for these papers.

	REFERENCES

TOP Introduction REFERENCES

 

• Haygarth, P.M., L.M. Condron, P.J. Butler, and J.S. Chisholm (ed.) 2001. Proceedings of the International Phosphorus Transfer Workshop, Plymouth, UK. 28 Aug.–1 Sept. 2001. Inst. of Grassland and Environ. Res. (IGER), North Wyke, Devon, UK.
• Kronvang, B., M.E. Bechmann, H. Behrendt, G.H. Rubæk, and O.F. Schoumans. 2005. Phosphorus losses from agricultural areas in river basins: Effects and uncertainties of targeted mitigation measures. J. Environ. Qual. 34:2129–2144 (this issue).[Abstract/Free Full Text]
• Pierzynski, G.M., J.T. Sims, and G.F. Vance. 2005. Soils and environmental quality. 3rd ed. CRC Press, Boca Raton, FL.
• Sharpley, A.N., B. Foy, and P. Withers. 2000. Practical and innovative measures for the control of agricultural phosphorus losses to water: An overview. J. Environ. Qual. 29:1–9.
• Tunney, H., O.T. Carton, P.C. Brookes, and A.E. Johnston (ed.) 1997. Phosphorus loss from soil to water. CABI Publ., Wallingford, UK.

This Article Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Chardon, W.J. Articles by Koopmans, G.F. Search for Related Content PubMed PubMed Citation Articles by Chardon, W.J. Articles by Koopmans, G.F. Agricola Articles by Chardon, W.J. Articles by Koopmans, G.F.